Periapical tooth root infections in South American camelids

Periapical tooth root infections in South American camelids
David E Anderson, DVM, MS, Diplomate ACVS
College of Veterinary Medicine
The Ohio State University, Columbus, Ohio, USA
Dr Anderson began his presentation with a short personal history. His first encounter with camelids
was a single case with an obnoxious owner whilst working at the University of Georgia during his
first year after graduating. Later, in Kansas, he found much nicer owners who were willing to travel
long distances to find an interested vet. However, it was at the University of Ohio that he began to
specialise in camelids. When he arrived, OSU was offering farm animal surgery and a post mortem
service for camelids – 80 or so a year. Dr Anderson began by expanding into farm animal medicine
and was more than happy to include camelids. With an annual case load growth of 300% over the first
4 years, his department now sees over 1000 camelids each year, generating $0.5million. In addition,
limited consultations for four or five large herds provides cover for a further 4000 animals.
The local llamas are primarily companion animals. Some elite breeders are selling individuals for
$10,000 - $20,000 but overall the average sale price is $200 - $2000.
The USA alpaca industry has an annual growth rate of 25% with 1000 new farms each year. A
breeding female can cost $20,000 (range $8,000 – $150,000), a top quality breeding male (1% of
males born) from $20,000 – $260,000. Recently a male sold for $220,000 but had bookings for 100
breedings at $5000 each before leaving the auction area. At the same auction, a group of 68 animals
sold for $2.3 million. In other words, these are valuable animals, owners are prepared to pay for
treatment and currently alpacas make up 70% of the case load.
The treatment of facial abscesses at OSU is lucrative, generating $50,000 yearly. This is because it is
the only establishment within a 2000 mile radius willing to attempt treatment.
Facial swellings
Dental
abnormalities
are
a
relatively common occurrence
in
camelids.
Veterinarians
are being asked to evaluate
facial
“swellings”
as
owner
awareness of dental problems
in their animals is increasing.
Accurate diagnosis is important
to
differentiate
facial
swelling
in
causes
of
order
to
provide optimal treatment and
prognosis.
Alpaca with right mandibular
swelling
British Veterinary Camelid Society
Proceedings of 2003 annual conference
The most common complaint by owners is persistent facial swelling. The swelling may appear to enlarge
rapidly (soft tissue abscess), be slowly progressive (osseous remodelling), or persist unchanged for
months. Weight-loss, lethargy, anorexia, dropping of feed, and foul odour of the breath are also
described. Retention of food boluses in the cheek is occasionally observed. The OSU team has treated
tooth root infections in animals ranging in age from four months to 14 years, although most affected
animals are six to 10 years old (Coyne, et al) and finds that periapical tooth root abscesses rarely
open and drain to the exterior of the face but typically drain into the oral cavity.
Tooth anatomy and eruption
Eruption Time
Tooth
Deciduous (1/3,1/1,2-3/1-2,0/0)
Adult (1/3,1/1,1-2/1-2,3/3)
I1
birth
2 years
I2
birth
3 years
I3
birth
3 to 6 years
C1
+/-, usually -
2 to 7 years
PM3
birth
3.5 to 5 years
PM4
birth
3.5 to 5 years
M1
---
6 to 9 months
M2
---
1.5 to 2 years
M3
---
2.75 to 3.75 years
Note that other
authorities
the
4
incisor
class
upper
th
as
upper
an
canine,
making a total of
six fighting teeth
in the adult – two
upper
and
one
lower canines on
each side.
Underlying
anatomy
can
be
found
in
Dr
Spurgeon’s
Anatomy of Large
Animals.
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Adult dentition
The sharp, jagged edges on the occlusal surfaces of the cheek teeth are necessary for the chewing
style of crushing and cutting and a flat tabular surface is a sign of dental ageing, leading to inefficient
chewing and weight loss.
Unless there is misalignment or disease, the best advice is not to float. This contrasts with the scissor
and grinding action of the horse where a flat tabular surface is the norm. In fact the only routine
dentistry which might be needed is to keep the lower incisors flush or within 5mm of the dental pad.
Increased length of the incisors leads to abnormal mechanical stresses on the mandible and hence
abnormal alignment of the cheek teeth.
A diamond edged Dremel bit performs a neat job with minimal fragmentation when compared with a
grinder or side cutter and provides a better view than a guarded incisor cutter.
Fighting teeth
In llamas the fighting teeth can often be felt below the gum line before they erupt at around the age
of two to three years. They are usually small and insignificant in females, small and slow to erupt
in males castrated at less than two years, but can be used as formidable weapons by entire males.
Used as the main tool of inter-male dominance, these curved teeth can be fixed into an opponent’s
ventral neck and a swift pull can fatally damage the trachea, carotid arteries and jugular veins. As
the mouth can open to only 30°, if aimed at the back of the neck these backward curving teeth
can become embedded in the nuchal ligament and require sedation to remove. Such wounds often
become abscessed. These problems can be prevented in entire males by removing the fighting teeth
just proud of the gum line using cutting wire. Starting at the age of 3, the procedure can be repeated
as needed (often only once yearly) until the teeth stop growing at approximately 7 years old.
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Underlying pathology
Damage at the gum line from stemmy hay or thistles and briars can lead to secondary abscessation. It
is advised that all abscesses be cultured as a matter of routine. Although the underelying mechanical
cause is identical to lumpy jaw in cattle, the infectious agents differ. In camelids, infection is more
likely to be staphylococcal, streptococcal or more rarely fungal rather than Actinomyces bovis, though
Arcobacter pyogenes has been reported.
One farm had a problem with methacillin resistant Staph aureus (MRSA), thought to be transmitted
from a human. Eight animals were affected but the infection resolved spontaneously after six months.
Neoplasia is rare although squamous cell carcinoma has been reported. Tuberculosis as a cause of
mandibular swelling has been seen in New Zealand, though not in the USA.
C o r y n e b a c t e r i u m
pseudotuberculosis, the cause of
caseous lymphadenitis in sheep
and goats, has also been implicated
in camelid facial abscesses. In
small ruminants both the visceral
(fading goat/thin ewe syndromes)
and cutaneous (lymphadenopathy,
abscesses
or
exuding
wounds)
forms are recognised. In cattle and
horses, infection is more likely to
be seen as ulcerative lymphangitis.
Lesions in sheep tend to be of the
caseated onion-skin type, but in
goats, the pus is more likely to be
Caseous lyphadenitis
liquid.
Alpacas seem more resistant than sheep and the condition is most likely to present as sporadic
abscesses rather than insidious chronic disease. Superficial, liquid abscesses are most common but
the visceral form with involvement of the mediastinal lymph nodes has also been seen, fortunately
not followed by chronic wasting disease.
C. psuedotuberculosis is a facultative gram positive coccobacillus which can survive in soil for years.
Lancing of abscesses in the field may lead to environmental contamination as bacteria can be shed
in exudates for more than 30 days. Infection may be transmitted from a discharging abscess via
superficial skin damage or contamination of food and entry via oral abrasions, especially during
teething. In sheep the visceral form can lead to infection via aerosol but prolonged contact is
required.
Antibiotics alone are rarely successful and are best used after surgical excision of the lesion and any
affected lymph nodes – the aim is to remove all active infection before there is any internal spread.
General anaesthesia will be required but the operation is fairly straightforward as there is less soft
tissue compared to the sheep or goat. Early detection and isolation, followed by effective treatment
can prevent spread to others.
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However, herd outbreaks have been seen - in one case 6 youngsters from 2 to 14 months of age
were affected within a 2 month period, possibly after contact with an affected animal in a community
trailer. The haemolytic synergistic inhibition test was used for herd monitoring. All tested negative
except the 6 affected individuals who were treated surgically, given antibiotics, then kept isolated
from the rest of the herd. The herd was checked every 3 months for 1 year then every 6 months for
2 years, but no further cases were detected. Once further testing showed that 4 of the 6 had become
seronegative, they were returned to the herd. The remaining two were kept isolated for 2 years but
remained seropositive so were culled and found to have chronic active inflammatory lesions in the
mediastinal lymph nodes.
Physical examination and differential diagnoses
Physical examination is normal except for a focal, hard swelling in the region of the affected tooth.
This swelling is usually associated with oedema and has a soft centre. Occasionally, a draining tract
is present, but, more commonly, the skin overlying the swelling is intact. These lesions are most
commonly seen along the horizontal ramus of the mandible (>90%), and, less commonly, the maxilla
(<10%) and affect the premolars or molars. However, the OSU team has treated a 6-month-old
cria with tooth root abscesses of the right incisors -1,2, and 3, and an adult male with a tooth root
abscess of the right canine tooth. Differential diagnosis for facial swellings should include tooth root
abscess, osteomyelitis (including Actinomyces bovis), soft tissue abscess (including Corynebacterium
pseudotuberculosis), foreign body, parotid duct lesion, facial bone fracture, retained food bolus, and
malocclusion.
At least 50% of cases have no external drainage, though many will drain into the mouth. Often
there are no external clinical signs except perhaps weight loss, and the condition is first noticed as
a hard bony swelling at shearing in the spring. Except in especially severe chronic cases, the root
of the affected tooth is still alive, but the bone around the root is usually affected (periapical tooth
root infection). Almost always the condition is secondary to penetration of the periodontal ligament,
especially when the molars are erupting between 2 and 6 years of age. On histopathology, plant
material is often found deeply embedded in the bone and the condition can be associated with the
style of feeding – both oat hulls and poor quality stemmy hay have been implicated.
Radiographic imaging
Radiographs are indicated for diagnosis of periapical tooth root abscess. Try to routinely obtain
dorsoventral, lateral, and dorsolateral to ventrolateral oblique views of the affected side.
When contemplating surgery on a mandibular tooth, Dr Anderson has started using intraoral dental
film to better evaluate the affected tooth and mandible. All views are obtained while the animal
is heavily sedated or anesthetised. Occasionally, an abscess will be found on the medial aspect of
the tooth root where is not obvious on standard views. This location of a bone abscess predisposes
the mandible to fracture while tooth repulsion is being done. Tooth root debridement or root canal
treatment is unlikely to be successful if a bone abscess is present and not treated.
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Also, radiographs may
help to determine the
cause of the infection.
Tooth
root
infections
may be associated with
fracture of the mandible
or maxilla, retention of
a deciduous tooth root,
disruption of the gingiva
or periodontal lesions,
cracking of the tooth, or
a patent infundibulum.
Normal anatomy and
time
of
the
various
must
be
when
eruption
of
teeth
considered
interpreting
radiographs
of
the
skull.
Look for a break in the dura, a widening of the space between tooth and dura or resorption of the
medial alveolar plate. If available, computerised tomography scanning will show compromise of the
medial alveolar wall extending to the gum line. Interestingly, despite routine trimming of the fighting
teeth, they are rarely affected. However, it is best to leave approximately 2mm protruding above the
gum line to prevent penetration of the pulp cavity. This also prevents traumatic gingivitis which can
lead to anorexia lasting several days.
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Although 95% of dental
abscesses are found in the
mandible,
post-mortem
examination often reveals
undiagnosed
maxillary
abscesses. These rarely
show
as
an
external
swelling and if they drain
at
all,
drain
into
the
nose, mouth or a sinus.
However, weight loss may
ensue and if investigations
of all other causes have
proved negative, a CT
scan
might
problem.
the
locate
the
Unfortunately,
maxillary
sinus
in
camelids is too small to
allow drilling and endoscopy to view tooth roots as in the horse.
In older animals there tends to be bone resorption around tooth roots together with a widening of
the periodontal membrane, so predisposing to periodontal infection. This may be due to vitamin
D/calcium/phosphorus inbalance leading to decreased bone density, especially over winter – a good
topic for future research. Shearing off of the crown, exposing the pulp cavity and leading to infection
tracking to the root is seen in only 10% of cases, mainly older animals, and may be associated with
routine floating of the cheek teeth. A further 10% of cases are associated with retained deciduous
caps. Osteomyelitis can be seen at any age – in the very young it is most likely due to haematogenous
spread from another infected site. Periapical osteomyelitis with death of the root is most likely to
affect M1 or M2 followed by PM4 then M3.
Recommended treatment and surgical approach
Tooth root infections may be left untreated, be treated with long-term antibiotics, by curettage, by
root canal treatment, or the affected tooth (or a portion of it) may be removed. For pregnant females
in which clinical signs are mild, the OSU team delays treatment until after parturition or at least until
after the fifth month of gestation. They have treated more than 10 pregnant females in the last three
years; to their knowledge, one female aborted 60 days after surgery (reason undetermined) and all
other females carried their crias to term.
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If the patient is in good condition and the only clinical finding is a small, well circumscribed jaw
nodule, treatment may not be necessary and the nodule will often resolve spontaneously. However,
if there is any weight loss or dysphagia then action will be needed. Medical treatment alone is rarely
successful, even if given for prolonged periods – one Michigan owner gave antibiotics twice daily
for 18 months before accepting that surgery would be necessary. Even if antibiotics initially seem
successful, recurrence is common – the dead root acts as a nidus for reinfection and the impacted
vegetation and bone resorption may have left chunks of dead enamel in the middle of a sea of
infection.
If the dura is eroded from the medullary surface, contamination of adjacent teeth is common as the
roots almost touch. Conversely, as there is no communication between root cavities, it is possible to
amputate a single infected root, leaving the healthy root and crown in situ.
It is possible for the body to wall off infection, leaving a shelf of bone on the medial aspect, in
effect forming a new mandible. In this case it would be necessary to remove the outer cortex of the
old mandible and debride all pus and granulation tissue. Infection can also penetrate into alveolar
bone, leading to osteomyelitis which can affect adjacent teeth. Debridement, effective drainage and
antibiotics will either solve the problem or give time to detect the original problem tooth so that it can
be extracted later. In 1% of cases, severe osteomyelitis has resulted in very poor bodily condition so
that surgery cannot be contemplated.
In Dr Anderson’s experience, tooth removal effectively resolves the infection with few complications.
However, other surgeons have had success by performing curettage or root canal treatment. The
only disadvantage of these techniques is the expense suffered by the client if the surgeon must
repeat the procedure or remove the tooth if the treatment fails and there are continued clinical signs
associated with the infection.
For surgical treatment general anaesthesia will be needed, often for a prolonged time. A combination
of xylazine/butorphenol/ketamine will give 20-30 minutes surgical time and can be extended with a
further 1/3 to 1/2 dose after 15 minutes if needed. If the procedure is expected to last longer than
45 minutes, intubation is preferred.
Mandibular tooth extraction
Surgical extraction per os is rarely possible due to the limited opening of the camelid mouth. Because
of the relatively thin mandible of the camelid, do not be tempted to repel the tooth as in the horse
– there is often little medial support left and the mandible is easily fractured.
If the affected tooth is loose it can be extracted with forceps, the socket debrided and antibiotics
prescribed. However, if it is not loose, make a lateral crescent shaped incision over the swelling,
either trans-cutaneously or trans-bucally; reflect the periosteum and resect the bone overlying the
lateral aspect to allow removal of the affected tooth. Dr Anderson uses a Hall air-drill with burr
attachments to facilitate removal of the lateral bone plate. This practice leaves a smooth bed of bone
that may cause less of a cosmetic defect compared with traditional ronguers or osteotome as the
mandible heals. A lower cost option is to use a Dremel tool.
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Maxillary tooth extraction
Maxillary teeth are somewhat more challenging to remove. Intraoperative radiographs are very useful
to guide dissection. The maxilla is easier to fracture than the mandible but these teeth can be equally
as difficult to repulse. The parotid duct (externally) and the nasolacrimal duct (internally) should be
avoided during dissection and repulsion.
The parotid duct enters at the level of upper PM4/M1. If the approach is made cranial to this area, in
the centre of the buccal space, the facial nerve will also be avoided. If a more posterior approach is
necessary, use an elevator to reflect the periosteum towards the crown so that any nerves or ducts
are protected.
A frontal sinusotomy may be needed to repel the tooth downwards into the mouth. Although this
usually destroys the maxillary shelf, the periosteum and muscle usually heal well and provide
adequate support.
Post-operative management
After the tooth is removed, the defect may be packed with dental acrylic but Dr Anderson prefers to
leave a portion of the wound open for daily wound treatment. Even if two adjacent teeth are removed
leaving a large defect, it is better to leave it open to drain, asking the owner to flush with dilute
Betadine. Take care that this is diluted properly as swallowing of excess iodine can lead to death of
the rumen microorganisms. The wound should be flushed once or twice daily until completely filled-in
by granulation tissue (usually 14 to 21 days).
Use of perioperative antibiotics is continued for 10 - 14 days after surgery (Procaine penicillin G, Naceftiofur, or Ampicillin). Antibiotic selection may be changed based on results of microbial culture and
sensitivity of bone samples obtained during surgery. The most common bacteria cultured from these
lesions include Bacteroides sp., Actinomyces sp., and Peptostreptococcus sp. (Coyne, et al.).
Rifampicin and isoniazid can be given orally but cover only a narrow spectrum so must be combined
with penicillin. Enrofloxacillin can be given S/C or orally once daily at 10 mg/kg (double the S/C dose
rate). Oral trimethoprim/sulpha
is not recommended once the
rumen
starts
functioning
at
eight weeks of age but this
antibiotic
gives
good
cover
when given systemically.
After
extraction,
molar
drift
tends to occlude the gap and
as tooth growth ceases with
increasing age, so overgrowth
of the opposing tooth tends not
occur.
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Complications of disease or treatment
Complications of tooth root infection are not well documented. Certainly, weight loss, anorexia and
difficult mastication are the most commonly described. To Dr Anderson’s knowledge, septicemia,
endocarditis, and bacterial embolization of internal organs have not been diagnosed in camelids.
Complications of treatment include osteomyelitis, bone sequestra, damage to adjacent tooth roots or
teeth, fracture of the mandible or maxilla, and aspiration pneumonia.
Entrapment of salivary ducts in healing tissue can lead to the development of post-operative salivary
fistulae – oro-cutaneous if affecting the mandible, oro-nasal sinus if affecting the maxilla. The
constant loss of bicarbonate in saliva can lead to a profound acidosis which can be prevented by
giving 1 tablespoonful of baking soda once or twice daily as a drench. However, the problem will not
resolve until the site is revised and the leaking duct repaired.
A bone or enamel sequestrum may form if the tooth crumbles as it is extracted.
Success rates
Extraction, preferred by alpaca clients
90% success rate
Root amputation, preferred by llama clients
75% success rate
Antibiotics and curettage
60% success rate
Antibiotics alone
30-40% success rate
Prevention
Some individuals are predisposed to dental abscesses, either because of anatomy or feeding
practice.
Feed good quality hay to avoid damage by tough stems. One client was offered free of charge a batch
of round bales destined for cattle. Six weeks later, 15 individuals had dental abscesses. There were
no further problems once he returned to using good quality hay.
Do not routinely float cheek teeth.
Overview
Tooth root infection is a relatively common problem in camelids. Owner and veterinarian awareness
is probably responsible for the increasing frequency of diagnosis of these lesions. Dental surgery
in camelids can be rewarding, but proper facilities and equipment should be available for optimal
treatment and outcome.
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