16.1 Anglais_Focus

Transcription

16.1 Anglais_Focus

Volume 16, No. 1, 2006 – $10/10€
Focus
WALTHAM
The worldwide journal for the companion animal veterinarian
Canine and feline obesity
• The epidemiology of canine and feline obesity
• How I approach… Obesity management in dogs and cats
• Techniques to assess body composition
• Clinical risks associated with obesity in companion animals
• Management of Satiety
• Nutritional aspects of obesity
WALTHAM Focus
Editorial Committee
Dr. Denise A. Elliott, BVSc
(Hons), PhD, Dipl ACVIM, Dipl ACVN
Communications, Royal Canin, USA
Dr. Pascale Pibot, DVM
Scientific Publishing Manager
Royal Canin, France
Dr. Pauline Devlin, BSc, PhD,
Veterinary Support Manager
Royal Canin, UK
Dr. Karyl Hurley, BSc, DVM,
Dipl ACVIM, Dipl ECVIM-CA
Global Academic Affairs,
WALTHAM
Visiting Faculty Cornell University
Editor
Dr. Richard Harvey, PhD, BVSc,
DVD, FIBiol, MRCVS
Focus
WALTHAM
© Photo: Catherine Wells, WALTHAM Centre for Pet Nutrition, 2006
Vol 16 N° 1 – 2006
WALTHAM Focus is published in English,
French, German, Chinese, Dutch, Italian,
Polish, Portuguese, Spanish, Japanese,
Greek and Russian.
Canine adipocytes
Contents
The epidemiology of canine and feline obesity.......................................................... 2
Marianne Diez & Patrick Nguyen
How I approach… Obesity management in dogs and cats.......................................... 9
Linda Fleeman, E. Judy Seton & Jacquie Rand
Editorial Secretary
Techniques to assess body composition in dogs and cats ....................................... 16
Laurent Cathalan
[email protected]
Denise A. Elliott
Clinical risks associated with obesity in companion animals ................................... 21
Artwork
Alex German
Arnaud Pouzet
Editorial control other languages
Dr. Imke Engelke, DVM (German)
Dr. María Elena Fernández, DVM (Spanish)
Dr. Eva Ramalho, DVM (Portuguese)
Dr. Flavio Morchi, DVM (Italian)
Dr. Margriet Bos, DVM (Dutch)
Prof. Dr. R. Moraillon, DVM (French)
Ecole Nationale Vétérinaire d’Alfort, France
Deputy Publisher: Buena Media Plus
CEO: Bernardo Gallitelli
Address: 85, avenue Pierre-Grenier
92100 Boulogne – France
Phone: +33 (0) 1 72 44 62 00
Printed in the European Union
ISSN 1354-0157
Circulation: 80.000 copies
LEGAL DEPOSIT: March 2006
Published by Aniwa S. A. S.
The licensing arrangements for therapeutic
agents intended for use in small animal
species vary greatly worldwide. In the
absence of a specific licence, consideration
should be given to issuing an appropriate
cautionary warning prior to administration
of any such drug.
Management of Satiety ............................................................................................ 27
Robert C. Backus
Nutritional aspects of obesity .................................................................................. 33
Patrick Nguyen & Marianne Diez
The Royal Canin cut-out and keep guide
Body condition scoring in cats and dogs ................................................................. 39
WSAVA News ............................................................................................................ 41
argentina australia austria bahrain belgium brazil canada china croatia cyprus czech republic denmark emirates estonia finland france
germany greece hong kong hungary iceland ireland israel italy japan korea latvia lithuania malta mexico the netherlands new zealand
norway philippines poland portugal puerto rico romania russia singapore slovak republic slovenia republic of south africa spain
sweden switzerland taiwan thailand turkey united kingdom united states of america
KNOWLEDGE AND RESPECT
WALTHAM® THE WORLD ’ S LEADING AUTHORITY ON PET CARE AND NUTRITION
The epidemiology of canine
and feline obesity
Dr Marianne DIEZ, PhD, Dipl. ECVCN, Master of Conferences of Animal Nutrition
Department of Animal Productions, Faculty of Veterinary Medicine, University of Liège, Belgium
Marianne Diez graduated from the University of Liège in 1989. She joined the Animal Nutrition Unit in 1991, after a
short period in small animal practice. She was awarded a PhD in 1998 and became a founding Diplomate of the ECVCN
(European College of Veterinary and Comparative Nutrition) in 2000. Since 1998, she has been developing a practice in
clinical nutrition at the Faculty of Veterinary Medicine of Liège. She has been a lecturer in general animal nutrition and
clinical nutrition since 2000. Her research interests include dietary fibers, prebiotics and obesity in companion animals.
Patrick Nguyen, DVM, MS, RDH, Dipl. ECVCN
ENVN Atlanpôle - La Chantrerie ; BP 40706 44307 Nantes cedex 03, France
Patrick Nguyen graduated from the Veterinary School of Alfort (France) in 1977. He was Assistant Professor at the Nutrition department
for 2 years before moving on to the newly founded Veterinary school of Nantes. In 1982, he gained the “aggrégation” in
Nutrition and became Professor. He also received a Research Habilitation from the University of Nantes and became a
Diplomate of the European College of Veterinary and Comparative Nutrition. Since 1996, he has been head of the
Nutrition and Alimentation unit and head of the Biology and Pharmacology Department since 2001. His research
interests include obesity and insulin resistance in companion animals (in collaboration with the Human Nutrition
Research Center of Nantes). He is also involved in applied research projects like those on consequences of neutering in
cats and on digestive sensitivity in large breed dogs. Patrick has published more than 100 papers and research abstracts.
He has been President of the European College of Veterinary and Comparative Nutrition since 2004.
KEY POINTS
Á The frequency of canine and feline obesity is at least
20 % in industrialized countries
Á The number of risk factors is high in both species,
with age being particularly important
Á In the dog, breed, gender and inactivity are major risk
factors
Á In the cat, obesity is related with inactivity and
neutering in both genders
Á Excess food intake is always observed in both
species. This is mainly due to an anthropomorphic
behavior of the owner
Á Many diseases are associated with obesity in both
species
Introduction
The treatment of obesity in small animals is a major
challenge for the veterinary profession. The efficacy
of prevention and treatment of obesity relies on a
sound knowledge of the risk factors and a thorough
understanding of the pathophysiology associated
with the condition.
2
WALTHAM Focus
Vol 16 No 1
l
2006
This paper will review the epidemiology of obesity
in the dog and cat. Several epidemiological factors
are common to both species, whilst others differ
and these will be discussed separately.
Incidence rate
The incidence rate of obesity in dogs presented for
consultation varies from 24 to 44% depending on
the author, the site of the epidemiological study,
and the definition of initial criteria (Table 1). All of
the studies that have been performed in veterinary
clinics in industrialized countries give a prevalence
of obesity in dogs of at least 20%. The
epidemiological data does not indicate whether the
frequency of obesity has increased over the last 10
years, however obesity is a major medical problem
in the canine population.
In the cat, the incidence rate of obesity, which was
very low in the 1970's, now exceeds 20%, regardless
of the site of the epidemiological study.
Risk factors
Table 2 summarizes the various risk factors for
The epidemiology of canine and feline obesity
Table 1.
Incidence rate of obesity in canine and feline populations
References
Country
Dog data
Sample size
Mason (15)
Anderson (7)
Edney (16)
Meyer, et al (1)
Steininger (17)
Edney and Smith (3)
Scarlett, et al (18)
Armstrong and Lund (5)
Lund, et al (19)
Robertson(20)
Jerico and Scheffer (21)
Robertson (2)
UK
UK
UK
Germany
Austria
UK
USA
USA
USA
Australia
Brazil
Australia
28%
34%
30%
44%
24%
25%
28%
17%
25%
1000
1134
266
8268
23000
30517
648
860
Cat data
Sample size
9 (6-12)%
429
25%
24%
2000
10000
19%
644
Table 2. Summary of main risk factors
DOG
RISK FACTORS
CAT
Labrador Retriever, Cairn Terrier, Scottish Terrier,
Basset Hound, Cavalier King Charles Spaniel,
Cocker Spaniel, Longhaired Dachshund, Beagle,
and longhaired giant breeds
BREED
and other genetic factors
Domestic short hair
Constant increase in incidence up to 12 years,
followed by a decline
AGE
Maximal risk in middle aged animals,
decreasing after 10 to 12 years of age
More common in females (60%), especially neutered
GENDER AND NEUTERING
More common in males, especially neutered
Significant factor
SEDENTARY LIFESTYLE
Major risk factor in the cat
Diabetes, hypothyroidism, hyperadrenocorticism
ENDOCRINE DISEASES
Uncommon
Relationships observed
DRUGS AND CONTRACEPTIVE TREATMENT
Progestens
Miscalculation of requirements, hence excessive
intake (ad lib feeding, inadequate control,
various supplements)
FEEDING
Miscalculation of requirements, hence
excessive intake (ad lib feeding,
inadequate control, various
supplements)
Excessive anthropomorphism
SOCIOLOGICAL FACTORS
Feeding = means of communication with
the animal
Risk greater if only one animal in household
NUMBER OF ANIMALS
Risk increased if 1 or 2 cats in the
household.
obesity and compares them between dogs and cats.
Some risk factors are associated with energy intake,
others with energy expenditure, whilst several factors act
on both intake and expenditure.
Energy supply comes from ingested, digested and
metabolized food. In mammals, expenditure can be
classified into three categories: basal metabolism in
mammals, postprandial thermogenesis and physical
activity, representing 60, 10 and 30% of energy
expenditure respectively. The contribution of each of
these components varies significantly, according to the
frequency and intensity of physical activity, which is the
key variable in the expenditure side of the energy
equation. However, basal metabolism would appear to
be a stable independent factor, which is primarily
determined by the proportion of lean body mass
(accounting for 90-95% of basal metabolic energy
expenditure compared to 5 to 10% for the fat mass)
(Figure 1). In the dog, basal metabolism represents
between 55 and 70% of the total expenditure.
Breed
The breed of the animal is a risk factor for obesity in
2006
l
Vol 16 No 1
WALTHAM Focus
3
Postprandial
thermogenesis
Physical activity
BMR – lean mass
BMR – fat mass
Figure 3.
These 2 castrated male Poodles
aged 6 and 8 years weighed 12
and 6 kg respectively. They were
adopted as puppies from a refuge
for abandoned animals. They live
under the same conditions. The
obese Poodle is particularly greedy
(Photo. Dr. E. Lhoest, FMV, ULg,
2005).
Figure 1.
The three components of energy expenditure.
Figure 2.
These two obese intact male
rough Collies are owned by
the same person and live
under the same conditions.
They are overfed and were
presented for consultation in
the orthopedic department
(Photo. Dr. E. Lhoest, ULg
2005).
dogs, but authors differ on the relative incidence of
predisposed breeds. Some breeds have been acknowledged
for decades, whilst others seem to be emerging, most
notably the longhaired giant breeds. The pressures on
breeding (changing show standard, popularity of the
breed, change of use {e.g. working breed to pet breed},)
and type of selection may influence the body condition
(and weight) of dogs, for example by substituting beauty
or conformational criteria over working aptitude
(Figure 2). Breed predispositions to obesity are partly
linked to genetic factors and more specifically to the
lean/fat mass ratio.
Conversely, some breeds appear to be somewhat resistant
to obesity: these include Greyhounds and the various
sheep herding breeds. Note, however, that in a study
carried out in Germany, German Shepherd Dogs,
Poodles (Figure 3) and Boxers were often obese (1).
This demonstrates the importance of local factors
affecting perceptions of breed predisposition to obesity.
Not all the dog breeds are equal in terms of nutritional
risk during growth. Excess energy intake predisposes
small breed dogs to excess weight gain whilst in large
breeds, the major risk of excess energy intake is
osteoarticular disorders. The combination of articular
problems and excess weight is however common at the
end of the growth period in large dogs.
In the cat, there is no reported breed predisposition to
obesity. Indeed, one breed, the Abyssinian, does not
appear to be affected. The majority of obese cats are cats
of the so-called "domestic" breeds (crossbreeds, domestic
shorthairs).
4
WALTHAM Focus
Vol 16 No 1
l
2006
Other genetic factors
Mammals have a complex system of genetically
determined factors that are designed to maintain the
equilibrium between food intake and energy
expenditure. Whatever the reason, some individuals
become obese whilst others, living under the same
conditions, maintain their ideal body weight.
The genetic alterations that lead to obesity in the dog are
not yet fully understood, although there is no doubt
about the polygenic nature of obesity. However, it is
undeniable that genetic factors have an active role:
obesity is particularly common in certain breeds of dogs
as well as in certain lines.
Age
The incidence rate of obesity increases with the age of
both the dog (2) and owner (3). Thus, some 6% of
bitches aged 9 to 12 months are obese, whereas some
40% of adult female dogs are obese (4). The mean age at
the time of diagnosis varies from 5 to 8 years. Fewer
than 20% of dogs aged 4 years and under are obese,
compared to more than 50% of dogs in the 7 to 8 yearold category, and nearly 70% of those aged over 9 years
of age. However, recent data shows that the frequency of
obesity decreases in animals aged over 12 years (5).
During aging, both lean/fat mass ratio and basal
metabolism have a tendency to decrease (6).
It should be noted that excess weight in puppyhood
predisposes to obesity in the adult. Obese bitches
between 9 and 12 months of age have 1.5 times more
chances of becoming obese in adulthood than bitches
that are lean during the growth period (4).
In the cat, the risk is greatest between the ages of 5 and 10
years; it then strongly decreases over the age of 10 years.
Gender and neutering
Dogs
Females represent at least 60% of obese dogs. In
addition, a study by Glickman, et al. (4) involving 289
adult bitches reported a 40% incidence of obesity.
Gonadectomy increases the incidence rate of obesity in
the male and especially the female (3). Edney and Smith
(3) have reported that neutered bitches are twice as likely
to become obese as intact females. A recent study
demonstrated that this also applies to males. According
to Robertson (7), the frequency of obesity is 32% in
neutered animals, compared to 15% in entire dogs, both
male and female. The sex hormones are not primary
regulators of metabolism; however, they influence food
intake and body weight both directly, by acting on the
central nervous system, and indirectly by altering cell
metabolism. The estrogens exert an inhibitory effect on
food intake. Food intake therefore varies throughout the
cycle in the female. It is minimal around the time of
estrus, increases during metestrus and is maximal during
anestrus (8).
The effect of early neutering on the incidence of obesity
is unknown. A recent epidemiological study demonstrated that the incidence rate of obesity was lower in a
population of dogs neutered before 5.5 months of age
than in animals neutered between 5.5 and 12 months.
The authors also report an overall incidence of obesity of
27% in the population of neutered dogs (9).
The increase in the practice of neutering in the canine
population may explain the increase in obesity since the
first epidemiological studies were performed in 1960.
Furthermore, as this practice is becoming more and
more widespread, a further increase in incidence is to be
expected over the next few years, including in countries
that up to now have been relatively free of the problem.
Although it is difficult to clarify the link between
neutering and obesity, due to the multi-factorial nature
of the latter, several explanations may be proposed:
• The first point to be considered is the variation in food
intake over the cycle as reported above, and the
inhibitory effect of estrogens on food intake. It is
therefore logical to think that this inhibition is no
longer effective in neutered bitches. During the first
three months after neutering, 4 female Beagles
consumed 20% more food than entire control animals,
and their body weight subsequently increased
significantly (8).
• Another study has investigated this problem, by
measuring not the increase in weight in neutered
females but the actual quantities of energy required to
maintain a body weight - considered as being ideal - in
Beagle bitches. A 30 % decrease in daily energy intake
in comparison with the ration provided prior to
neutering was found to be necessary in the weeks
following ovariohysterectomy to maintain the bitches
at their ideal weight (10).
• Neutering also causes a decrease in spontaneous
activity, especially in males. This last point is difficult
to quantify under experimental conditions.
Weight gain following neutering could therefore be
prevented by strict rationing and regular exercise. In a
study with working dogs (German Shepherds) subjected
to regular exercise and receiving the same amount of
food, no difference in body weight was demonstrated
between neutered and entire dogs. This data tends to
prove that maintaining regular exercise after sterilization
can prevent weight gain (11).
Cats
Castrated cats are 3 to 4 times more likely to be obese
than entire individuals, and males are more often
affected than females, who have a higher resting
metabolic rate. The increased body weight of neutered
cats has been proven experimentally; however, these
trials did not elucidate the exact cause of the problem.
One can however confirm the hypothesis that the
removal of estrogens plays a major role in metabolic
regulation. Recent studies have demonstrated that they
inhibit lipogenesis and are determining factors for the
number of adipocytes, even in males (12).
It has been clearly established that onset increased
energy intake in male cats was rapid - from the 1st week
after the neutering - and significant: to the order of 15%
(week 1 after neutering) to 80% (week 7). This
increased food intake after several weeks induced an
increase of around 30% in body weight, mainly in the
form of fat. Hormones such as insulin and leptin,
increased, but did not play their role of appetite regulation.
Energy expenditure also seems to be reduced following
neutering. However, since the activity and behavior of
animals kept indoors are little changed, the decreased
energy expenditure is related to a decrease in the basal
metabolic rate. The exact mechanisms are still not fully
understood.
Finally, it should be emphasized that the age of the cat at
the time of neutering has no effect on the development
of obesity.
2006
l
Vol 16 No 1
WALTHAM Focus
5
Contraceptive treatments
During a clinical trial, contraceptive treatment using
medroxyprogesterone acetate led to a significant weight
gain in 17.4% of treated bitches. The authors reported
bulimia and obesity in some animals (13).
Obesity and endocrine disorders
In the dog, obesity may be associated with certain
endocrine disorders such as diabetes and
hypothyroidism. At least 40% of dogs that suffer from
one of these diseases are obese.
Obesity may also be secondary to hyperadrenocorticism
(Figure 4). In a clinical study, 5 out of 8 dogs presented
with fat deposits typical of obesity and different from a
pendulous abdomen.
Obesity secondary to medication
Some drugs may lead to hyperphagia and secondarily
excess body weight; the primary culprits are the
antiepileptics and glucocorticoids.
Sedentary lifestyle and lack of exercise
Dogs
In the dog, a lack of exercise is a fundamental factor in
the development of obesity: the prevalence of obesity
decreases in proportion with the duration of weekly
exercise. It is however impossible to determine whether
the obesity is responsible for exercise restriction or
whether it is the lack of exercise that contributes to the
development of obesity. The duration of weekly exercise
is a more precise criterion than the type of habitat for
evaluating energy expenditure. Dogs living in flats or in
a house are generally more obese than dogs living
outdoors (31% versus 23%) (2). Nevertheless, it is
Figure 4.
The Auvergne Pointer in this
photo is particularly obese
(Body condition score of 9/9).
He has Cushing's disease; his
mobility is drastically reduced.
(Photo. Dr M. Diez, FMV,
ULg 2005)
Figure 5.
Morbidly obese cat: This adult
cat is a sedentary castrated male
aged 6 years. He weighs 11 kg
(Photo. Dr. E. Lhoest, FMV,
ULg 2005)
6
WALTHAM Focus
Vol 16 No 1
l
2006
erroneous to believe that the availability of a large garden
systematically increases energy expenditure. Some
animals living in a confined environment are taken out
for walks several hours per week, whilst others, with a
garden available, are content to make use of it for only a
few minutes each day.
Cats
The cat is a predator whose feeding behavior in the wild
is linked to hunting. Predatory activity therefore takes
up two thirds of its time. Moreover, in the wild, only
one out of every 15 hunting expeditions is successful.
The cat is therefore used to short periods of intense
activity leading to energy expenditure. It should be
remembered that eating is not a social activity in the cat,
which is a solitary animal. Hunting and eating are
motivated by factors that are independent of one
another. Playing and grooming are also activities that
consume energy, and which may be modified in indoor
cats.
Our domestic cats have little in common with their wild
relatives:
• They live an extremely sedentary lifestyle, are neutered
and often overfed
• Their owners are often ignorant of their behavioral
needs: living in a restricted space with a lack of daily
exercise, both in terms of duration and intensity
• Sedentary cats generally sleep longer than nondomestic cats (12 to 18 hours versus a maximum of 12
hours), which may greatly influence energy
expenditure and as a result body weight control
(Figure 5)
The type of food and miscalculation of energy
requirements
The following nutritional causes have been clearly
identified and are common to both dogs and cats:
• Food intake that does not take into account energy
requirements
• Ad lib feeding, "my animal eats everything that I give it"
• Supplements in the form of titbits or fatty acid
supplements that are not accounted for in the total
energy supply
• The provision of very appetizing food, rich in fats and
soluble sugars
An undeniable risk factor is ad libitum, feeding leading
to excessive energy intake. Ad lib feeding is not
advisable as the majority of dogs and cats are unable to
regulate their food intake, particularly when the energy
concentration (and therefore the fat content) of their
diet is high. The fattest foods are often the most highly
concentrated in energy, often the most flavorsome and
fats are very well digested and stored by domestic
carnivores. Offering titbits, leftovers of the owner's meal
and various nutritional supplements are additional risk
factors (2).
There is controversy over the influence of restricted
rations on the development of canine obesity. The
underlying idea is that dogs who receive restricted
rations will be more often "rewarded" with titbits and
end up receiving larger amounts of food. This view can
only be supported in countries where dogs are still fed in
a "traditional" way, with restricted rations or table
scraps. In North America, 95% of animals receive
commercial feeds and yet canine obesity does not seem
to be any less prevalent than in some European
countries. In fact it is quite the opposite.
A recent epidemiological study demonstrated that the
type of food (wet versus dry) did not have any significant
effect on the incidence rate of canine obesity (2). Unlike
some widely held views, offering an adapted daily ration
in several smaller meals does not lead to an increase in
the frequency of obesity. In most epidemiological
studies, the obese dogs are fed once daily (2, 14).
Naturally, one should not confuse the division of an
appropriate daily ration with the multiplication of
various treats that are added to it.
The social dimension of food
The possession of several animals may pose the problem
of controlling individual consumption. However, obesity
is more common in households that have only one dog
(2, 14)
any demand from the animal as a demand for food.
These owners clearly do not worry about providing a
balanced diet. Some of these aspects are well known to
practitioners, but this study had the merit of making it
more objective by using a questionnaire (14).
The data presented above may appear to be fairly
discouraging at first glance, and they do not enable a
clear differentiation to be made between simple
correlations (for example, between the weight of the
owner and the weight of the dog) and the causes of
obesity. They are however very useful for the
development of preventive and corrective programs for
canine obesity. They draw attention to environmental
factors, in the broad sense of the term, which are
theoretically exterior to the animal itself, but of
fundamental importance for its health.
Associated pathology
Up until the end of the 1980's, there were relatively few
data available on obesity-linked diseases in the dog and
cat. Also, some authors extrapolated data from
epidemiological studies performed in man. However,
the simple transposition of human data (diabetes,
hypertension, etc.) to the obese dog or cat does not
provide all the answers. Clinical data, which is being
published more and more often, needs to be carefully
studied (See Alex German’s paper on page 21).
It should be noted that several reported disorders are
reversible. Thus, exercise intolerance (Figure 6),
inactivity, and musculoskeletal or respiratory disorders
are generally reduced or may totally disappear.
Reversible metabolic disorders include disorders such as
insulin-resistance and dyslipidemias.
In the cat, the risk of obesity is greater in animals that
live alone or with one other cat, in comparison with
households with 3 or more cats.
The role of feeding in the relationship between man and
his domestic pet plays a major role in the development
of obesity. As shown by a recent study (14), this
relationship is characterized by an excessive anthropomorphic behavior, or even anthropocentrism. For
example, the owners of obese dogs talk to their dogs
more, allow their animal to sleep with them, do not fear
zoonotic diseases, and consider that exercising, working,
or guarding the house are not important for the dog. It
is of no surprise therefore to note that obese animals
receive meals or treats more often than animals of a
normal weight. The owners of obese animals interpret
Figure 6.
Male castrated English Bulldog, presented for a clinical nutrition consultation at
the request of the surgeons. This dog must lose weight prior to undergoing surgery.
He weighs 33kg and is suffering from brachycephalic syndrome and exercise
intolerance (Photo. Dr. E. Lhoest, FMV, ULg 2005).
2006
l
Vol 16 No 1
WALTHAM Focus
7
Conclusions
A sound knowledge of risk factors and associated
pathologies is vital for the instigation of means for the
effective disease prevention. It would appear that the
major factors in the dog and cat include gonadectomy, a
sedentary lifestyle, and the ignorance of the nutritional
requirements and behaviors of these two species. u
References
1. Meyer H, Drochner W, Weidenhaupt C. Ein Beitrag zum Vorkommen und
zur Behandlung der Adipositas des Hundes. Deutsche Tierärztliche
Wochenschrift 1978; 85: 133-6.
2. Robertson ID. The association of exercise, diet and other factors with
owner-perceived obesity in privately owned dogs from metropolitan Perth,
WA. Prev Vet Med 2003; 58: 75-83.
3. Edney ATB, Smith PM. Study of obesity in dogs visiting veterinary
practices in the United Kingdom. Vet Rec 1986; 118: 391-6.
4. Glickman LT, Sonnenschein EG, Glickman NW, et al. Pattern of diet and
obesity in female adult pet dogs. Vet Clin Nutr 1995; 2: 6-13.
5. Armstrong PJ, Lund EM. Changes in body condition and energy balance
with aging. Vet Clin Nutr 1996; 3: 83-87.
6. Speakman JR, van Acker A, Harper EJ. Age-related changes in the
metabolism and body composition of three dog breeds and their relationship
to life expectancy. Aging Cell 2003; 2: 265-75.
7. Anderson RS. Obesity in the dog and cat. Vet Ann 1973; 14: 182-6.
8. Houpt KA, Coren B, Hintz HF, et al. Effect of sex and reproductive status
on sucrose preference, food intake, and body weight of dogs. J Am Vet Med
Assoc 1979; 174:1083-5.
9. Spain CV, Scarlett JM, Houpt KA. Long-term risks and benefits of earlyage gonadectomy in dogs. J Am Vet Med Assoc 2004; 224: 380-7.
10. Jeusette I, Detilleux J, Cuvelier C, Istasse L, Diez M. Ad libitum feeding
following ovariectomy in female Beagle dogs: effect on maintenance energy
requirement and on blood metabolites. J Anim Phys Anim Nutr 2004; 88(3-4):
117-121.
8
WALTHAM Focus
Vol 16 No 1
l
2006
11. Le Roux PH. Thyroid status, oestradiol level, work performance and
body mass of ovariectomised bitches and bitches bearing ovarian
autotransplants in the stomach wall. J South Afr Vet Assoc 1983; 54: 115-7.
12. Cooke PS, Naaz A. Role of oestrogens in adipocyte development and
function. Exp Biol Med 2004; 229: 1127-35.
13. Picavet S, Le Bobinnec G. Utilisation de la proligestérone chez la chienne :
à propos de 160 cas. Prat Med Chir Anim Comp 1994; 29: 313-320.
14. Kienzle E, Bergler R, Mandernach A. Comparison of the feeding behavior
and the man-animal relationship in owners of normal and obese dogs. J Nutr
1998; 128: 2779S-2782S.
15. Mason E. Obesity in pet dogs. Vet Rec 1970; 86: 612-6.
16. Edney ATB. Management of obesity in the dog. Vet Med Small Anim
Pract 1974; 69: 46-9.
17. Steininger RE. Die Adipositas und ihre diatetische Behandlung. Wien
Tierarztl Mschr 1981; 68: 122-30.
18. Scarlett JM, Donoghue S, Saidla S, et al. Overweight cats: prevalence and
risk factors. Intern J Obes 1994; 18: S22-S28.
19. Lund EM, Armstrong PJ, Kirk CA, et al. Health status and population
characteristics of dogs and cats examined at private veterinary practices in the
United States. J Am Vet Med Assoc 1999; 214: 1336-41.
20. Robertson ID. The influence of diet and other factors on owner-perceived
obesity in privately owned cats from metropolitan Perth, Western Australia.
Prev Vet Med 1999; 40: 75-85.
21. Jerico MM, Scheffer KC. Epidemiological aspects of obese dogs in the city
of Sao Paulo. Clinica Veterinaria 2002; 37: 25-9.
How I approach...
Obesity management in dogs
and cats
Linda M. Fleeman, BVSc, MACVSc
Centre for Companion Animal Health, School of Veterinary Science, The University of Queensland, St Lucia,
QLD 4072 Australia
Linda Fleeman holds a faculty position in the School of Veterinary Science at the University of Queensland in Australia
and has a strong clinical research background in canine diabetes mellitus. She completed Clinical Residency training
in Small Animal Medicine at Murdoch University and the University of Melbourne in Australia and worked as a
referral small animal medicine clinician before embarking on a PhD research project investigating the clinical
management of canine diabetes mellitus. Linda Fleeman has lectured at international meetings and is the author of numerous papers
on canine diabetes.
E. Judy Seton, BVSc, DipVetClinStud, PhD
School of Veterinary Science, The University of Queensland St Lucia, QLD 4072 Australia
Judy Seton graduated from the University of Queensland in 1980. She subsequently undertook a Diploma of
Veterinary Clinical Studies at Sydney University. She obtained her Ph.D. from the University of Queensland in 1994.
From 1994 to 2004, she has been actively involved in clinical medicine and practice management in four private
practices in Brisbane. She has been lecturing in small animals at the University of Queensland for the past 18 months.
Her interest areas are small animal cardiology, internal medicine and clinical nutrition.
Jacquie Rand, BVSc, DVSc, DACVIM
Professor of Companion Animal Health, Centre for Companion Animal Health, School of Veterinary Science,
The University of Queensland St Lucia, QLD 4072 Australia
Professor Rand graduated from Melbourne University (Australia) in 1975 and worked in private practice for 8 years
before completing a residency and doctorate at the University of Guelph (Canada). She is currently Professor of
Companion Animal Health at the University of Queensland. Jacquie Rand is recognized internationally as a leader in
feline diabetes and nutrition research, authoring many journal articles, abstracts and book chapters. She currently has
a team of postgraduate students working in diabetes, obesity and nutrition research in companion animals. Jacquie
Rand is also Director of the Centre for Companion Animal Health, which is committed to improving the health and welfare of companion
animals and increasing the contribution they make to our lives.
Introduction
The concept underlying obesity management is simple;
weight loss occurs whenever daily energy expenditure
exceeds daily consumption of calories. Yet it can be very
challenging to implement successful weight loss
programs for pet dogs and cats. The process of tailoring
obesity management guidelines for individual cases is
illustrated here using clinical examples. The key is to use
detailed evaluation of diet history and lifestyle to first
identify all the specific owner and animal constraints
that will affect implementation of a weight loss program,
and then to develop practical solutions that work within
these constraints. The aim is to make it as easy as
possible for owners to comply with their pet’s obesity
management regimen. It is important to consider the
individual companion animal-human bond and to
provide ongoing support and guidance so that
owner motivation and compliance are optimized.
In short, overweight dogs and cats just need to eat less
and run around more. Despite the simplicity of this
concept, it is very difficult to implement obesity
management for pet dogs and cats. Owners
frequently find it challenging to maintain compliance
and motivation for weight loss programs, even when
they believe that their pet’s health will be improved
by reduction of excess body fat.
Specific owner and animal constraints can be
identified for almost every case of pet obesity. It is
these constraints that make the cases so complex
2006
l
Vol 16 No 1
WALTHAM Focus
9
How I approach… Obesity management in dogs and cats
and result in the management regimens being so
difficult for owners to comply with. Success is
dependent firstly on recognition of the constraints for
each individual case, and secondly on development of
effective solutions that work within these constraints.
The following examples illustrate the process of case
evaluation and management for obesity problems in
dogs and cats. The primary goal is always to reduce the
animal’s daily consumption of calories and/or increase
its daily energy expenditure. Emphasis is placed on
detailed evaluation of diet history and lifestyle, and on
identification of all the specific owner and animal
constraints that will affect implementation of an obesity
management program. Recommendations are then
tailored for each individual case with the aim to make it
as easy as possible for the owners to comply with all of
the guidelines.
Lifestyle:
Jodie is reported to have a low to moderate activity level.
Her regular exercise regimen is a 30-minute walk every
morning, and she also occasionally enjoys chasing balls.
Recently, her mobility has markedly decreased but she is
still managing two 10-minute walks each day.
Physical assessment:
• Body weight = 44.7 kg
• Body condition score = 8.5 on a scale of 1 to 9 (4.7 on
a scale of 1 to 5)
Specific owner and dog constraints identified for this case:
Jodie’s owners do not understand why she is so
overweight. They are highly motivated to implement
obesity management because they believe that the excess
body fat is having a negative impact on her health. They
are concerned that she always appears to be hungry and
cannot imagine how she could manage if fed less food.
They do not recall the feeding guidelines that were
recommended when the hydrolyzate diet was first
prescribed, and have never fed the food exclusively for an
elimination food trial. Recently, respiratory difficulty
has limited Jodie’s ability to exercise and she now appears
exhausted after 10 minutes of slow walking.
Diet history:
Food: Jodie’s staple diet is a nutritionally complete and
balanced, prescription dry food formulated with protein
hydrolyzate for dogs with food hypersensitivity
(Metabolizable Energy (ME): 3.72 kcal/g). This diet has
been fed for over 2 years and was prescribed when
recurrent allergic otitis externa was diagnosed. Careful
questioning reveals that a wide variety of additional foods
are fed each day.
Feeding method: Two cups of the prescription dry food is
fed once daily in the evening. This food is prepared by
Specific health issues identified for this case:
Exercise intolerance with respiratory signs in this case is
related to morbid obesity and weight loss is imperative to
manage the problem. It is also suspected that concurrent
osteoarthritis might be contributing to the dog’s decreased
mobility. Chronic, allergic, otitis externa is also a problem
and a short course of oral prednisolone has recently been
prescribed. Jodie has almost completed the course of
tablets and her ear canals are now much improved.
However, exercise tolerance has decreased markedly since
beginning the corticosteroids.
Figure 1.
Case 1, Jodie, weighing
in at 44.7 kg, Body
Condition Score (BCS):
8.5/9 (4.7/5).
Plan for obesity management:
Food: The prescription, protein hydrolyzate, dry food is to
be continued, and to be fed exclusively.
Feeding method: As the owners are willing to implement
strict nutritional guidelines for obesity management, it is
decided to also perform an elimination food trial for eight
weeks to evaluate the role played by food allergy in the
chronic, allergic otitis externa (2). It is recommended to
begin by feeding 2 cups of food twice each day, and to
Case 1: Jodie
Management strategy: education of the owner
regarding their pet’s nutritional needs
Signalment:
• 8 year old, neutered female, Labrador Retriever (Figure 1)
10
one of the owners who presented the animal, and grated
cheese is added to improve palatability. Table scraps are
frequently fed after the owner’s meal and are followed by
ice cream for dessert. A slice of toasted bread with butter
is given each morning, and occasionally bacon and eggs
are also fed at this time. The presenting owner and two
other family members feed a number of other foods
sporadically during the day. All food is always consumed
immediately.
WALTHAM Focus
Vol 16 No 1
l
2006
measure this precisely with a standard 250 mL measuring
cup. This provides 1016 kcal/day and is the resting energy
requirement for a 35 kg dog, which is estimated to be
Jodie’s ideal body weight. Resting energy requirement
(RER) can be calculated using the formula: RER (kcal/day)
= 70 x (body weight in kg)0.75 (Editor’s note: practitioners
without scientific calculators can calculate BW0.75 by using
the following formula: BWxBWxBW, enter, and then ␯␯).
A portion of the meals can be set aside to be fed as snacks
throughout the day.
Physical activity: As Jodie is very exercise intolerant, it is
emphasized that exercise should be limited to what she
can manage comfortably.
Outcome:
Over the first 8 weeks of the obesity management
program, Jodie has lost just 700g and her body weight
has reduced by only 1.6% to 44.0 kg. However, her body
condition score has decreased by a greater proportion to
7.5/9 (4.25/5), and progressive reduction of neck and
waist circumference has occurred. Exercise intolerance
and respiratory signs have resolved and she is able to
resume 30-minute walks. Otitis externa is still present
but signs are adequately controlled with topical therapy.
The greatest concern for the owners is that Jodie does not
always eat all of her morning meal. They feel that the
prescription diet is not sufficiently palatable and frequently
seek advice on strategies to improve palatability. They
believe that she is usually hungry because she always begs
for treats when they are eating. They choose not to use a
portion of the usual meals as snacks throughout the day
because they believe that Jodie will not want these.
Reinforcement of the importance of persisting with a strict
elimination food trial is provided on several occasions.
Great emphasis is also placed on the overall improvement
in Jodie’s quality of life, with resolution of exercise
intolerance and respiratory signs, and resumption of her
usual walks. It is explained that appetite can be stimulated
in satiated dogs by offering highly palatable food, and that
begging for food is a manifestation of the human-animal
bond, as well as an expression of hunger. The owners are
encouraged to reflect on their own appetite with regard to
different food items. Most people relish a healthy
sandwich when hungry, yet decline to eat a similar
sandwich when not hungry. Chocolate cake, on the other
hand, is often desired and consumed by people even when
they are not hungry. When this analogy is applied to Jodie,
the prescription diet is likened to healthy sandwiches that
are eaten well when the dog is hungry and refused when
she is satiated, while pieces of cheese can be considered as
palatable as chocolate cake.
Food intake is reduced to 1 cup of the prescription
hydrolyzate diet in the morning and 2 cups in the evening
(760 kcal/day). These results in all of the food being
consumed at most meals. At the end of the elimination
food trial when there is no apparent improvement in the
otitis externa, Jodie’s owners are keen to change to a diet
with improved palatability and decreased calorie density
compared with the hydrolyzate diet. Two options are
trialed and the owners choose a prescription dry food
formulated for obesity management (ME: 3.02 kcal/g).
Recommended calorie intake is 700 kcal/day fed as two
separate meals. The otitis externa is carefully monitored
after the dietary change and no clinical deterioration is
noted. Regular reassessment is continuing and Jodie’s
body weight and body condition are both progressively
decreasing.
Comments:
In this case, the most important issue is to provide
education and support for the owners of the dog. At the
initial consultation, Jodie’s owners had no comprehension
that she was being fed too many calories for her energy
needs, or that a hydrolyzate diet is not meant to be
supplemented with other foods such as cheese. An understanding of the nutritional needs of their pet is required
for feeding guidelines to be effectively implemented. In
addition, ongoing support is needed because the owners
find it emotionally difficult to stop sharing a portion of
their own food with Jodie.
Case 2: Toby
Management strategy: changing the feeding method
Signalment:
• 5 year old, neutered male, Cavalier King Charles Spaniel
Body weight = 16.4 kg
Body condition score = 7.5/9 (4.25/5)
Diet history:
Food: Toby’s staple diet is a nutritionally complete and
balanced, grocery brand dry food, marketed as having a
“lite” formulation for adult canine maintenance (ME:
3.54 kcal/g). He is also frequently fed snacks, including
commercial dog treats (ME: 3.59 kcal/g), table scraps,
and pieces of cheese.
Feeding method: A free-choice feeding method is used
for Toby’s dry food. His bowl is topped up from a
nearby storage container whenever the bowl is nearly
empty. It is changed once daily for a clean bowl, and the
dry food transferred. Snacks are fed by all family
2006
l
Vol 16 No 1
WALTHAM Focus
11
members at the dinner table, at afternoon tea, and when
they visit the pantry. Toby is also fed commercial dog
treats and occasional pieces of cheese for good behavior
or because he exhibits begging behavior to a family member.
Lifestyle:
Toby is described as having a moderately sedentary
activity level. He is usually exercised two to three times
weekly for 30 minutes, but this has been reduced
recently because of lameness due to osteoarthritis.
Specific owner and dog constraints identified for this
case:
Toby’s owners believe that he is a very finicky eater
because he often will not eat his dry food. They say that
he always prefers to eat a portion of their food. They
admit that they all find it impossible to resist his
pleading expression when he begs for food.
Obesity management has been recommended because
Toby has chronic lameness due to osteoarthritis.
Food: The nutritionally complete and balanced, “lite”,
grocery brand dry food is to be continued. Additional
food is to be restricted to the commercial dog treats.
Feeding method: Daily calorie intake will be restricted to
450 kcal. This is the resting energy requirement for a 12
kg dog, which is estimated to be Toby’s ideal body weight.
One adult member of the household will precisely
measure 120 g of the food each day and place it in a
container. One of the commercial dog treats will be
broken into pieces and added to the ration. Family
members may then use the food in the container to
provide as many small meals and snacks throughout the
day for Toby as they wish. No additional food is to be fed.
Physical activity: Toby is to be walked every day, rather
than two or three times a week. The aim is for a 30minute walk every day, but the duration of the walk may
be reduced if lameness is apparent.
Outcome:
The owners report that the container with Toby’s daily ration of
food has become a major focus in the household. Toby soon
refuses to eat any food from a bowl. Instead, the owners are
required to hand feed individual kibbles of the food throughout
the day. Toby develops the behavior of carrying each kibble of
food to another room or outside the house before eating it. He
then returns and begs for the next kibble. The owners believe
that Toby enjoys this method of feeding and admit that they do
as well. Their only concern is that they believe that the daily
ration is too small and they run out of food each evening.
12
WALTHAM Focus
Vol 16 No 1
l
2006
During the first 4 weeks, Toby loses 1.8 kg, which represents
2.7% weight loss per week. This rate of reduction is
considered excessive because generally the objective is to
achieve an average of 1-2% weight loss per week. The daily
ration is increased to 160 g of the grocery brand food. The
commercial dog treats are discontinued because the owners
are no longer interested in feeding them.
Weight loss then proceeds steadily at a rate of
approximately 1.5% per week and after a further 4 months
Toby reaches ideal body condition at 11.8 kg. The quantity
of the daily ration is then adjusted to maintain this.
Comments:
The companion animal-human bond plays a crucial role
in obesity management programs for pets. Owners are
often concerned that calorie restriction will be an
important welfare issue. They believe that they will be
depriving their pet if they do not give the animal food
when it appears to be hungry. Significant owner
pleasure is obtained from feeding Toby and this issue
needs to be addressed. Successful obesity management is
achieved in this case by changing the free-choice feeding
method to one that involves maximum interaction
between dog and owners.
Case 3: Moppet and Mittens
Management strategy: changing the type of food
Signalment:
• Two year old, neutered female, Burmese cats (Figures 2)
• Moppet and Mittens are littermates that live together
in the one household
Moppet: Body weight = 7.7 kg; Body condition score =
8.5/9 (4.75/5)
Mittens: Body weight = 8.2 kg; Body condition score =
9/9 (5/5)
Diet history:
Food: Both cats are fed a nutritionally complete and
Figures 2.
Moppet and Mittens are two
year old, neutered female,
Burmese cats. They are
littermates that live together
in the one household. Before
the obesity management
program, Moppet had a body
condition score of 8.5/9
(4.75/5), while Mittens had a
body condition score of 9/9 (5/5).
Photos provided by Dr Annette L.
Litster of the School of Veterinary
Science, the University of
Queensland, Australia.
balanced, premium dry food formulated for maintenance
of less active, adult cats (ME: 4.28 kcal/g). No treats or
other foods are fed.
Feeding method: The client who presented the cats for
assessment is the only person in the household who feeds
the cats. Food is supplied in two bowls. One bowl is on
the floor and is used by both cats. The other bowl is on a
bench and can only be accessed by Moppet. This is a
strategy introduced by the owner to reduce weight gain
in Mittens, who is the heavier cat and can no longer jump
on to the bench to feed from the bowl there. A freechoice feeding method is used. Food is added to the
bowls twice daily. Every 2-3 days, the food in the bowls is
discarded, the bowls are cleaned, and fresh food is
supplied. The owner has no idea how much food each cat
consumes each day.
Lifestyle:
Both cats are kept indoors and their activity level is
described as sedentary.
Specific owner and cat constraints identified for this case:
The owner is unwilling to attempt a change from a freechoice feeding method to a food-restricted meal feeding
method, as this will not suit her lifestyle. She also
believes that it will not be easy to increase the activity
level of the cats because both animals are reluctant to
engage in games that involve stalking, chasing, pouncing,
or swatting.
Burmese cats have an increased risk for developing
diabetes mellitus (3, 4), particularly those that are
confined indoors or have lower physical activity (5).
The risk for developing diabetes is further increased in
cats by obesity-induced insulin resistance and
hyperinsulinemia (6). For Moppet and Mittens, successful
weight management will reduce the risk for developing
diabetes later in life.
Food: Change the food to a nutritionally complete and
balanced, prescription dry food with restricted dietary
carbohydrate content. The recommended diet has lower
calorie density (3.96 kcal/g) and greatly reduced dietary
carbohydrate content (13%ME), compared with the
previous diet (ME 4.28 kcal/g; carbohydrate content
37%ME).
Feeding method: Initially, the recommendation is to
continue using the free-choice feeding method as the
owner is reluctant to change this. A meal feeding
method might be required if obesity management is not
successful with continued free-choice feeding. The
owner is encouraged to quantify the amount of food
consumed by the cats each day as this information will
help to determine the appropriate meal size if the
feeding method is to be changed.
Physical activity: Several options for increasing physical
activity of the cats are discussed and a range of potential
toys shown as examples. As the cats are reluctant to
engage in direct play with the owner, the suggestion is
made that favored items and portions of food be
distributed throughout the house when the owner leaves
for work for the cats to ‘discover’ during the day.
Outcome:
Gradual reduction in body weight and body condition is
sustained in both cats over the following 7 months. At
each reassessment, the owner reports that she has not
been able to quantify the amount of food consumed by
the cats each day but that they don’t seem to be eating as
great a volume of food as they had previously. She is
very pleased with the outcome because she has been able
to continue using the free-choice feeding method. The
owner also reports that one of the cats, Mittens, has
become very bonded to one particular toy, and will seek
out the toy, play with it, carry it around in her mouth,
and sleep with it near her.
After 7 months, both cats achieve ideal body condition
[5/9 (3/5)] and weigh 5.8 kg and 5.5 kg, respectively
(Figures 3). No changes are made to the feeding
regimen, and further reassessment identifies stable body
weight and condition over the next 6 months.
Comments:
In this case, the risk for developing diabetes mellitus is
considered much greater than average. The frequency of
diabetes in the Burmese breed is approximately four
times the rate in Domestic cats in Australia; with 1 in 50
Burmese affected compared with less than 1 in 200
Domestic cats (7). The risk for Mittens and Moppet was
likely further increased by the effects of excess body fat
because many obese cats are glucose intolerant and
hyperinsulinemic (6). Thus, nutritional intervention to
lower postprandial glucose and insulin concentrations
by restricting dietary carbohydrate intake was considered
important (8).
When the diet was changed from a premium dry food
formulated for maintenance of less active, adult cats, to a
prescription dry food with restricted dietary carbo-hydrate
content, the apparent food intake of the cats decreased and
gradual reduction of body weight and condition to ideal
was achieved despite continued free-choice feeding. This
might have been because the low carbohydrate, high
2006
l
Vol 16 No 1
WALTHAM Focus
13
protein prescription diet was associated with greater satiety.
Alternatively, the cats might have found this diet less
palatable than the premium food.
weight loss per month. The owner feels that the cat is
always hungry and is not prepared to further restrict
calorie intake because she believes that this will
negatively affect Holly’s quality of life.
Case 4: Holly
Management strategy: increasing activity level
Signalment:
• 7 year old, neutered female, Domestic Shorthair cat
Body weight = 7.6 kg
Body condition score = 8/9 (4.5/5)
Diet history:
Food: The staple diet is a prescription, restricted-calorie,
dry food formulated for weight loss (ME: 3.02 kcal/g).
Occasionally, a treat comprising a single kibble of the
other cat’s premium, hairball control, dry food is fed
(ME: 3.89 kcal/g).
Feeding method: 50-60 g of food divided into 4 meals
per day. The presenting owner is the person who feeds
the cat and carefully measures the portion of food each
day. All food is always consumed immediately.
Although the two cats in the household are fed
separately, Holly occasionally manages to steal 5-6
kibbles of the hairball control food.
Lifestyle:
Holly is kept indoors and her activity level is described as
sedentary.
Specific owner and cat constraints identified for this case:
The owner has been following an obesity management
program for Holly for 15 months and is frustrated
because the rate of weight loss is too slow. Since starting
the program, Holly has lost 1.1 kg, which is less than 1%
Figures 3.
The diet fed to Moppet and
Mittens was changed to a
prescription dry food with
restricted dietary
carbohydrate content, which
was fed using a free-choice
feeding method. The
apparent food intake of the
cats decreased and over 7
months there was gradual
reduction of body condition
to ideal. Ideal body
condition [5/9 (3/5)] in cats
is characterized by a wellproportioned silhouette with
a clearly identifiable waist
when viewed from above.
Photos provided by Dr Annette L. Litster of the School of Veterinary Science, the University of
Queensland, Australia.
14
WALTHAM Focus
Vol 16 No 1
l
2006
Food: No change
Feeding method: No change
Physical activity: Options for increasing physical activity
are discussed and a range of potential toys shown as
examples. It is explained that the key is to encourage
playful, kitten-like behavior. Cats tend to like to stalk,
ambush, and pounce when playing. Devices that
resemble a fishing rod with a toy dangling at the end are
popular for exercising cats, as are items secured at the
end of a piece of wire that flexes in an erratic and
unpredictable manner. Another simple method involves
blowing bubbles for the cat to chase using a child’s
bubble-ring and soapy water. Some cats can be easily
encouraged to follow their owner around the house for 5
15 minutes per day. It is not necessary for the cat to be
constantly moving throughout the exercise period.
Physical activity in cats naturally occurs in sporadic
stops and starts. Children often enjoy being given the
task of exercising a cat.
Outcome:
There was initially some difficulty with encouraging
Holly to increase her activity level, and she could not be
engaged in playing with any of the toys. Eventually a
game was found that Holly seemed to enjoy. Holly’s
owner named this game “bed mice” and described that
when she moved her hand under the bed covers while
the cat was on top of the covers, Holly could be
encouraged to chase and pounce on the hand. This
game was played for 5-15 minutes each day, and after a
few weeks, the owner reported that the cat’s general
activity level and interest in life seemed to improve.
Holly appeared to look forward to the game and would
sit at the door to the bedroom waiting for the owner to
come and play.
During the following 12 months, Holly doubled her rate
of weight loss, and achieved ideal body condition at a
body weight of 5.7 kg.
Comments:
Recent research indicates that daily exercise of the type
described here is an effective means of managing obesity
in cats, and can be used alone or in conjunction with
calorie restriction (9-11). Additional benefits of
incorporating play activity into the daily routine include
the introduction of a form of owner-cat interaction that
does not involve feeding, and the perception by the
owner that their cat’s quality of life is improved.
Conclusion
These four cases illustrate how obesity management
programs can be individualized for dogs and cats.
Success relies on accurate collection of a detailed diet
history, honest communication about lifestyle,
identification of specific owner and pet constraints, and
ongoing support and guidance. Consideration of the
individual companion animal-human bond is always
very important. Developing regimens that work within
the constraints of this bond and are easy for owners to
implement make for longer-term success. If the specific
limitations of each case are addressed in this manner,
motivation and compliance are optimized. Ultimately,
the key is to find the most practical balance between
increasing daily energy expenditure and decreasing daily
consumption of calories. u
references
1. Laflamme DP. Development and validation of a body condition score
system for dogs. Canine Practice 1997; 22: 10-15.
2. Loeffler A, Lloyd DH, Bond R, et al. Dietary trials with a commercial
chicken hydrolysate diet in 63 pruritic dogs. Vet Rec 2004; 154: 519-522.
3. Rand JS, Bobbermien LM, Hendrikz JK, et al. Over representation of
Burmese cats with diabetes mellitus. Aust Vet J 1997; 75: 402-405.
4. Wade C, Gething M, Rand JS. Evidence of a genetic basis for diabetes
mellitus in Burmese cats (Abstract). J Vet Intern Med 1999; 13: 269.
5. Lederer R, Rand JS, Hughes IP, et al. Chronic or recurring medical
problems, dental disease, repeated corticosteroid treatment, and lower physical
activity are associated with diabetes in Burmese cats (Abstract). J Vet Intern
Med 2003; 17: 433.
6. Rand JS, Fleeman LM, Farrow HA, et al. Canine and feline diabetes:
Nature or nurture? J Nutr 2004; 134: 2072S-2080S.
7. Baral RM, Rand JS, Catt MJ, et al. Prevalence of feline diabetes mellitus in
a feline private practice (Abstract). J Vet Intern Med 2003; 17: 433.
8. Farrow HA, Rand JS, Sunvold GD. Diets high in protein are associated
with lower postprandial glucose and insulin concentrations than diets high in
either fat or carbohydrate in normal cats (Abstract). J Vet Intern Med 2002;
16: 360.
9. Giles R, Gruffydd-Jones TJ, Sturgess CP. A preliminary investigation into
the effect of different strategies for achieving weight loss in cats (Abstract).
Proceedings British Small Animal Veterinary Association (BSAVA) Congress
2003; 546.
10. Trippany JR, Funk J, Buffington CAT. Effects of environmental
enrichments on weight loss in cats (Abstract). J Vet Intern Med 2003; 17: 430.
11. Clarke DL, Wrigglesworth D, Holmes K, et al. Using environmental and
feeding enrichment to facilitate feline weight loss (Abstract). Proceedings
American Academy of Veterinary Nutrition (AAVN) Clinical Nutrition and
Research Symposium 2005; 4.
2006
l
Vol 16 No 1
WALTHAM Focus
15
Techniques to assess body
composition in dogs and cats
Denise A. Elliott BVSc (Hons), PhD, Dipl ACVIM, Dipl. ACVN
Director of Scientific Communications Royal Canin USA
Denise Elliott graduated from the University of Melbourne with a Bachelor in Veterinary Science with Honors in
1991. After completing an internship in Small Animal Medicine and Surgery at the University of Pennsylvania,
Denise moved to the University of California-Davis where she completed a residency in Small Animal Medicine, a
fellowship in Renal Medicine and Hemodialysis, and a residency in Small Animal Clinical Nutrition. Denise
received board certification with the American College of Veterinary Internal Medicine in 1996 and with the
American College of Veterinary Nutrition in 2001. The University of California-Davis awarded a PhD in Nutrition in 2001 for her
work on Multifrequency Bioelectrical Impedance Analysis in Healthy Cats and Dogs. Denise is currently the Director of Scientific
Communications for Royal Canin USA.
Introduction
Obesity is the most prevalent form of malnutrition in
veterinary medicine. Surveys suggest that 25% to 30%
of dogs and cats presented to veterinary clinics are
overweight (1-3). Obesity is defined as a pathological
condition characterized by an accumulation of fat in
excess of that required for optimal body function. The
significance of obesity pertains to its role in the
pathogenesis of a variety of diseases and the ability to
exacerbate pre-existing disease (4). The ability to
accurately measure body fat would facilitate
understanding the causes and effects of obesity and the
response to weight reduction programs.
Numerous methods exist for the assessment of body
composition (Table 1). However, techniques including
densitometry, total body potassium, and neutron
activation analysis are not readily available and the
remainder of this discussion will focus on clinically
relevant methods.
Body weight can be subdivided into two or more
Table 1.
Techniques available to measure body composition
Clinically relevant techniques
• Body weight
• Body condition score
• Morphometric measurements
• Body Mass Index
• Dilutional techniques
• Bioelectrical impedance analysis
• Dual energy x-ray absorptiometry
16
WALTHAM Focus
Vol 16 No 1
l
Research techniques
• Densitometry
• Computed tomography
• Magnetic resonance imaging
• Total body electrical conductivity
• Total body potassium
• Neutron activation analysis
2006
physiologically distinct components (Figure 1). The
traditional two compartment model divides body
weight into the fat mass (FM) and the fat free mass
(FFM) (5, 6). This model forms the basis of the
majority of our current knowledge of body
composition, and is dependent upon assumptions
regarding the character of the FM and the FFM
(Table 2). The composition of the FFM is assumed to
be relatively constant with a density of 1.1 g/mL at
37oC, a water content of 72-74%, and a potassium
content of 50-70 mmol/kg (7). In addition, the major
constituents of the FFM are presumed to be present in
fixed ratios. In comparison, the FM is relatively
homogenous in composition, anhydrous and
potassium free with a density of 0.900 g/mL at 37oC.
The assessment of body composition in the form of
FM and FFM provides valuable information about
the physical and metabolic status of the individual.
The FM can be considered to represent a calorie or
Table 2.
Assumptions used to assess body composition
Fat Free Mass
• Heterogeneous
• Intracellular water, extracellular
water, minerals, glycogen
• Density of 1.1 g/mL
• Water content 72-74%,
• Potassium 50-70 mmol/kg
Fat Mass
• Homogenous
• Anhydrous
• Potassium free
• Density of 0.9g/mL
Techniques to Assess Body Composition
energy storage depot. Conversely, the FFM represents
the actual health of the animal. It is a heterogeneous
entity consisting predominantly of intracellular (ICF)
and extracellular fluid (ECF), minerals, glycogen and
protein. The FFM contains the body cell mass (BCM),
which is the metabolically active part of the body
responsible for determining most of the resting energy
expenditure. BCM encompasses those lean tissues most
likely to be affected by nutrition or disease over relatively
short periods. Furthermore, the FFM is generally
accepted as an index of protein nutrition and therefore
changes in FFM over time are assumed to represent
alterations in protein balance.
Body weight
Body weight is the simplest technique and should be
included in the examination of every patient. It provides
a rough measure of total body energy stores and changes
in weight parallel energy and protein balance. In the
healthy animal, body weight varies little from day to day.
There can be wide variation between scales though, so it
is important to use the same scale for an individual
animal each time to avoid inter-scale variation. The
major problem with body weight is that by itself, it has
BODY WEIGHT
Minerals
FAT
FREE
MASS
Extracellular
Water
Intracellular
Water
Glycogen
Protein
WATER
ENERGY
FAT MASS
DEXA Fat Mass
Figure 1.
Composition of the body.
Rottweiller
German Shepherd dog
Golden Retriever
Labrador Retriever
little meaning. Knowing that a Labrador Retriever
weighs 31.76 kg (70 pounds) means little; the dog could
be overweight, underweight, or in ideal body condition.
Therefore, body weight should not be used in isolation.
Body condition score
The body condition score (BCS) provides a quick and
subjective assessment of an animal’s overall body
condition. The two most commonly used scoring
systems in small animal practice are a 5-point system
where a BCS of 3 is considered ideal or a 9-point system
where a BCS of 5 is considered ideal. The BCS in
conjunction with body weight gives a clinician a more
complete perspective on a patient’s body condition and
should be recorded in the medical record at every visit.
Limitations of the BCS include the subjectivity inherent
in the scoring system (Figure 2) and interobserver
variation. Finally, like body weight, BCS gives an overall
assessment of body condition; it cannot differentiate
between body compartments and does not provide any
precise quantitative information concerning alteration
in fat free or lean body mass relative to fat mass.
Morphometric measurements
Height and circumferential measurements of the abdomen,
hip, thigh and upper arm are commonly used to estimate
percent body fat in humans. Circumferential measurements
have also been developed to estimate the percent body fat in
cats (8). The Feline Body Mass Index™ (FBMTTM) is
determined by measuring the rib cage circumference at the
level of the 9th cranial rib (Figure 4) and the leg index
measurement (LIM), which is the distance from the patella
to the calcaneal tuber (Figure 3). The percent body fat can
be calculated as 1.5 (ribcage - LIM)/9, or determined by
consulting a reference chart (Figure 5). Cats with more
than 30% body fat are candidates for a weight loss program.
The FBMI™ is a very simple, yet objective tool to
determine the body fat content of the cat. In addition, it is
particularly valuable for convincing clients that their cat is
indeed overweight and in need of weight loss. Pelvic
Body Conditions Score
Figure 2.
Comparison between body condition score as assessed by one operator, and percent
body fat determined by dual energy x-ray absorptiometry (DEXA) in 20 adult
dogs. The subjectivity of the body condition score system is highlighted by the
range of body condition scores assigned to dogs with similar percent body fat.
Figure 3.
The length of the lower leg (LIM)
from the middle of the patella.
2006
Figure 4.
Measurement of the rib cage
circumference.
l
Vol 16 No 1
WALTHAM Focus
17
Rib Cage circumference
Overweight
Normal Weight
Underweight
Leg Index Measurement (LIM in cm)
Figure 5. The Feline Body Mass Index chart.
circumference and distance from hock to stifle has been
shown to predict body fat in dogs (9).
The measurement of skin-fold thickness has been used
extensively in people to determine the percent body fat
using equations derived for various populations. This
estimate is based on the relationship between thickness of
subcutaneous fat layer and total body fat. Unfortunately,
these measurements cannot be used in dogs and cats
because canine and feline skin is easily detached from
underlying fat tissue, which makes skin-fold
measurement impractical and unreliable in these species.
Another method of measuring the subcutaneous fat layer is
by ultrasound. This technique has been used experimentally
in Beagles and equations have been derived to predict
percent body fat from the subcutaneous fat thickness (10).
These regression equations do not work in other dog breeds
but future research may allow investigators to develop new,
more accurate equations for this simple technique.
Dilutional techniques
Total body water (TBW)
Dilutional techniques rely on the principal of C1V1 =
C2V2, that is, the volume of a biological fluid can be
calculated following the administration and equilibration
of a known concentration of tracer. The tracer
administered should be non-toxic, non-metabolizable, and
easy to administer, and have the same distribution volume
as the fluid under investigation. The TBW method relies
on the assumption that fat has negligible water content
and the FFM has fairly constant and known water content
(73%). FFM can be calculated as TBW/0.73 and since
body weight = Fat + FFM, an estimation of body
composition can be made.
18
WALTHAM Focus
Vol 16 No 1
l
2006
Isotopes of hydrogen (deuterium (D2O) and tritium
(3H2O)), urea, alcohol, N-acetyl-4-aminopyrine and
H2O18 distribute in the TBW compartment and have
been employed to quantify TBW. The approach used in
most laboratories is dilution of the stable isotopes D2O
or H2O18. These techniques have been successfully
completed in dogs (11, 12) and cats (13) and are
appropriate for non-invasive studies, however they do
require expensive analytical equipment. Deuterium and
tritium undergo some exchange with non-aqueous H+
and hence can overestimate TBW by 3-5%. Similarly,
18O will exchange with labile oxygen atoms and hence
can overestimate TBW by 0-1%. Consideration also
needs to be given to urinary and respiratory losses of
isotope. TBW can be measured with a precision and
accuracy of 1-2%. The potential concern with this
technique is the assumption of the hydration factor,
which may change with age, sex, species, breed or
disease (14).
Extracellular fluid (ECF)
ECF is an important physiological component of total
body water that can be altered in illness. ECF can be
measured by use of compounds including inulin,
35S O3-, 35SO 2-, SCN-, Br-, and 82Br- that distribute
2
4
within the extracellular space. However ECF markers
may not distribute uniformly in the sub-compartments
of the ECF (plasma, interstitium, lymph, connective
tissue), some markers penetrate cells to an extent that
can not be precisely determined, or they may bind to
some degree to endogenous components. Bromide is
the most useful, safest, and widely used tracer for
determination of ECW volume (15). Determination
requires high performance liquid chromatography
(HPLC) and correction factors can be applied to
account for the Donnan equilibrium, serum water, and
distribution in non-extracellular sites. Simultaneous
measurement of ECF and TBW enables the estimation
of intracellular water volume (ICW), i.e. ICW = TBW ECW. ICW volume most closely approximates BCM.
Bioelectrical impedance analysis (BIA)
Bioelectrical impedance analysis is an electrical method
of assessing body composition that has the potential of
quantifying TBW, ECW, ICW, BCM, FFM and FM.
Electrical conductance is used to calculate the
composition of the body by measuring the nature of the
conductance of an applied electrical current in the
patient. Body fluids and electrolytes are responsible for
conductance whilst cell membranes produce
capacitance. Since adipose tissue is less hydrated than
lean body tissues, more adipose tissue results in a smaller
conducting volume or path for current and larger
electrodes. Low frequencies (e.g. 5 kHz) pass primarily
through the ECW because of high cell membrane
capacitance. In contrast, at higher frequencies the effects
of cell membrane capacitance is diminished so the
current flows through both the ICF and ECF
environments (or TBW). The proportion of the current
in the ICF and ECF is frequency dependent (Figure 7).
Figure 6.
Multi-frequency bioelectrical impedance analysis on a dog.
BIA
Electrodes
High Frequency
Current
Low Frequency
Current
ICF
ECF
Cells
Figure 7.
Electrode placement and theory underlying multi-frequency bioelectrical
impedance analysis. Low frequency current passes primarily through the
extracellular fluid (ECF) whereas high frequency current flows through both the
intracellular (ICF) and extracellular fluid environments.
Figure 8.
Dual-energy X-ray absorptionometry (DXA)
prior to weight loss revealed body fat content of
42% (reference range 20 to 35%).
impedance to current passage.
The FFM contains virtually all
the water in the body and thus if
bioelectrical
impedance
is
measured a value for FFM can be
determined.
Two types of BIA systems are
currently
available;
single
frequency, which applies a 50
kHz current, and multi-frequency, which utilizes
frequencies from 5 kHz to 1000 KHz. A BIA test is
performed by placing four small electrodes on the body
(Figure 6). The electrical current is introduced into the
patient from the distal electrodes. As the current travels
through the body it experiences a slight delay due to
cells, and the current is then detected by proximal
BIA may be affected by hydration status, consumption
of food and water, skin and air temperature, recent
physical activity, conductance of the examination table,
patient age, size, shape and posture in addition to
electrode positioning.
Reliable BIA requires
standardization and control of these variables. BIA
requires further evaluation and validation in disease
states, especially those associated with major
disturbances in water distribution and states such as
sepsis, which may alter cell membrane capacitance. It
has however, been shown to be a safe, noninvasive,
rapid, portable, and reproducible method to estimate
body composition in healthy dogs, cats, and humans
(16-19). Calculation of ECF-ICF takes approximately
1 minute, hence BIA provides instantaneous on line
information of body composition that has never before
been available.
Dual energy X-ray absorptiometry
Dual-energy x-ray absorptiometry (DEXA) is a technique originally developed for precise measurement of
bone mineral content (BMC). However, it is now also
used to measure both body fat and non-bone lean tissue.
DEXA uses photons of two different energy levels (70
and 140 kVp) to distinguish the type and amount of
tissue scanned. The X-ray source is positioned
underneath the table supporting the patient, with the
detector housed in an arm above the patient (Figure 8).
During a scan the source and detector move together
over the patient. The detector measures the amount of
X-rays that pass through the subject. The X-rays of the
two different energy levels are impeded differently by
bone mineral, lipid and lean tissue. Algorithms are used
to calculate both the quantity and type of tissue in each
pixel scanned. DEXA calculates bone mineral density
(BMD), bone mineral content (BMC), fat mass, and
lean body mass.
DEXA’s low coefficient of variation for measuring BMC
(~1%) makes it a very precise technique. DEXA also is
safe and quick, requiring 10-30 minutes for a whole
body scan. Similar to other body composition
techniques, DEXA relies on the assumption that lean
body mass is uniformly hydrated at 0.73 mL water/g.
2006
l
Vol 16 No 1
WALTHAM Focus
19
Summary
The ideal body composition method should be accurate,
safe, inexpensive, rapid, reliable, highly reproducible,
and easy to operate. Methods that have clinical
application include body weight, body condition
scoring, morphometric measurements, dilution studies,
bioelectrical impedance analysis and dual energy x-ray
absorptiometry. Regardless of the technique selected, it
is imperative to meticulously follow established
protocols to limit measurement error. The ability to
accurately measure body fat and fat free mass (lean body
mass) is vital for understanding the causes and effects of
obesity. In addition, these techniques allow critical
appraisal of the effect of nutrient composition on body
composition. u
references
1. Edney AT, Smith PM. Study of obesity in dogs visiting veterinary practices
in the United Kingdom. Vet Record 1986; 118: 391-6.
2. Mason E. Obesity in pet dogs. Vet Record 1970; 86: 612-6.
3. Scarlett JM Donaghue S. Overweight cats-prevalence and risk factors.
Intern J Obes 1994; 18: S22-S28.
4. Scarlett JM, Donaghue S. Associations between body condition and disease
in cats. J Am Vet Med Assoc 1998; 212: 1725-31.
5. Keys A, Brozek J. Body fat in adult man. Physiol Rev 1953; 33: 245-325.
6. Brozek J, Grande F, Anderson JT, et al. Densitometric analysis of body
composition: revision of some quantitative assumptions. Ann N Y Acad Sci
1963; 113-140.
7. Pace N, Rathbun EN. Studies on Body Composition III. The body water
and chemically combined nitrogen content in relation to fat content. J Biol
Chem 1945; 158: 685-691.
8. Hawthorne AJ, Butterwick RF. Predicting the body composition of cats:
development of a zoometric measurement for estimation of percentage body
fat in cats. J Vet Inter Med 2000; 14: 365.
9. Burkholder WJ. Body composition of dogs determined by carcass
composition analysis, deuterium oxide dilution, subjective and objective
morphometry and bioelectrical impedance, Blacksburg, Virginia Polytechnic
Institute and State University 1994.
10. Wilkinson MJ, McEwan NA. Use of ultrasound in the measurement of
subcutaneous fat and prediction of total body fat in dogs. J Nutr 1991; 121:
s47-50.
11. Zweens J, Frankena H, Reicher A, et al. Infrared-spectrometric
determination of D2O in biological fluids. Reappraisal of the method and
application to the measurement of total body water and daily water turnover in
the dog. Pflugers Archiv 1980; 385: 71-77.
12. Burkholder WJ, Thatcher CD. Validation of predictive equations for use
of deuterium oxide dilution to determine body composition of dogs. Am J Vet
Res 1998; 59: 927-937.
20
WALTHAM Focus
Vol 16 No 1
l
2006
13. Backus RC, Havel PJ, Gingerich RL, et al. Relationship between serum
leptin immunoreactivity and body fat mass as estimated by use of a novel gasphase Fourier transform infrared spectroscopy deuterium dilution method in
cats. Am J Vet Res 2000; 61: 796-801.
14. Wang Z, Deurenberg P, Wang W, et al. Hydration of fat-free body mass:
review and critique of a classic body-composition constant. Am J Clin Nutr
1999; 69: 833-41.
15. Vaisman N, Pencharz PB, Koren G, et al. Comparison of oral and
intravenous administration of sodium bromide for extracellular water
measurements. Am J Clin Nutr 1987; 46: 1-4.
16. Patel RV, Matthie JR, Withers PO, et al. Estimation of total body and
extracellular water using single- and multiple-frequency bioimpedance. Ann
Pharmacother 1994; 28: 565-569.
17. Scheltinga MR, Helton WS, Rounds J, et al. Impedance electrodes
positioned on proximal portions of limbs quantify fluid compartments in dogs.
J Appl Physiol 1991; 70: 2039-2044.
18. Elliott DA. Evaluation of Multifrequency Bioelectrical Impedance
Analysis for the Assessment of Total Body Water and Extracellular Water in
Healthy Cats and Dogs. PhD thesis, University of California-Davis 2001.
19. Stanton CA, Hamar DW, Johnson DE, et al. Bioelectrical impedance and
zoometry for body composition analysis in domestic cats. Am J Vet Res 1992;
53: 251-257.
20. Pritchard JE, Nowson CA, Strauss BJ, et al. Evaluation of dual energy Xray absorptiometry as a method of measurement of body fat. Eur J Clin Nutr
1993; 47: 216-228.
21. Son HR, d'Avignon DA, Laflamme DP. Comparison of dual-energy x-ray
absorptiometry and measurement of total body water content by deuterium
oxide dilution for estimating body composition in dogs. Am J Vet Res 1998;
59: 529-32.
22. Van Loan MD, Mayclin PL. Body composition assessment: dual-energy
X-ray absorptiometry (DEXA) compared to reference methods. Eur J Clin
Nutr 1992; 46: 125-130.
Clinical risks associated with
obesity in companion animals
Alex German, BVSc(Hons), PhD, CertSAM, DipECVIM-CA, MRCVS
Head of the Internal Medicine/Gastroenterology Services, Lecturer in Small Animal Medicine, Director of the
Royal Canin Weight Management Clinic, University of Liverpool, UK
Alex German qualified, with honors, from the University of Bristol (UK) in 1994. After two years in mixed practice
he returned to Bristol to undertake a PhD in canine mucosal immunology, and then a residency in small animal
internal medicine. He attained the RCVS certificate in small animal medicine in August 2001, and became a
Diplomat of the European College of Veterinary Internal Medicine in September 2004. He is currently the Royal
Canin Lecturer in Small Animal Medicine at the University of Liverpool, and also Director of the Royal Canin Weight Management
Clinic, the UK’s first referral service for obesity biology. His research interests include all aspects of small animal internal medicine,
gastroenterology, comparative obesity biology, and clinical metabolomics.
KEY POINTS
Á Obesity is one of the major current medical concerns
of companion animals
Á Increased adiposity has numerous clinical
consequences, most notably through predisposing
to medical conditions such as diabetes mellitus,
osteoarthritis, respiratory disease and neoplasia
Á White adipose tissue (WAT) is an active endocrine
organ, and secretes many factors (‘adipokines’)
which can have a regulatory effect on many
body systems
Á Disruption of the normal endocrine function of WAT
is now recognized as a major pathogenic mechanism
for the development and exacerbation of many
of the obesity-associated disorders
Introduction
Obesity is defined as an accumulation of excessive
amounts of adipose tissue in the body (1), and has
been defined as a greater than 15% increase above
the ideal body weight for the individual. Obesity is
an escalating global problem in humans, and current
estimates suggest that almost two thirds of adults in
the United States are overweight or obese. Studies,
from various parts of the world, have estimated the
incidence of obesity in the pet population to be
between 22% and 40% (2). Most investigators
agree that, as in humans, the incidence in the pet
population is increasing. The most recently
published data comes from a large study in Australia,
where 33.5% of dogs were classed as overweight,
whilst 7.6% were judged to be obese (2).
Human obesity is known to be associated with
increased risk of type II diabetes mellitus (DDMII),
cancer, cardiac disease, hypertension, and decreased
longevity. Similarly, obesity has detrimental effects
on health and longevity of dogs and cats (Table 1),
although data are more limited. Some studies do
suggest an increase in morbidity in sick patients
with poorer body condition in dogs (3). Evidence
in cats also suggests increase health risks in obese
individuals (4). This article will review the various
clinical risks, which are known to be associated with
obesity in companion animals, and also discuss the
role that the adipose tissue itself plays in disease
pathogenesis.
Clinical evaluation, physiology and anesthesia
Overall, clinical evaluation is more difficult in an
obese patient compared with a patient in ideal body
condition. Techniques that are complicated by
2006
l
Vol 16 No 1
WALTHAM Focus
21
Clinical risks associated with obesity in companion animals
obesity include physical examination, thoracic
auscultation, palpation and aspiration of peripheral
lymph nodes, abdominal palpation, blood sampling,
cystocentesis, and diagnostic imaging (especially
ultrasonography).
lifespan was also increased (e.g. 13 years with energy
restriction compared with 11.2 years when fed ad lib).
Other beneficial effects included reduced risk of
orthopedic disorders such as osteoarthritis, and
improved glucose tolerance (5,6).
Anesthetic risk is also reportedly increased in obese
companion animals and problems include estimation of
anesthetic dose, catheter placement, and operating time.
Finally, decreased heat tolerance and stamina have also
been reported in obese animals.
Diseases associated with obesity
Endocrine and metabolic diseases
A number of endocrinopathies are associated with
obesity; in some cases obesity is the result of the disorder
whilst, in others, the obesity predisposes to (or
exacerbates) the endocrine disease. Hormonal diseases
with a reported association with obesity include diabetes
mellitus, hypothyroidism, hyperadrenocorticism
(Figure 1), and insulinoma (1). Acromegaly can cause
increased deposition of all soft tissue and is thus a
differential diagnosis for obesity. However, in this
condition, lean tissue and bone mineral are likely to be
deposited in addition to adipose tissue.
Longevity
A recent prospective study has suggested the effect of
obesity on longevity in dogs. Twenty four pairs of
Labrador retrievers (48 total) were used, and one dog in
each pair was randomly assigned to one of two groups
(5). The dogs in one group were fed ad libitum, whilst
the dogs in the other group were fed 75% of the amount
consumed by their respective pair. In the energyrestricted group, body condition score was closer to
‘optimal’ (e.g. group mean 4.5/9 (2.75/5)) than in the
ad lib feeding group (e.g. group mean 6.8/9 (3.8/5));
a.
b.
c.
22
WALTHAM Focus
Table 1.
Diseases associated with obesity
d.
Figure 1.
(a) 11 year-old neutered female crossbred presenting with
hyperadrencorticism. Physical examination revealed poor
coat condition (patches of alopecia and obesity body weight
20 kg, condition score 9/9 (5/5)). (b) Right lateral
abdominal radiograph demonstrating hepatomegaly and
abdominal fat deposition. (c & d) Abdominal ultrasound
confirming hyperplasia of both left (c) and right (d)
adrenal glands. (e) Dual-energy X-ray absorptionometry
(DEXA) demonstrating body fat content of 53%
(reference range 20 to 35%).
Vol 16 No 1
l
2006
Insulin resistance, diabetes mellitus and the metabolic
syndrome
Insulin is secreted by pancreatic ␤-cells and it controls
e.
Metabolic abnormalities
• Hyperlipidemia / dyslipidemia
• Insulin resistance
• Glucose intolerance
• Hepatic lipidosis (cat)
Endocrinopathies
• Hyperadrenocorticism
• Hypothyroidism
• Diabetes mellitus
• Insulinoma
• Hypopituitarism
• Hypothalamic lesions
Orthopedic disorders
• Osteoarthritis
• Humeral condylar fractures
• Cranial cruciate ligament rupture
• Intervertebral disk disease
Cardiorespiratory disease
• Tracheal collapse
• Brachycephalic airway obstruction syndrome
• Laryngeal paralysis
Urogenital system
• Urethral sphincter mechanism incompetence
• Urolithiasis (calcium oxalate)
• Transitional cell carcinoma
• Dystocia
Neoplasia
• Mammary
• Transitional cell carcinoma
Functional alterations
• Joint disorders
• Respiratory compromise e.g. dyspnoea
• Hypertension
• Dystocia
• Exercise intolerance
• Heat intolerance/heat stroke
• Decreased immune functions
• Increased anesthetic risk
• Decreased lifespan
uptake and use of glucose in peripheral tissues. In humans,
tissues become less sensitive to insulin (i.e. become
‘insulin resistant)’ with excessive caloric intake, and
plasma concentrations of insulin increase in direct
proportion to increasing BMI in both men and women.
Thus, obesity, particularly abdominal obesity, is a major
determinant of insulin resistance and hyperinsulinemia.
Cats most often suffer from diabetes mellitus (DM)
resembling ‘type II’ in man, and, similarly, obesity is a
major risk factor in this species (7). Indeed, it has been
experimentally proven that diabetic cats have
significantly reduced sensitivity to insulin than cats
without DM (8). In contrast, dogs more commonly
suffer from DM resembling human type I DM.
Therefore, although obesity is known to cause insulin
resistance, there is no current data proving that obesity is
actually a risk factor for DM in this species. As a result,
obesity alone rarely leads to clinical signs (9).
Hypothyroidism and thyroid function
Although hypothyroidism is commonly cited as an
underlying cause for obesity, such cases are the exception
rather than the rule. The prevalence of hypothyroidism
has been estimated at 0.2%, with under half of these
dogs reported to be obese (10) whereas, in contrast, a
much greater proportion of dogs (17-44%) is known to
be obese (see above). Hypothyroidism is extremely rare
in cats. Thus, whilst hypothyroidism should always be
considered, it is rarely the reason for the obesity in most
cases.
Obesity itself has a subtle, but likely clinically
insignificant, effect on thyroid function (11); obese dogs
were found to have higher concentrations of both total
T4 and total T3 than non-obese controls, although such
concentrations remained within the reference range and
other parameters (e.g. free T4, thyroid stimulating
hormone [cTSH], TSH stimulation test) were not
significantly different. Further, weight loss caused
significant decreases in total T3 and cTSH. Thus,
although obesity and subsequent weight restriction may
have some effects on energy balance and thyroid
homeostasis, such changes are unlikely to affect the
interpretation of thyroid function tests.
Hyperlipidemia and dyslipidemia
There are limited data in dogs with naturally occurring
obesity, and most information has been derived from
experimental studies. Published data suggest that lipid
alterations can occur in obese dogs, with increases in
cholesterol, triglycerides and phospholipids all noted,
albeit often not exceeding the upper limit of the
reference range (12-14). Making laboratory dogs obese
by feeding a hyperenergetic diet has been shown to
increase plasma non-esterified fatty acid and triglyceride
concentrations by increasing concentrations of VLDL
and HDL, whilst decreasing HDL cholesterol (13).
Such changes were associated with insulin resistance
and, interestingly, have also been described in insulinresistant humans. Whether or not lipid alterations
account for the increased incidence of pancreatitis in
obese dogs requires further studies. Thus, further work
will be required to assess further the significance of lipid
abnormalities in dogs.
Orthopedic disorders
Obesity is a major risk factor for orthopedic diseases in
companion animals, especially dogs.
Increased
incidence of both traumatic and degenerative
orthopedic disorders have been reported (Figure 2),
(15). One study reported body weight to be a
predisposing factor in humeral condylar fractures,
cranial cruciate ligament rupture, and intervertebral disc
disease in Cocker Spaniels (16). Further, a number of
b.
a.
c.
d.
Figure 2.
(a) 6 year-old neutered male Labrador with multi-limb lameness and obesity.
On physical examination, the dog was grossly obese (body weight 54.5 kg, body
condition score 5/5. (b) Lateral radiograph of the left elbow radiograph
demonstrating osteoarthritis. (c) Ventrodorsal radiograph of the pelvis,
demonstrating osteoarthritis of both hips, secondary to hip dysplasia.
(d) DEXA prior to weight loss confirming body fat content of 42%
(reference range 20 to 35%).
2006
l
Vol 16 No 1
WALTHAM Focus
23
studies have highlighted the association between obesity
and the development of osteoarthritis (6, 17), whilst
weight reduction can lead to a substantial improvement
in degree of lameness in dogs with hip osteoarthritis
(Figure 2), (18).
Cardiorespiratory disease and hypertension
Obesity can have a profound effect on the function of
the respiratory system (for example, see WSAVA
abstract). Most notably, obesity is an important risk
factor for development of tracheal collapse in small dogs
(19). Obesity can exacerbate heatstroke in dogs, whilst
other respiratory diseases that can be exacerbated by
obesity include laryngeal paralysis and brachycephalic
airway obstruction syndrome.
Obesity can also affect cardiac function; increased body
weight can result in effects on cardiac rhythm, increase
left ventricular volume, blood pressure and plasma
volume. The effect of obesity on hypertension is
controversial in the dog. One study suggested that
obesity was significantly associated with hypertension,
but its effect was only minor (20). In contrast, many
experimental studies have utilized the obese dog as a
model for the pathogenesis of hypertension and insulin
resistance (21). Obesity may also be associated with
portal vein thrombosis, and myocardial hypoxia.
Urinary tract and reproductive disorders
An association between obesity and some cases of
urethral sphincter mechanism incompetence (USMI)
has been reported (22). Obesity is not the only risk
factor, with overiohysterectomy itself also playing a
major part. Nevertheless, the effect of obesity is clear in
some dogs, which only become incontinent when they
become obese. Conversely, weight reduction in
overweight dogs with USMI can often be all that is
required to allow continence to be restored. The reason
for an association between USMI and obesity is not
clear, although the effect may be purely mechanical e.g.
increased retroperitoneal fat leading to caudal
displacement of the bladder. The risk of developing
calcium oxalate urolithiasis is also reported to be
increased in obese dogs (23), whilst other urinary tract
disorders may be exacerbated by obesity.
Obese animals are reported to suffer from increased risk
of dystocia, likely related to excess adipose tissue in and
around the birth canal (15).
24
WALTHAM Focus
Vol 16 No 1
l
2006
Neoplasia
In humans, obesity is known to predispose to a number
of different types of cancer; the International Agency for
Research on Cancer has found there to be a significant
link between obesity and cancers of the female breast
(postmenopausal), colon/rectum, kidney (renal cell) and
esophagus. It is estimated that if this link is entirely
causal, being overweight or obese may account for one
in seven cancer deaths in both men and women in the
USA alone.
Breast cancer is the most common form of cancer among
women worldwide. Obesity has consistently shown to
increase rates of breast cancer in postmenopausal women
by 30-50%. An association between mammary
carcinoma and obesity has also been reported in some but
not all canine reports. Overweight dogs have also
reported to have an increased risk of developing
transitional cell carcinoma of the bladder (24). However,
a possible link between obesity and other companion
animal cancers has not been explored fully.
Miscellaneous disorders
Obese animals have been reported to be at increased risk of
certain dermatologic disorders. Diffuse scale is commonly
observed (especially in cats), most likely due to reduced
ability to groom efficiently. Animals that are severely obese
can develop pressure sores (Figure 3). Decreased immune
a.
b.
c.
d.
Figure 3.
(a and b) 9 year old neutered male Siamese cat with gross obesity (body weight
12.95 kg, condition score 9/9 (5/5)). The obesity had led to inactivity, inability to
groom and pressure sores on the ventral abdomen (c). (d) DEXA prior to weight loss
confirmed body fat content of 54.4% (reference range 18 to 25%).
function has also been documented, with obese dogs being
less resistant to the development of infections.
Adipokines
Adipokines are critical in the development of many
obesity-associated disorders. The presence of excessive
white adipose tissue (WAT) in obesity can predispose to
the numerous disorders discussed above through a
number of possible mechanisms. First, deposition of
excessive fat can have ‘mechanical’ or ‘physical’ effects
e.g. excessive weight bearing exacerbating orthopedic
diseases, constriction of upper airways exacerbating
respiratory disorders, inability to groom in
dermatological complaints, and reduced heat dissipation
due to the insulating effect of fat for heat stroke.
However, the perturbation of the normal endocrine
function of WAT is now recognized as a major
pathogenetic mechanism for the development and
exacerbation of many of the obesity-associated disorders.
Traditionally, WAT was thought of as a ‘passive’ organ,
with few functions other than energy storage and
insulation. However, more recently, WAT has been
shown to be an active endocrine organ, secreting
numerous factors, which can have a regulatory effect on
many body systems. The endocrine functions of WAT
are key to a number of normal physiological processes
and, when WAT is present in excessive amounts in obese
individuals, these normal processes can become
disrupted.
The term ‘adipokine’ refers to a protein which is secreted
from the adipocytes of WAT (25); some such factors
have proven endocrine roles (e.g. leptin and
adiponectin), whilst other may have autocrine and
paracrine effects on adipose tissue itself (e.g. tumor
necrosis factor alpha [TNF-␣] and interleukin 6 [IL-6]).
The adipokines include angiogenic factors (e.g. vascular
endothelial growth factor), cytokines (e.g. IL-6), acute
phase proteins (e.g. haptoglobin) and proteins involved
in vascular hemostasis (e.g. plasminogen activator
inhibitor-1; PAI-1), blood pressure regulation (e.g. angiotensinogen), the alternative complement system (e.g.
adipsin) and lipid metabolism (e.g. cholesteryl ester
transfer protein) (25, 26).
The diversity of the adipokines implies that WAT is
widely involved in metabolic regulation, involving
extensive communication with other organs. Increases
in the production of several adipokines have been
documented in human obesity, including leptin, TNF-␣,
IL-6, PAI-1 and haptoglobin (25, 26). The production
of adiponectin, on the other hand, is decreased in the
obese (27). Such changes in adipokine secretion in
obesity may be causally related to the development of
the metabolic syndrome and other disorders linked to
the obese state.
Adipokines and insulin resistance
Circulating levels of several adipokines, such as
haptoglobin and TNF-␣, have been found to be raised
in both diabetes mellitus and obesity (28).
Adipokines, obesity and inflammation
It has become generally accepted that obesity is associated
with a state of chronic low-grade inflammation, and that
this inflammatory state may be the link between obesity,
DDMII and cardiovascular disease (25). In these states
several markers of inflammation including acute phase
proteins and cytokines such as TNF-␣ and IL-6, mainly
thought to be of adipose tissue origin, are found to be
elevated (25). The precise site of the inflammatory process,
whether systemic or local, is still a matter of debate.
Adipokines and hypertension
White adipocytes are thought to be an important source
of angiotensinogen (26), the substrate for renin in the
renin-angiotensin aldosterone system (RAAS). This
suggests that WAT plays an important role in blood
pressure regulation. Indeed, it appears that apart from
the liver, WAT may be the most important source of
angiotensinogen (26). Importantly, circulating levels of
angiotensinogen have been found to be raised in obesity.
This suggests a direct link between hypertension and
obesity (26).
Adipokines and thrombosis
Plasminogen activator inhibitor-1 (PAI-1) is important
in the maintenance of vascular hemostasis, where it
functions by inhibiting the activation of plasminogen,
the precursor of plasmin, which is involved in the
breakdown of fibrin (25). The expression and secretion
of PAI-1 in both human and rodent adipocytes has been
well documented (25). Visceral adipocytes are thought
to be the main source of PAI-1,(29) indicating a strong
link between visceral adiposity, PAI-1 levels and the
increased incidence of atherothrombotic disorders
frequently associated with visceral obesity.
Summary
Obesity is a growing concern in companion animals, and
the increasing incidence appears to be mirroring the trend
seen in humans. The main medical concern of obesity
relates to the many diseases associations that accompany
2006
l
Vol 16 No 1
WALTHAM Focus
25
adiposity. Adipokines are thought to play a part in the
pathogenesis of many obesity-associated disorders in man,
and there are likely to be many parallels with companion
animal disorders. There is a need both to increase the
awareness of companion animal obesity as a serious
medical concern within the veterinary profession, and to
investigate more closely the pathogenetic basis of the
various diseases associated with obesity.
Acknowledgements
The author would like to thank Viv Ryan and Shelley
Holden for assistance with manuscript preparation, and
Royal Canin for lectureship funding at the University of
Liverpool. u
references
1. Burkholder WJ, Toll PW. Obesity In: MS Hand, CD Thatcher, RL
Reimillard, P Roudebush, ML Morris, BJ Novotny, eds; Small Animal Clinical
Nutrition, 4th ed. Mark Morris Institute, Topega, Ka, USA. 2000; pp 401-430.
2. McGreevy PD, Thomson PC, Pride A, et al. Prevalence of obesity in dogs
examined by Australian veterinary practices and the risk factors involved. Vet
Rec 2005; 156: 695-707.
3. Doria-Rose VP, Scarlett JM. Mortality rates and causes of death among
emaciated cats. J Am Vet Med Assoc 2000; 216: 347-351.
4. Scarlett JM, Donoghue S. Associations between body condition and disease
in cats. J Am Vet Med Assoc 1998; 212: 1725-1731.
5. Kealy RD, Lawler DF, Ballam JM, et al. Effects of diet restriction on life
span and age-related changes in dogs. J Am Vet Med Assoc 2002; 220: 13151320.
6. Kealy RD, Lawler DF, Ballam JM, et al. Evaluation of the effect of limited
food consumption on radiographic evidence of osteoarthritis in dogs. J Am Vet
Med Assoc 2000; 217: 1678-1680.
7. Nelson, RW, Himsel CA, Feldman EC, et al. Glucose tolerance and insulin
response in normal weight and obese cats. Am J Vet Res 1990; 51: 1357-1362.
8. Feldhahn JR, Rand JS, Martin G. Insulin sensitivity in normal and diabetic
cats. J Fel Med Surg 1999; 1: 107-115.
9. Rand JS, Fleeman LM, Farrow HA. Canine and feline diabetes mellitus:
nature or nurture? J Nutr 2004; 134: 2072S-2080S.
10. Scott-Moncrief JCR, Guptill-Yoran L. Hypothyroidism. In: SJ Ettinger
and EC Feldman (eds) Textbook of Veterinary Internal Medicine, 5th edition.
WB Saunders Co, Philadelphia, PA, USA 2000; 1419-1428.
11. Daminet S, Jeusette I, Duchateau L, et al. Evaluation of thyroid function
in obese dogs and in dogs undergoing a weight loss protocol. J Vet Med Assoc
2003; 50: 213-218.
12. Chikamune T, Katamoto H, Ohashi F, et al. Serum lipid and lipoprotein
concentrations in obese dogs. J Vet Med Assoc 1995; 57: 595-598.
13. Bailhache E, Ouguerram K, Gayet C, et al. An insulin-resistant
hypertriglyceridaemic normotensive obese dog model: assessment of insulin
resistance by the euglycaemic hyperinsulinaemic clamp in combination with
the stable isotope technique. J Anim Physiol Anim Nutr 2003; 87: 86-95.
14. Diez M, Michaux C, Jeusette I, et al. Evolution of blood parameters
during weight loss in experimental obese Beagle dogs. J Anim Physiol Anim
Nutr 2004; 88: 166-171.
15. Edney ATB, Smith PM. Study of obesity in dogs visiting veterinary
26
WALTHAM Focus
Vol 16 No 1
l
2006
practices in the United Kingdom. Vet Rec 1986; 118: 391-396.
16. Brown DC, Conzemius MG, Shofer FS. Body weight as a predisposing
factor for humeral condylar fractures, cranial cruciate rupture and
intervertebral disc disease in Cocker Spaniels. Vet Comp Orth 1996; 9: 75-78.
17. Kealy RD, Lawler DF, Ballam JM, et al. Five-year longitudinal study on
limited food consumption and development of osteoarthritis in coxofemoral
joints of dogs. J Am Vet Med Assoc 1997; 210: 222-225.
18. Impellizeri JA, Tetrick MA, Muir P. Effect of weight reduction on clinical
signs of lameness in dogs with hip osteoarthritis. J Am Vet Med Assoc 2000;
216: 1089-1091.
19. White RAS, Williams JM. Tracheal collapse in the dog – is there really a
role for surgery? A survey of 100 cases. J Small Anim Pract 1994; 35: 191-196.
20. Bodey AR, Mitchell AR. Epidemiological study of blood pressure in
domestic dogs. J Small Anim Pract 1996; 37: 116-125.
21. Truett AA, Borne AT, Monteiro MP, et al. Composition of dietary fat
affects blood pressure and insulin responses to dietary obesity in the dog.
Obesity Res 1998; 6: 137-146.
22. Gregory SP. Developments in the understanding of the pathophysiology of
urethral sphincter mechanism incompetence in the bitch. Br Vet J 1994; 150:
135-50.
23. Lekcharoensuk C, Lulich JP, Osborne CA, et al. Patient and
environmental factors associated with calcium oxalate urolithiasis in dogs.
J Am Vet Med Assoc 2000; 217: 515-519.
24. Glickman LT, Schofer FS, McKee LJ, et al. Epidemiologic study of
insectoside exposure, obesity, risk of bladder cancer in household dogs.
J Toxicol Environ Health 1989; 28: 407-414.
25. Trayhurn P, Wood IS. Adipokines: inflammation and the pleiotropic role
of white adipose tissue. Br J Nutr 2004; 92: 347-355.
26. Trayhurn P, Beattie JH. Physiological role of adipose tissue: white adipose
tissue as an endocrine and secretory organ. Proc Nutr Soc 2001; 60: 329-339.
27. Arita Y, Kihara S, Ouchi N, et al. Paradoxical decrease of an adiposespecific protein, adiponectin, in obesity. Biochem Biophys Res Commun 1999;
257: 79-83.
28. Hotamisligil GS. Inflammatory pathways and insulin action. Int J Obes
Relat Metab Disord 2003; 27 Suppl 3: S53-55.
29. Guerre-Millo M. Adipose tissue and adipokines: for better or worse.
Diabetes Metab 2004; 30: 13-19.
Management of Satiety
Robert C. Backus, MS, DVM, PhD, Dip ACVN
Director of the Small Animal Nutrition Program, Department of Veterinary Medicine and Surgery, Clydesdale
Hall, 379 E. Campus Drive, University of Missouri-Columbia, Columbia, MO 65211 USA
Robert C. Backus graduated from the University of California-Davis, School of Veterinary Medicine in 1987 and was
awarded MS and PhD degrees in Physiology in 1987 and 1991, respectively. While at Davis, Robert began his study
of small animal nutrition as a Waltham Fellow investigating causes of taurine deficiency in cats. Later, his research
interests broadened and he became a research faculty member and then Director of the Feline Nutrition and Pet Care
Center at Davis. In 2004, Robert Backus received Board certification with the American College of Veterinary Nutrition and relocated
to the University of Missouri to initiate a clinical and basic science program in small animal nutrition.
His present research interests are protein nutrition and metabolism and energy balance regulation and related disease.
KEY POINTS
Introduction
When one encounters a conspicuously obese cat, it
is perhaps a common reaction to blame gluttony
and envision the cat flailing away in a pan of
lasagna, a dish known as “nature’s perfect food” to
Jim Davis’ Garfield the comic-strip cat. Once past
this initial reaction, some of us ponder the
disturbance that led to the obesity we observe.
Indeed, overeating appears to be the culprit in many
cases, an example of which being the weight gain
and in some cases obesity following neutering (1)
(Figure 1).
However, diminished energy expenditure in the face
of constant food intake also may cause undesired
weight gain. This has been observed in spayed
female cats when food intake is controlled to prespay levels (2). Decades of research on humans and
animal models have led to the synthesis of many
theories on the origin of obesity. Weakened satiety
and enhanced feelings of hunger are perhaps the
most intuitively obvious of causes for obesity.
Orchiectomized
n=8
Body weight (g)
Á The origin of obesity that we observe in dogs and cats
is not well understood. This lack of understanding
occurs in spite of reports that as many as 50 % of
dogs and cats are overweight in middle age
Á The overeating that we observe in dogs and cats
probably has many causes and the variation in the
degree of obesity that we observe may well reflect
differences in cause for overeating
Á Although it might seem logical to prevent overeating
by the management of factors that influence hunger,
satiation, and satiety, it should be noted that
disturbed satiation and satiety can lead to obesity,
and obesity influences satiation and satiety in a
manner that supports obesity
Á Agents that induce satiety may be one of several targets
for which prospective medications may be developed.
Other targets include anorectics, fat absorption
inhibitors, thermogenics, and agents that partition
energy away from adipose toward muscle
Á Perhaps the best way to manage satiety in the long
run is to manage influential factors like obesity rather
than to evoke extraordinary stimulation of satiety
signals. By this way of thinking, weight loss should
be undertaken first in the treatment of obesity
Intact
n=8
Time (day)
Figure 1.
Body weight gain observed in adult male cats before and after orchiectomy.
All cats were continuously presented with a dry-type commercial diet for ad lib
consumption, except for a food withholding during the day of orchiectomy (indicated by
the vertical broken line). Mean ± SE bodyweight loss caused by food restriction from 24
to 48 hours in male cats. The green box marks the period of food intake observations for
the cats shown in Figure 5.
2006
l
Vol 16 No 1
WALTHAM Focus
27
Other causes are more abstract and for humans are
described categorically as sensorily-induced overconsumption, hedonistically-mediated maladaptive food
choices, and errors in processes governing energy balance
(3). The later cause of energy balance errors may be
applicable to some breeds of dogs that are especially
prone to obesity.
While causal theories abound, much to our disappointment, the origin of obesity that we observe in dogs
and cats is not well understood. This lack of
understanding occurs in spite of reports that as many as
50 % of dogs and cats are overweight in middle age (4, 5).
Overeating
Past investigators have importantly noted that obesity
occurs when palatable food is available in excess, and
hard physical activity is not required. These conditions
are becoming increasingly prevalent in the global
population of humans, and they are likely experienced
by their dog and cat companions. Given the recent
global trend, it is not difficult to find grounds to
speculate that obesity in companion animals results from
a poor control of food intake in an environment of food
abundance. In the case of cats, making food abundantly
available is easy and commonly practiced with feeding of
commercial dry-type (extruded) diets. Dry diets are
often continuously presented whereas moist foods, such
as the less energy dense commercial canned diets, are
more often given intermittently.
At least in the United States, it is the commercial drytype diets that appear most frequently consumed by
obese cats (6). Reducing the availability of food by
limiting exposure to diets reduces the risk for obesity (5)
Intact n=8
Orchiectomized n=8
Body weight (g)
Begin 4 hr/day food restriction
Day relative to restriction
Figure 2.
Body weight loss caused by restriction of food presentation from 24 to 4 hours per day in male
cats of healthy body condition and male cats previously made overweight by orchiectomy
(adapted from reference 7). The plotted values are means and associated error bars represent
standard error of the mean. The food presented was a dry-type commercial diet.
28
WALTHAM Focus
Vol 16 No 1
l
2006
and effectively reduces body weight in obese cats (7)
(Figure 2). In the case of dogs, more so than cats,
continuous presentation of food rapidly leads to
undesired weight gain. Temporal restriction of food as
used in cats is not very effective in preventing obesity in
dogs. As many dog owners can attest, dogs may
consume their daily caloric needs in a very short time
and then demonstrate poor food intake control with
continued begging or display of other food seeking
behavior.
Curiously, not all animals become obese when food is
continuously present. It has been suggested that this
heterogeneity reflects individual variation in elements
contributing to the control of food intake, where the
individual variation is not apparent until food is available
in excess. The inquisitive among us may wonder about
mechanisms underlying individual adiposity differences,
and some of us may believe that understanding them will
aid in the prevention and treatment of obesity.
Unfortunately, complete understanding of why some
animals overeat while others do not appears far-off. Over
six decades of scientific investigation has revealed that the
control of food intake is a complex process, comprised of
many central and peripheral elements that are highly
integrated and in some cases redundant in function. The
central component, which is believed to be seat of the drive
to eat (and probably overeat), is now seen as a composite of
diffusely organized neuronal circuits spanning many brain
regions. This view contrasts substantially with the once
proposed food intake control model of anatomically
distinct, hypothalamic centers that determine hunger and
satiety. The structural and functional complexity now
recognized in the control of food intake presents many
possible sites where disturbances might act to cause
overeating. Hence, the overeating that we observe in dogs
and cats probably has many causes. The variation in the
degree of obesity that we observe may well reflect
differences in cause for overeating.
Satiation and satiety
For the purpose of presenting strategies to prevent
overeating in cats and dogs, it is useful to consider food
intake as a behavior rather than an outcome of a
complex, incompletely understood physiological process.
In this way, food intake can be described in terms as the
amount of energy consumed, dietary pattern, or
macronutrient profile. An example of this approach are
studies of Kane and others (8) on feeding patterns in cats.
When food in the form of a commercial dry-type diet is
made continuously available, cats are found to eat many
small meals each day (0 = 11 to 12), with a slight diurnal
pattern of more meals in light than in dark periods.
When considering food intake as a behavior, one might
infer that there are unique motivations behind the
behavior. Animals probably have counterparts to the
motivations experienced by humans that compel them
to eat or not to eat. Hunger is a key motivation in
human models of food intake. Hunger is defined as a
biological drive impelling ingestion of food, and in
humans, it is described as a distinct sensation. Hunger
varies in strength, and its strength importantly
determines when and how much to eat. With ingestion
of food, hunger diminishes, and physiological processes
that inhibit food intake are stimulated. With continued
eating, a feeling of fullness develops so that eventually
eating is terminated. Eating will not resume until the
feeling of being full subsides, and hunger again develops.
The increasing sensation of fullness developing during a
meal is called “satiation”. Those who study food intake
behavior distinguish satiation from satiety. Satiety is
considered a motivation not to eat between episodes of
eating. It is the state of satiety that delays the onset of a
meal and may reduce the amount of food consumed in a
forthcoming meal. Here, it is instructive to cite that
“satiation” and “satiety” are defined by some
investigators as intra- and inter-meal satiety, respectively.
In Figure 3, the timing of hunger and satiety in relation to
food intake is illustrated against the meal-pattern
observations in a cat by Kane and others (8). When
considering this model, it is natural to speculate that
overeating (expressed as increased meal size and or meal
frequency) is caused by increased hunger, diminished
satiation, or reduced satiety. In view of this model, a logical
approach to prevention of overeating is management of
factors that influence hunger, satiation, and satiety. Of such
influential factors, diet and environment are well within the
control of those who care for dogs and cats.
Blundell (3) has proposed that characteristics of food
and physiological responses to the characteristics interact
and determine the duration and strength of satiation
and satiety (Figure 4). In this view, responses to food
are categorized as sensory, cognitive, post-ingestive, and
post-absorptive. Food characteristics that serve as
stimuli include volume, weight, energy content, energy
density, and macronutrient proportion. Although
developed for humans, Blundell’s model appears suitable
for evaluating factors important for the management of
satiety in dogs and cats. Perhaps a good factor to first
consider in this model is dietary fat. For cats, when the
weight percentage of fat in a purified diet is increased
from 15 to 45 % (4.8 to 6.2 kcal/g, respectively), meal
size decreases while meal frequency is not significantly
changed (Figure 5). Meal size in this case decreases to
Hunger
Satiety
TIME (hr)
dark
light
Figure 3.
Probable timing of hunger, satiation, and satiety in relation to meals consumed by a cat
continuously presented with food (adapted from references 3 and 8). Meal size is indicated by the
area of the meal plot where rate of food intake during each meal was assumed to be similar. The
letter ‘S’ label indicates the approximate time of meal termination when the cat would be satiated.
Mediating-integrating processes
Post-absorptive
Post-ingestive
Cognitive
Sensory
Early
Food
Late
Satiety
Satiation
Figure 4.
A model illustrating the functional and temporal relationship among sensor, integrator, and
effector elements of satiation and satiety in cats and dogs. Adapted from the “satiety cascade”
proposed by Blundell (3) to explain characteristics of satiation and satiety in humans.
15% fat
45% fat
light
TIME (hr)
dark
Figure 5.
Decrease in meal size but not frequency observed in cats that occurs in response to an increase in
dietary fat (adapted from reference 8). In this case, the decrease is appropriate for maintenance
of body weight. Meal size is indicated by the area of the meal plot where rate of food intake
during each meal was assumed to be similar.
the extent that energy intake is not significantly affected.
It may be that sensitivity to sensory input important in
satiation increases to the extent that a body energy
imbalance does not occur. A heightened sensitivity to
the volume and weight of the high-fat diet might have
developed as a conditioned response. On the other
hand, if meal frequency were found to be decreased in
cats given the high-fat diet, then it might be suggested
that sensitivity to post-ingestive and pre-absorptive
inputs are increased, and satiety is appropriately
prolonged. Unfortunately, this response of cats to a
high-fat purified diet does not seem to be congruous
with what is typically observed for commercial diets.
2006
l
Vol 16 No 1
WALTHAM Focus
29
Anecdotal accounts and an epidemiological study
indicate that increasing fat in commercial dry-type diets
increases the risk of obesity (6).
especially palatable to cats and to some other species,
increasing its concentration in a diet is found to reduce
food intake (12).
In considering Blundell’s model, many causes for a
varying effect of fat on food intake can be offered. For
example, the sensory response to the greater palatability
of a commercial relative to a purified diet may prolong
the satiation phase. Unfortunately, effects of dietary
factors on meal patterns in cats and dogs appear to be
rarely reported. Future study of how dietary fat affects
meal patterns in cats given commercial dry-type diets
may be useful in sorting out fat’s effect on satiation and
satiety. If a dietary factor is found to attenuate satiation,
then overeating might be best prevented by control of
food portions. Whereas, if a dietary factor is found to
reduce satiety, then decreasing the period of dietary
exposure might be more convenient than portion
control for preventing overeating.
Most studies show that dietary fat has a weaker effect on
satiation and satiety than dietary carbohydrate (10). For
many species, increasing the concentration of dietary fat
results in an increase in the amount of adipose mass
maintained. The weak satiating potency of dietary fat is
consistent with this observation.
Relative to
carbohydrate, absorption and metabolism is slower with
fat. The delay in sensing a fat load may attenuate fat’s
satiation potency and more easily permit overconsumption of calories from fat than carbohydrate.
Slight over-consumption of fat may further weaken
satiating potency of dietary fat if body fat mass is
expanded. This effect of dietary fat is indicated in a
recent study of brain insulin transport in dogs made
obese by feeding a high-fat diet (13). While insulin is
well known for its role in metabolism, insulin also
negatively feeds back on food intake. With obesity,
insulin transport to the brain is impaired. A not so
surprising application of these findings is that feeding of
diets high in fat should be avoided for management of
satiety. An interesting enigma worthy of note is that
feline commercial canned diets are typically high in fat,
but obesity is not typically associated with canned diet
feeding. One explanation for this paradox is that the
palatability of canned diets rapidly diminishes with
exposure to ambient conditions, and therefore meal
frequency may be unintentionally reduced. Another
explanation is that overeating may be precluded by the
large caloric dilution with water in canned diets.
Dietary macronutrients
It is pertinent to point out that dietary components
differently engage processes mediating satiation and
satiety. Dietary protein is generally believed to exert a
potent effect on satiety (10). Relative to protein, dietary
carbohydrate and fat are less inhibitory of food intake,
and between carbohydrate and fat, fat appears to be the
least potent in affecting food intake. The basis of
protein’s potency is unknown. Its effect appears to occur
above dietary protein requirement levels, a condition
that would seem consistent with a regulation of dietary
protein intake (11). Some essential amino acids when
ingested in excess of their requirement are believed to
produce physiological stress in proportion to their
toxicity. As physiological stress is known to alter feeding
behavior, herein may be a mechanism for the increasing
inhibition of food intake with increasing dietary protein.
Cats appear to deviate from other species in their
susceptibility to protein’s potent effect on satiety.
Purified diet studies show that cats do not have a strong
metabolic cue to consume a particular “optimal” level of
protein (12). A diet as high as 63 % (wt/wt) in soyprotein is consumed in amounts similar to a diet
containing moderate (31 %) and near-requirement
levels (16 %) of protein. Cats may not even discriminate
against eating a diet lacking in protein when given an
equally palatable diet that contains protein. This
uniqueness of cats would appear to preclude using
dietary protein concentration as a means to manage
satiety in cats. However, it is important to note that
dietary protein sources vary in their palatabilities. A
relevant example is casein. Because casein is not
30
WALTHAM Focus
Vol 16 No 1
l
2006
While satiety has a clear definition as applied by
behaviorist, its definition is not as clear in all
applications. Physiological responses to food that
contribute to meal-termination or those that facilitate
further inhibition of food intake are called “satiety
signals”. Such signals could exert their effect by
decreasing the drive to eat (hunger) or increasing the
feeling of being full during or between meals (satiation
and satiety, respectively). Overriding satiety signals that
arise from the volume of food consumed (e. g., from
gastric distension) may explain the obesity resistance
found with feeding high-moisture, canned diets to cats.
Diets made high enough in metabolically inert material
such as water and some dietary fibers might protect
against overeating by a common means. In the case of
fiber, effects on satiation and satiety in dogs and cats
have not been well described. High fiber diet
presentation for ad libitum consumption reportedly can
promote weight loss in dogs (14) and cats (15).
Transient potency of satiety signals
Another point to consider with dietary fiber and other
interventions used to manage satiety is the redundancy
of feedback inputs in food intake control. There are
many satiety signals and each provides information on
one or more attributes of food. A particular satiety
signal may lose its potency in suppressing food intake
when its importance to energy balance is learned to be
inconsequential. Such learning about satiety signals is
apparent in the ability of an animal to appropriately
decrease or increase their food intake with a changing
energy density of food. Therefore, in some cases, effects
of a dietary manipulation on satiation and satiety may be
fleeting, and in the long run they might not prevent the
overeating that leads to undesired weight gain.
When presented with a variety of foods, there is a welldescribed tendency for animals to consume more than
just their preferred food (17). This behavior is believed
to be resultant of satiety being specific to sensory
properties of a food being ingested, such as, taste, odor,
and texture. When given a choice of foods, an initially
preferred food may become less appealing while a lesser
preferred food becomes increasingly attractive. A
consequence of this phenomenon is that food intake is
enhanced (and probably inappropriately) by increasing
the types of foods made available for consumption.
Such “sensory-specific satiety” may in part explain why
obesity is associated with the feeding of treats, which
often varying their sensory properties. Therefore, for the
purpose of managing satiety, food variety should be
limited and treats might best provided as portions of the
maintenance diet.
Non-dietary manipulations
Control of food intake is interconnected with several
other biological systems. This integration is a means by
which factors unintuitively related to food intake
influence satiation and satiety. An example is the
increase in meal size typically observed in animals
previously deprived of food. Satiation in this case is
influenced by the state of energy balance. In human
obesity, meal size rather than meal frequency is greater
than it should be for maintenance of a healthy body
condition. Hence, in obesity, satiation appears altered so
that an abnormally large adipose mass is defended. A
similar condition probably occurs in dogs because food
presentation in most obese dogs is controlled (albeit
insufficiently), thereby eliminating the variable of meal
frequency. However, this condition is not a certainty
because obese dogs often receive treats throughout the
day, and their interest in treats may reflect diminished
satiety. To my knowledge, it has not been reported
whether obese relative to lean cats have larger meals or
more frequently visit the food bowl. In any case,
satiation and satiety appear negatively influenced by
obesity in companion animals (e. g., the food intake
differences found between overweight neutered and lean
intact cats, Figure 6). This influence of obesity presents
a uniquely difficult problem to solve. Disturbed
satiation and satiety can lead to obesity, and obesity
influences satiation and satiety in a manner that
supports obesity. Perhaps the best way to manage satiety
in the long run is to manage influential factors like
obesity rather than to evoke extraordinary stimulation of
satiety signals. By this way of thinking, weight loss
should be undertaken first in the treatment of obesity.
Then, once body weight is normalized, future weight
gain may be prevented by measures increasing satiation
and satiety, such as, feeding diets low in calories, low in
fat and or high in protein
Early studies of food intake control brought to light that
many areas of the brain may influence food intake in
dogs and cats (18). Facilitation and inhibition of feeding
by the limbic system are especially important findings of
this early work. Buffington (19) recently has suggested
that obesity risk is in part determined by how an animal
reacts to its environment. His thesis, which is developed
Orchiectomized
n=8
Energy intake (kJ/kg 3/4)
However, some investigators find no specific satiety
value of dietary fiber in energy restricted dogs given
calorically dilute (~ 0.5 kcal/gram of feed), high
moisture (> 80 %) diets (16). Future study might
demonstrate significant satiation and satiety benefits
from dietary fiber. However, it may not be useful
because of secondary problems of constipation,
unacceptable excessive fecal output, and decreased
palatability and nutrient digestibilities.
O
r
c
h
i
e
c
t
o
m
y
Intact
n=8
Time (day)
Figure 6.
Metabolizable energy intake of adult male cats before and after orchiectomy
(from 1). The plotted values represent means determined from food intakes and
metabolizable energy equivalence of the diet. The stair-step increase in energy
intake after orchiectomy was an apparent compensatory over-consumption from
food being withheld from all cats for one day (indicated by the black box).
2006
l
Vol 16 No 1
WALTHAM Focus
31
for cats, is based on observations of high obesity risk for
animals that are inactive and living indoors – suggested
unnatural and stressful conditions to some animals.
How environmental variables (of which there are many)
might affect satiation and satiety in companion animals
has not been described. Manipulation of environmental
variables to reduce stress that is done in treatments of
many chronic diseases may be beneficial for satiety
management. Suggested effective measures are changes
in feeding practices, available space, opportunities for
play, environment enrichment, and interactions with
humans and other animals (19).
The current treatment of choice for obesity in dogs and
cats is food restriction with manipulations to increase
physical activity. This treatment often fails because of
poor owner compliance in the face of displays of hunger
and or weakened satiety. The lacking success of obesity
treatment has spawned interest in pharmaceutical
solutions. Unfortunately, little data are available on
pharmacological approaches to obesity in companion
animals (20). Past pharmacotherapies generally have
been unsuitable for humans and companion animals
because of significant side effects and poor risk-benefit
ratios. Recent rapid expansion in knowledge of food
intake control has given rise to speculation that effective
and safe pharmacological treatments of obesity may be
realized in the future. Agents that induce satiety may be
one of several targets for which prospective medications
may be developed. Other targets include anorectics, fat
absorption inhibitors, thermogenics, and agents that
partition energy away from adipose toward muscle.
Future satiety inducers could be satiety signal mimics or
agonists and antagonists of receptors in satiety pathways,
such as those involving cholecystokinin (CCK),
glucagon-like peptide (GLP-1), ghrelin, and peptide YY
(PYY). It should be appreciated that potential human
applications drive research for obesity pharmaceuticals.
While progress may occur here, corresponding applications
for dogs and cats should not be assumed. Less effectiveness
and side-effects that are more severe or unique are reported
in dogs and cats for agents developed for humans.
Conclusions
Because obesity appears to sustain the drive to overeat,
satiety management is probably best used for prevention
rather than treatment of obesity. Measures, which
enhance satiety, are the feeding of diets low in fat and
low in energy density, where energy density may be
decreased by caloric dilution with water or fiber. Diets
containing protein in excess of concentrations needed to
meet an animal’s requirement for protein may be useful
for managing satiety in dogs, but not cats.
Whether by dietary or pharmacological means,
exploitation of satiety signals to enhance satiation or
satiety may be effective only transiently. This is because
“learning” occurs in the control of the food intake. The
satiation potency of food characteristics such as volume,
weight, taste, and texture is not static but dynamic.
Little is reported about how meal patterns in dogs and
cats are affected by dietary and environmental factors.
Future research may reveal that satiation and satiety can
be beneficially manipulated to prevent overeating with
safe and effective pharmacological agents or environmental
changes that reduce stress. u
references
1. Kanchuk M, Backus R, et al. Weight gain in gonadectomized normal and
lipoprotein lipase-deficient male domestic cats results from increased food
intake and not decreased energy expenditure. J Nutr 2003; 133: 1866-1874.
2. Flynn M, Hardie M, et al. Effect of ovariohysterectomy on maintenance
energy requirement in cats. J Am Vet Med Assoc 1996; 209: 1572-1581.
3. Blundell J and Stubbs J. Diet composition and the control of food intake
in humans. In: Handbook of Obesity, Etiology and Pathophysiology, 2nd ed.
Bray G and Bouchard C, eds. Marcel Dekker, New York. 2004. Pp. 427-460.
4. Armstrong J and Lund E. Changes in body composition and energy
balance with aging. Vet Clin Nutr 1996; 3: 83-87.
5. Russell K, Sabin R, et al. Influence of feeding regimen on body condition
in the cat. J Small Anim Pract 2000; 41: 12-17.
6. Scarlett J and Donoghue S. Obesity in cats: prevalence and prognosis.
Vet Clin Nutr 1997; 3: 22-26.
7. Backus R, Kanchuk M, et al. Elevation of plasma cholecystokinin
concentration following a meal is increased by gonadectomy in male cats.
J Anim Nutr Physiol 2005; (in press).
8. Kane E, Leung P, et al. Diurnal feeding and drinking patterns of adult cats
as affected by changes in the level of fat in the diet. Appetite 1987; 9: 89-98.
9. American Veterinary Medical Association (AVMA). The ‘CatKins’ diet, the
feline diet: a historical look. In: 140th AVMA Annual Convention Daily
News, July 22, 2003.
10. Gerstein D, Woodward-Lopez G, et al. Clarifying concepts about macronutrients'
32
WALTHAM Focus
Vol 16 No 1
l
2006
effects on satiation and satiety. J Am Diet Assoc 2004; 104: 1151-1153.
11. Tôrres C, Hickenbottom S, et al. Palatability affects the percentage of
metabolizable energy as protein selected by adult beagles. J Nutr 2003; 133:
3516-3522.
12. Cook N, Kane E, et al. Self-selection of dietary casein and soy-protein by
the cat. Physiol Behavior 1985; 34: 583-594.
13. Kaiyala K, Prigeon R, et al. Obesity induced by a high-fat diet is
associated with reduced brain insulin transport in dogs. Diabetes 2000; 49:
1525-1533.
14. Borne A, Wolfsheimer K, et al. Differential metabolic effects of energy
restriction in dogs using diets varying in fat and fiber content. Obesity Res
1996; 4: 337-345.
15. Hand M. Effects of low/high fiber in the dietary management of obesity .
Proc 6th ACVIM 1988; 6: 702-703.
16. Butterwick R and Markwell P. Effect of amount and type of dietary fiber
on food intake in energy-restricted dogs. Am J Vet Res 1997; 58: 272-276.
17. Rolls B. Sensory-specific satiety. Nutr Reviews 1986; 44: 93-101.
18. Anand B. Nervous regulation of food intake. Planta Medica 1961; 41:
677-708.
19. Buffington CA. External and internal influences on disease risk in cats.
J Am Vet Med Assoc 2002; 220: 994-1002.
20. Hickman M. Pharmacological therapies for obesity. Proc 23th ACVIM
2005; 23: 1-3.
Nutritional aspects
of obesity
Patrick Nguyen & Marianne Diez (Please refer to page 7 for biographies).
Introduction
Obesity is not just an excess of body weight; it is a
serious disease due to the many accompanying
disorders that it may induce.
The majority of owners of obese animals do not
spontaneously seek veterinary advice to resolve the
problem of excess weight. As a rule, they are not
fully aware of the condition of their animal and it is
therefore up to the practitioner to make the
diagnosis, and convince the owners of the
seriousness of the condition and motivate them to
undertake a diet.
The secondary disorders, exercise intolerance, joint
disease, cardiovascular disease etc., are often delayed
in comparison with the onset of obesity, but the
owners must be convinced as early as possible that
excess weight is not just an aesthetic problem, and
that it requires vigorous and rigorous correction.
Obesity: preliminary steps when
preparing a feeding program
Initial general clinical examination
This first consultation is the perfect opportunity to
take stock of the animal's general status and the
owner’s motive for the consultation. It is important
to establish the severity of the problems detected by
the owner and list those that have yet to become
apparent. A detailed history should be taken of any
previous medication, especially those that could
affect energy metabolism, such as corticosteroids or
progestagens. Behavioral factors should also be
taken into account, such as the temperament of the
animal and level of activity, which is usually
reduced in proportion to the excess body weight.
Management and lifestyle issues such as living
conditions and context, opportunity to increase
energy expenditure, cohabitation with other
animals are also important to identify.
Win over the owner's conviction and
cooperation
As mentioned previously, it is often difficult to get
an owner to admit that their animal is obese,
especially if the obesity has not yet caused any
clinical problems. Additional time is needed during
obesity consultations for the veterinarian to
convince the owner. It is useless to undertake such
a consultation if it is clear that the owner does not
wish to comply or if you do not have adequate time.
Different approaches may be envisaged but it is
often preferable to use positive messages (explain all
the advantages of weight loss for the dog's health:
animal in better health, more alert, longer life)
rather than negative (deleterious effects of obesity,
associated diseases). One should adapt to the
owner, concentrate on the arguments that are most
likely to affect them (longevity, responsibility
towards the animal's health), and the arguments
that are directly related to the animal (improvement
of the clinical signs).
To conclude the initial consultation, one should:
• Agree with the owner on a target weight. The
most important thing is to get them to admit the
necessity for weight loss and the diet and that the
latter will be effective. It is often only after the
initial results that it becomes possible to refine the
prognosis and the objectives.
• Set a clear goal: "your dog must therefore lose this
many kilograms in so many months", is more
likely to convince the client than "your dog is too
fat; we are going to put him on a diet to get him to
lose weight".
• Warn the owner that it is difficult (physiologically), trying (emotionally), and a slow process
to make an animal lose weight, and that they will
therefore need determination and perseverance.
Asking them to weigh the animal once a week
2006
l
Vol 16 No 1
WALTHAM Focus
33
Nutritional aspects of obesity
throughout the period of the diet to monitor the
results can be a way of encouraging them, but it is
above all a way of involving the owner and making
them more rigorous.
Dietary history
An in-depth dietary history should enable evaluation of
the animal's energy consumption at the time of
consultation. Remember that many owners will state
that their pet eats very little, and, even if this is not the
case, it often the owner's impression.
One must not lose sight of the fact that the principal
determining factor for energy expenditure, in a relatively
inactive animal, is its lean mass. Indeed, even when
adipose tissue represents 50% of the animal's weight (a
"normal" value would be around 15%), it would only be
responsible for around 10% of energy expenditure.
Thus, the more obese the animal, the less it needs to eat
with respect to its weight, and this is even more marked
the more inactive it is. The initial dietary inventory
should therefore enable an estimation of the level of
calorie expenditure (equal to ingested energy if the
weight is stable) and, secondly, to ensure, when applying
one of the levels of restriction presented below, that the
prescribed energy ration is not greater than that usually
ingested by the animal.
In extremely obese animals whose energy expenditure,
when their weight is stable, is generally very low, one
should ensure that the quantities of energy provided
by the diet are lower than those that the dog usually
consumes.
The discussion should be based on several general
points, notably the animal's environment (context and
lifestyle, presence of other animals), and its mode of
feeding. One should find out who feeds the animal and
whether several different people are involved. One
needs to find out what the animal usually eats (brand,
type of product), and how much (method of feeding:
ad-lib or restricted quantity), and whether the animal
also receives treats or table scraps, etc.
If the current dietary situation cannot be established
with precision, one can try to obtain information over
a period of observation. The owner should be asked to
continue as normal (which is obviously illusionary)
and make a note of everything that the animal eats
(what, when, how, how much?) and who feeds it for
two or three weeks (the time needed to obtain the
results of complementary examinations) including
titbits and treats. At a second consultation at the end
of this period, the situation can be assessed and a
prescription can be issued that is as perfectly reasoned
as possible.
34
WALTHAM Focus
Vol 16 No 1
l
2006
Obesity: the degree of energy restriction
Once the owner is convinced that weight loss and calorie
restriction are imperative, all that remains is to establish
a forecast of weight loss and to determine the most
appropriate diet for the circumstances and the objectives.
A standard level of restriction?
Different programs have been proposed, often
independently of all reference to the excess weight or to
the level of feeding at the time of consultation. The
most commonly prescribed of these diets only covers
60% (thus a restriction of 40%) of the energy
requirements calculated on the basis of the objective
weight of the animal.
A review of the various studies published shows that
resulting weight loss can vary considerably. Thus, by
applying a 40% restriction in energy intake (i.e. by
providing 60% of requirements) in dogs, we have
observed a weight loss of between 12 and 26% of the
initial weight depending on the individual case, over a
period of between 7 and 16 weeks (1, 2), which
represents a weekly weight loss of 0.72 to 4.26%.
Similarly, by applying a 60% restriction in energy intake
(providing 40% of requirements) for 12 weeks, the
resulting weight loss ranged from 4.8 to 27.8% of the
initial weight (3). Finally, in another study applying a
50% restriction, it took between 40 and 161 days to
achieve the ideal weight (4). Results obtained with obese
cats were just as conclusive and equally variable. A 40%
restriction thus gave a weight loss of 2.4 to 17.1% in 14
weeks (5), whilst a restriction of between 25 and 50%
was needed to induce a mean weekly loss of around
1.5% (6).
These figures show the extreme variability of results
obtained for similar levels of energy restriction and
reciprocally that the same objective can be attained
using different degrees of restriction. The latter is
principally dependent on the extent and origin of the
obesity, and to the amount previously consumed.
A reasoned level of restriction
The choice of the degree of energy rationing should be
adapted as a function of several criteria, notably to the
degree of excess weight (and thus the target weight loss),
the sex of the animal, and the planned duration of the
diet. In a recent experimental study in Beagles, it became
apparent that it was harder to induce and maintain
weight loss in obese females, whether intact or neutered,
than in sterilized males.
One could therefore be tempted to apply a severe energy
restriction to limit the duration of the diet. This is not
recommended. Indeed, overly severe restriction may cause:
• A significant sensation of hunger in the animal
generating increased activity before mealtimes and
discourage the owner
• Excessive lean tissue loss (muscle mass)
• A rebound effect: during the weight loss period, basal
energy expenditure decreases (resistance to weight loss)
and, during the subsequent period of normal feeding,
remains inferior to that of lean animals of the same
weight, thus facilitating weight gain after the diet
• A more marked decrease in physical activity, which
constitutes a second risk factor for reduction of muscle
mass
It is apparent from the various published experimental and clinical studies that a reasonable objective
is to maintain a loss of 1 to 1.5% of initial weight
(obese) per week, equivalent to a loss of 6 to 7.5%
per month. Table 1 indicates varying degrees of
energy restriction as a function of several parameters:
excess weight, male or female, neutered or intact,
breed, and clinical examination.
These figures remind us, as if that were necessary, that a
systematic restriction of 40% is a very crude approach,
with correspondingly varied results.
The approach is exactly the same for cats (Table 2).
However, we do not have as much information available,
notably in terms of any possible male-female differences.
Given that neutering is more and more common in both
sexes, the proposed ration is not differentiated. Moreover,
given the inherent risks of rapid weight loss, and notably
the very real risk of hepatic lipidosis in the event of
anorexia, even if it is not total, a weight loss of no more
than 1.5% of the initial weight per week should be
envisaged. In the most obese animals (those with a
maximal body condition score, regardless of the type of
scoring system used, 5, 7, or 9 point scale), the recom-
mended calculated energy allocation is very low and may
need to be slightly increased, which obviously means
prolonging the probable duration of weight loss.
What weight loss should be anticipated?
Table 1 also shows that, if the initial excess is 40%, a
weight loss of 2% per week should enable the objective
to be attained in around 17 weeks. If it is 30%, 15 weeks
should be sufficient at a rate of 1.75% per week, and if
it is 20%, 12 weeks at an average loss of 1.5% per week
(Figure 1).
If a client brings in a 30kg dog whose ideal weight is
23kg, and in which we want to achieve a weight loss of
5kg (target weight = optimal weight = 25 kg), these 5kg
represent between 35,000 and 40,000 kcal that the
animal must mobilize. If we want it to lose these 5kg in
6 months, the energy intake will have to be reduced
(that calculated on the basis of maintaining the target
weight) by a minimum of 200 kcal per day.
Increasing physical exercise whenever possible enables an
increase in energy expenditure, accelerates weight loss
and decreases the resistance to weight loss.
Finally, we should underline the fact that the most
important point is that the energy intake be effectively
(and not "theoretically") reduced, i.e. less than what the
animal was receiving previously. The dietary history is
made even more important by the fact that for the same
body weight, an obese animal often eats less than a lean
subject. If sufficiently precise information is not available
and a standardized restriction is applied, the owner
should be informed that anything should be expected,
even weight gain, and the next check-up should be
booked (one month later) for a probable if not inevitable
adjustment.
The energy supply is in
theory lower the greater
the excess of weight and
the faster we want to
achieve the target weight.
It is advisable to apply
more drastic reductions in
female than in male
animals.
BCS: Body Condition
Score, on a scale of 1
to 5; TBW: target weight;
Initial Weight: weight
of the obese dog.
Table 1.
Energy intake recommendations for weight-loss programs in the dog
> 40%
> 45%
Excess weight
% body fat
Body condition score (BCS)
20-30%
25-35%
4
Daily energy intake
(kcal ME/kg TBW-0.75)
male
female
male
female
male
female
Loss of 6% of initial weight per month
(around -1.5% per week)
85
75
75
65
60
55
Probable duration of weight loss
15-18 weeks
18-20 weeks
≥ 20-22 weeks
Daily Energy intake
(kcal ME/kg TBW-0.75)
male
female
male
female
male
female
Loss of 7.5% of initial weight per
month (around -2.0% per week)
80
75
65
60
55
50
Probable duration of weight loss
9-11 weeks
30-40%
35-45%
4.5
5
11-13 weeks
≥ 15-17 weeks
2006
l
Vol 16 No 1
WALTHAM Focus
35
Excess weight
% body fat
20-30%
25-35%
30-40%
35-45%
> 40%
> 45%
Body condition score
(BCS)
4
4.5
5
Daily energy intake
(kcal ME/kg TW)
30
25
20
Probable duration
of weight-loss
15-18 weeks
18-20 weeks
≥20-22 weeks
Obesity: a logical approach to formulating
a ration
It is totally contraindicated to restrict the intake by
simply restricting the quantity of food usually
consumed. This option leads to nutritional deficiencies
and is unlikely to be successful. The formulas therefore
need to be adjusted, both in terms of energy and
nutrients (proteins, essential fatty acids, minerals,
vitamins) as well as in terms of "volume" (fiber). Finally,
one can envisage the use of molecules or specific
ingredients that could improve the slimming potential
of the feed.
Adjustment of the protein-calorie ratio (PCR)
In the context of weight loss, the protein-calorie ratio
(PCR), expressed in grams of proteins per mega calorie
of metabolizable energy (g/kcal ME), should be greatly
increased in comparison with the recommended
maintenance value. The rationale for the increase in
PCR can be justified on physiological and mathematical
grounds and exploits the properties and advantages of
protein.
An essential adjustment
The protein concentration of diets destined for the
nutritional treatment of obesity should, to cover the
requirements in essential amino acids or not, be well
above those of rations recommended for maintenance.
Since the energy intake is greatly reduced, the protein
concentration (PCR) must be increased in inverse
proportion to prevent reducing protein intake (grams per
day) below physiological requirement. An animal's
protein requirements are essentially determined by its
lean mass and are therefore, in first approximation,
linked to its ideal weight (the fat mass only contributes to
around 5% of energy expenditure, and has an almost
negligible contribution to nitrogenous expenditure).
The protein intake should also be increased when
significant quantities of dietary fiber are incorporated,
due to the decreased digestibility that the latter provokes.
The same reasoning also applies, on both these fronts,
for all essential nutrients.
36
WALTHAM Focus
Vol 16 No 1
l
2006
The advantages of protein
High protein diets have been used with great success for
many years in man and have, other than the
physiological imperative explained above, demonstrated
numerous advantages:
• Decreased net energy return compared to
carbohydrates and lipids
• A positive effect on body composition whilst
preserving lean tissue mass: diets with a high protein
content make it possible to increase the loss of fatty
mass and to minimize the loss of lean tissue
• Food rich in proteins provides greater satiety than food
rich in carbohydrates or lipids
• A beneficial effect on satiety, which compensates (more
or less) for the decreased levels of lipids and the
increased fiber content;
• Improved preservation of weight loss after an ideal
weight is attained and the diet is suspended
It is therefore imperative to significantly increase the
PCR of the food, provided that renal function is
normal.
Although it has been demonstrated that the speed of
weight loss is also a determining factor (7), it has also
been demonstrated that the higher the PCR, the lower
the loss of lean mass, for an identical weight loss (8).
Dietary fiber
The incorporation of fiber, whether more or less soluble,
is not uniform in low energy diets but is nonetheless one
of the primary means of decreasing the energy density of
feeds and thus ensuring a satisfactory volume for a
reduced energy content.
In the dog, energy restriction obtained by administering
a diet with high fiber content but also low lipid content
has enabled a greater reduction in body fat and serum
cholesterol concentrations (9).
In general, the majority of studies available suggest that
fiber is beneficial in the diet of obese patients: It affects
satiety and digestibility. Increasing fiber has advantages
and disadvantages, in addition to some, albeit small,
energy value:
Goal 1%
Goal 2%
Bodyweight kg
Table 2. Energy intake recommendations for
weight-loss programs in neutered cats
Time, weeks
Figure 1.
Examples of
decreasing
weight graphs for
a Beagle with an
amount of excess
weight of 20 %
(Initial weight:
16.8 kg, optimal
target weight: 14
kg). Ideally , the
goal should be to
achieve 2% body
weight loss per
week.
Some advantages of increasing fiber in the diet:
• In the dog, although it is harder to evaluate the
sensation of satiety than in man, diets with high levels
of fiber seem to improve satiety (10)
• Fiber increases the volume of intestinal chyme, thus
diluting enzymes and the constituents of micelles. It
can adsorb enzymes, bile salts and phospholipids. All
of which slows the solubilization of the constituents of
the food, their digestion and their absorption, thus
decreasing their digestibility.
Some disadvantages of increasing fiber in the diet:
• An increase in the quantity of feces and the frequency
of defecation
• A decrease in the digestibility of certain nutrients such
as proteins and minerals
• The inherent energy value of fermentable fiber is
poorly understood in carnivores but is estimated at
around 1-2 kcal ME/g in man. This lack of
information makes it difficult to define an optimal
concentration
• Despite controversy over the hunger-satisfying
properties of dietary fiber, increasing the fiber content
of food would seem to be a good way of reducing its
energy density whilst maintaining an acceptable
volume, if not for the animal (satiety?) then for the
owner
Nevertheless, their negative effect on the digestibility
of certain essential elements should be taken into
account (by increasing their concentration), as well
as the possible and non-negligible energy value of
fermentable fiber.
Other adjustments
Lipids
The lipid content of low energy foods should obviously be
reduced due to their high energy density. Nevertheless, it
is also quite clear that a minimum content is necessary to
cover essential fat acid requirements and enable the
absorption of fat soluble vitamins. The most recent
recommendations are for a minimum of 15g/kcal ME
(around 5% for a feed containing 3,300 kcal ME/kg).
It is almost imperative to significantly reduce the fat
content of diets.
Assimilable carbohydrates
Once the protein, fiber, and fat content have been
adjusted, it is not difficult to deduce the place reserved
for assimilable carbohydrates. Their nature is more
important than their quantity, which is of little interest.
The notion of the glycemic index was developed as a
means of predicting the glycemic response following the
ingestion of carbohydrates and is used when formulating
diets for diabetics and, to a lesser extent, low-energy
diets. A low glycemic index also generally signifies a
decreased insulin response, favorable to the mobilization
of fats.
Other nutrients
The vitamin and mineral content should be increased in
proportion with the energy restriction if their
concentration is not to be too low, particularly if dietary
fiber is increased.
As for protein, the vitamin, mineral, and trace element
content of low-energy diets should be increased
compared to that of maintenance diets. Restricting
the energy intake should not result in deficiencies.
Specific ingredients and nutraceuticals
Certain specific ingredients, notably those influencing
lipid metabolism and, beyond that, the body
composition, may be incorporated into low-energy
diets. Here we have cited only three, which are of
current interest:
• L-carnitine improves nitrogenous retention and
modifies the body composition in favor of lean body
mass (11). It can therefore be recommended for obese
animals on a low-energy diet, as well as later to prevent
a subsequent rebound effect
• The two conjugated fatty acids derived from linoleic
acid, known as CLA (conjugated linoleic acids) could
exert an anti-adipogenic action (12); a positive effect on
the body composition has been demonstrated in the dog
• Extracts of Garcinia Cambodia, whose principle
actives are AHA (alpha hydroxy-citric acids), inhibit
hepatic lipogenesis (13). Several clinical studies carried
out in obese patients have yielded contradictory results
Practical approach
Some habits have to be changed
Various epidemiological studies have demonstrated a
number of risk factors for obesity in animals' lifestyles
(refer to Alex German’s paper in this issue)
The diet must be changed
As we have indicated, the choice of diet will first take
into account its objective (the treatment of obesity), and
possibly the speed of the planned weight loss. The diet
should have an appropriate protein-calorie ratio, whose
energy value (largely determined by the dietary fiber
content) will be as low as possible whilst enabling an
acceptable feeding ration and volume for the owner that
is sufficiently filling (even if it is only short term) for the
animal.
Dividing the daily ration into 3 or 4 small meals could
increase postprandial thermogenesis. It is also a good
2006
l
Vol 16 No 1
WALTHAM Focus
37
way of reducing the length of time that the animals go
hungry thus limiting hyperactivity at mealtimes.
A home prepared ration is also theoretically possible, even
though it is always more difficult to guarantee a balanced
diet, if only due to the risk of variation of the quality of
the ingredients or the ways in which they are prepared.
A follow-up is essential
Drawing up a weight loss curve enables the owner to
visualize the progress obtained. It is usually a good
motivating factor. When drawing up the program, an
individualized weight loss curve is established with the
initial weight of the animal and two curves
corresponding to a weight-loss of 1 and 2% per week,
the owner's objective being to maintain the weight of
their animal between these two curves.
They should then be asked to weigh their animal once
weekly, always under the same conditions (in the
morning before the first feed for example) and,
obviously, using the same set of scales.
It is also a good idea to ask the owner of an obese animal
to come back for a check-up every 4-6 weeks to carry out
a clinical examination, assess the behavioral aspects and
adjust the feeding program (type and quantity) where
necessary.
Good communication with the owner is vital
Firstly, they should be reminded that given the
prescribed program will be re-evaluated (after 4-6
weeks). They should also be informed that in some
animals with very low initial energy expenditure a
standard program might not induce weight loss. They
should however be told that at the time of the reevaluation, we will have all of the elements (evolution of
the weight for an exactly known energy ingestion)
needed to establish a definitive program.
One should not lose sight of the fact that although,
theoretically, success is guaranteed if the program is
correctly adapted and adhered to, in practice, the
prognosis depends primarily on the owner's motivation.
Correct communication is often the guarantor of
success.
Conclusion
In conclusion, we should remember the following major
principles that generally guarantee the success of a
nutritional treatment program for obesity in pets:
• Evaluate the previous diet
• Evaluate its body condition score
• Stress the clinical benefits of weight loss to the owner
• Determine a level of rationing: as a function of current
food intake, the breed, age, sex etc. and the weight, the
initial weight and the target weight
• Use a specifically formulated low-calorie weight loss
diet
• Carefully weigh out the quantity of food perhaps
dividing into three to four meals
• Set a realistic time frame and encourage the owner to
persevere
• If weight loss is less than 1% or more than 3% weight
loss per week, readjust energy intake accordingly
• Suggest, whenever possible, increasing the level of
physical activity. u
references
1. Biourge V, Henroteaux M, Istasse L, et al. Traitement d'un cas d'obésité chez
une chienne. Ann Med Vet 1987; 131: 419-424.
2. Laflamme DP, Kuhlman G, Lawler DF. Evaluation of Weight Loss Protocols
for Dogs. JAAHA 1997; 33: 235-239.
3. Markwell PJ, van Erk W, Parkint GD, et al. Obesity in the dog. J Small
Anim Pract 1990; 31: 533-537.
4. Blanchard G, Nguyen P, Gayet C, et al. Rapid Weight Loss with a HighProtein Low-Energy Diet Allows the Recovery of Ideal Body Composition and
Insulin Sensitivity in Obese Dogs. J Nutr 2004; 134: 2148S-2150S.
5. Hand MS. Effects of low fat/high fiber in the dietary management of
obesity. Sixth Annual Vet Int Med Forum, ACVIM Proceedings 1988; 702.
6. Nguyen P, Dumon H, Martin L, et al. Weight Loss Does Not Influence
Energy Expenditure or Leucine Metabolism in Obese Cats. J Nutr 2002; 132:
1649S-1651S.
7. Prentice AM, Goldberg GR, Jebb SA, et al. Physiological responses to
38
WALTHAM Focus
Vol 16 No 1
l
2006
slimming. Proc Nutr Soc 1991; 50: 441-458.
8. Diez M, Nguyen P, Jeusette I, et al. Weight Loss in Obese Dogs: Evaluation
of a High-Protein, Low-Carbohydrate Diet. J Nutr 2002; 132: 1685S-1687S.
9. Wolfsheimer J, West DB, Kiene J, et al. Differential metabolic effects of
caloric restriction using high-fat vs low-fat diets in dogs. J Vet Int Med 1994;
8: 154.
10. Jewell DE, Toll PW, Novotny BJ. Satiety reduces adiposity in dogs.
Vet Therapeutics 2000; 1: 17-23.
11. Gross KL, Zicker SC. L-Carnitine increases muscle mass, bone mass, and
bone density in growing large breed puppies. J Anim Sci 2000; 78: 176.
12. Azain MJ. Conjugated linoleic acid and its effects on animal products and
health in single-stomach animals. Proc Nutr Soc 2003; 62: 319-28.
13. Westerterp-Plantenga MS, Kovacs EM. The effect of (-)-hydroxycitrate on
energy intake and satiety in overweight humans. Int J Obes Relat Metab Disord
2002; 26: 870-872.
The Royal Canin Cut-out & Keep guide
Body condition scoring
in cats and dogs
Author: Marianne Diez
(Please refer to page 2 for biography)
T
he combination of data on stature and on body
weight introduces the concept of morphometric
techniques to evaluate body composition. Morphometry
measures the outer form, evaluates certain body regions
and how their dimensions change and shows their
relationship to the modifications in the body composition.
The morphometric techniques used on dogs are body
condition scoring and techniques that combine diverse
body parameter measurements (length and circumference
of various parts of the body).
"
The body index is a semi-quantitative subjective
evaluation method combining the evaluation of visible
characteristics and a palpation of certain regions of the
body. This evaluation is conducted in accordance with
simple criteria: the size and location of major adipose
deposits, the visible and invisible skeletal structure, and
the silhouette of the animal.
Several types of index have been proposed:
• 3 grades: 1 = slim, 2 = optimal, 3 = excessive
• 5 grades: 1 = gaunt, 2 = slim, 3 = optimal,
4 = overweight, 5 = obese (Edney & Smith, 1986)
(Tables 1 & 2)
• and even 9 grades: 1-4 = emaciated to slim; 5 =
optimal; 6-9 increasingly overweight (Laflamme, 1993;
Laflamme et al, 1994).
Table 1. Body condition scoring in cats
• Ribcage, spine, shoulder blades and pelvis easily visible (short hair)
• Obvious loss of muscle mass
• No palpable fat on rib cage
Emaciated
• Ribcage, spine, shoulder blades and pelvis visible
• Obvious abdominal tuck (waist)
• Minimal abdominal fat
Thin
• Ribcage, spine not visible but easily palpable
• Little abdominal fat
Ideal
• Ribcage, spine not easily palpable
• Abdominal tuck (waist) absent
• Obvious abdominal distension
Overweight
• Massive thoracic, spinal and abdominal fat deposits
• Massive abdominal distension
Obese
2006
l
Vol 16 No 1
WALTHAM Focus
39
The Royal Canin Cut-out & Keep guide
Table 2. Body condition scoring in dogs
• Ribcage, spine, shoulder blades and pelvis easily visible (short hair)
• Obvious loss of muscle mass
Emaciated
• Ribcage, spine, shoulder blades and pelvis visible
Thin
• Ribcage, spine, shoulder blades and pelvis not visible but easily palpable
• Thin layer of fat tissue palpable on rib cage
Ideal
• Ribcage, spine, shoulder blades and hipbones palpable with difficulty
• Abdominal tuck (waist) absent
• Fat deposit obvious on spine and base of tail
Overweight
• Massive fat deposits on thorax, spine and base of tail
• Obvious abdominal distension
Obese
The dogs presenting an average index corresponding to
an optimal weight have a fat mass of around 13%.
When a 5-grade body index is used, every half-grade in
the index represents a 10%-increase in fat mass. As a
consequence, a dog presenting a body index of 5, which
corresponds to the qualification ‘morbid obesity,’ has a
fatty mass of over 40%.
The advantage of these index systems is that they can be
easily applied by the clinician and that they do not apply
exclusively to the diagnosis of obesity but also to its
active prevention. It is easy to weigh the animal during a
routine consultation and find the value in the index. u
Further Reading
Edney ATB, Smith PM. Study of obesity in dogs visiting veterinary practices in
the United Kingdom. Vet Rec 1986; 118: 391-6.
Laflamme DP. Body condition scoring and weight maintenance, in
Proceedings. The NA Vet Conf, 1993, 290-291.
40
WALTHAM Focus
Vol 16 No 1
l
2006
Laflamme DP, Kealy RD, Schmidt DA. Estimation of body fat by body
condition score. J Vet Int Med 1994; 8: 154A

16.1 Anglais_Focus

Transcription

Similar documents

Nothing to do - Rabbit Welfare Association

Coleus canina

conference schedule - icelandichealthsymposium .is

Shampoo A7 Quick Guide

Outnumbered: The BAD CATS Learn About Numbers

PDF

hillsiders - Hillside Veterinary Centre

General Public

Arnold Schwarzenegger is obese. He`s been obese his entire adult

event Partners aCtIvItIes