Annual Screening for Vector-borne Disease, The SNAP® 4Dx® Plus

Annual Screening
for Vector-borne Disease
The SNAP® 4Dx® Plus Test Clinical Reference Guide
Every dog, every year
Know more with every result
For healthier pets and so much more. The benefits of vector-borne disease screening go far beyond the
well-being of an individual pet. Adopting regular screening protocols at your practice can lead to a greater
awareness and understanding of vector-borne disease in your community, while building the value of your
practice with pet owners.
With the SNAP® 4Dx® Plus Test, a positive result can also be an indication
of ticks and other pathogens in your area.
Your patients
Your community
Your practice
Educating pet owners about the
risk of vector-borne disease is an
opportunity to stress the importance
of screening and prevention.
Comprehensive annual screenings
give you a current snapshot of how
widespread certain diseases and tick
species are in the area.
Vector-borne disease screenings
are the foundation of your practice’s
preventive medicine programs and
let you know what your patients are
being exposed to over time, which
leads to healthier patients and a
stronger practice.
When you use the
SNAP® 4Dx® Plus Test
as a screening tool,
you may
detect antibodies to
these pathogens
carried by
these ticks
that may also transmit
other infections to
dogs and people
Ehrlichia ewingii
Lone star tick
Ehrlichia chaffeensis
Amblyomma
americanum
Tularemia
Rocky Mountain spotted fever
STARI
Anaplasma
phagocytophilum
Deer tick or
black-legged tick
Bartonella spp.
Borrelia burgdorferi
(Lyme disease)
Ixodes scapularis
Ixodes pacificus
Ehrlichia canis
Brown dog tick
Babesia spp.
Anaplasma platys
Rhipicephalus
sanguineus
Rocky Mountain spotted fever
Ehrlichia canis
American dog tick
Rocky Mountain spotted fever
Dermacentor
variabilis
Tularemia
Babesia spp.
Geographic tick
distribution as
of 2011
Lyme disease
Canine anaplasmosis
Canine ehrlichiosis
Transmitted by the deer tick
or black-legged tick, Lyme
disease is caused by the
bacterium Borrelia burgdorferi.
Clinical signs may not appear
until several months after
infection. Lyme disease has
been found throughout North
America with cases ranging
from mild to severe.
Canine granulocytic anaplasmosis
is caused by the bacterium
Anaplasma phagocytophilum
(transmitted by the deer tick or
black-legged tick). Anaplasma
platys (transmitted by the brown
dog tick) is the cause of infectious
cyclic thrombocytopenia.
Canine ehrlichiosis is caused
by the bacteria Ehrlichia canis,
(transmitted by the brown
dog tick) and Ehrlichia ewingii
(transmitted by the lone star tick).
Canine Ehrlichia infections may
progress to the subclinical phase,
lasting days, months or years.
Did you know?
•The C6 peptide used in the IDEXX SNAP® 3Dx®, SNAP® 4Dx® Plus and
Lyme Quant C6® tests do not cross-react with the antibody response to
commercially available Lyme vaccines.1
•Dogs with seroreactivity to both B. burgdorferi and Anaplasma
phagocytophilum may have two times the risk of developing clinical illness
than singularly infected dogs.2
What to do with your SNAP® result
Borrelia burgdorferi
Anaplasma phagocytophilum
Primary vectors
Localizes in tissues of infected dogs
Positive result Infection is likely
WHAT
TO DO
NEXT?
Determine C6 antibody level with the Lyme Quant C6 Test
and evaluate for proteinuria (UPC)
Negative result
Infection is unlikely
•Review benefits
of tick prevention
•Retest in 1 year
Clinical presentation
Lyme disease is a chronic infection
with clinical signs that may present
acutely:
•Fever, anorexia, lethargy
•Polyarthritis, lameness
•Rapidly progressive renal failure
•Neurologic syndromes
Laboratory abnormalities
•Elevated (≥30 U/mL)
C6 antibody level
•Proteinuria
•Many mammalian species, including humans, are susceptible to
A. phagocytophilum infection.
•Coinfection of Anaplasma species with other vector-transmitted
pathogens may lead to more complex presentations and
slower response to therapy.
•A. platys infects canine platelets and is frequently seen as a
coinfection with Ehrlichia canis.
What to do with your SNAP® anaplasmosis and ehrlichiosis results
Anaplasma platys
Primary vectors
Ixodes scapularis
Ixodes pacificus
(deer tick or black-legged tick)
Pathology
Did you know?
Ixodes scapularis
Ixodes pacificus
(deer tick or black-legged tick)
Most likely Rhipicephalus sanguineus
(brown dog tick)
1
DIAGNOSE*
2
3
TREAT
MONITOR
4
PREVENT
Doxycycline/tetracycline
Retest C6 antibody level
with or without UPC
in 6 months to confirm
treatment success
Clinical signs and/or
laboratory findings
DO NOT support
Lyme disease
(C6 antibody level <30 U/mL)
Not generally recommended
Can present acutely:
•Fever
•Anorexia
•Lethargy
•Polyarthritis, lameness
•Neurologic signs
Infects platelets
Monitor for clinical signs
Discuss disease prevention strategies
Usually minimal clinical signs, but
some dogs may have:
•Fever
•Uveitis
•Petechia and ecchymoses
•Epistaxis
Laboratory abnormalities
• Thrombocytopenia
•Lymphopenia
•Increased liver enzymes
Positive result
The dog has been exposed
and may be infected
•Thrombocytopenia
Note
While not known to be chronic, experimental studies have shown
persistent infection.5,6
WHAT
TO DO
NEXT?
1
2
3
DIAGNOSE*
TREAT
MONITOR
4
PREVENT
*Serology is typically used to diagnose Lyme disease. B. burgdorferi localizes
to the tissues and is therefore rarely detectable in the blood by PCR.3
•Dogs coinfected with E. canis and A. platys were found to have more severe
anemia and thrombocytopenia than dogs with either single infection.6
•In a study of healthy dogs with antibodies to E. canis, 39% were
thrombocytopenic.7
•Chronic E. canis infections, if left untreated, can lead to
bone marrow dysfunction or renal disease.
Ehrlichia canis
Negative result
Exposure is unlikely
•Review benefits
of tick prevention
•Retest in 1 year
Rhipicephalus sanguineus
(brown dog tick)
Ehrlichia ewingii
Clinical signs and/or
laboratory findings
DO support
anaplasmosis/ehrlichiosis
Infects granulocytes
Clinical signs and/or
laboratory findings
DO NOT support
anaplasmosis/ehrlichiosis
• Fever, anorexia, lethargy
•Fever, anorexia, lethargy
• Bleeding disorders
•Polyarthropathy, lameness
• Polyarthritis, lameness
•Neurological signs
• Lymphadenomegaly
Not generally recommended
Discuss disease prevention strategies
*Additional diagnostics may include PCR or IFA titer. See
the Diagnostics for Sick Patients section of this guide for
more information on serological and PCR testing.
•For more information and current recommendations on treating canine
heartworm disease, go to heartwormsociety.org or capcvet.org.
What to do with your SNAP® result
Mosquito
Positive result
• Thrombocytopenia
Infective larvae (L3) mature to adult
worms in the heart and pulmonary
arteries
WHAT
TO DO
NEXT?
• Confirm with retest
• Evaluate for microfilaria
Clinical signs DO support
heartworm disease
No clinical signs
1
• Radiographs
• CBC/Chemistry profile
• Other tests as appropriate
• Confirm with retest
• Evaluate for microfilaria*
• CBC/chemistry profile
• Other tests as
appropriate
Infection unlikely
2
According to
American Heartworm
Society (AHS) guidelines
Treatment depends on
supplemental test results
Heartworm prevention
Retest in 6–12 months
• Assess heartworm
antigen status
• Assess cardiopulmonary
disease
If no definitive diagnosis,
repeat diagnostics in
1–3 months
Retest in 12 months
Clinical presentation
Asymptomatic at first, later
developing:
•Mild, persistent cough
•Weight loss
Laboratory Abnormalities
•Hyperglobulinemia •Eosinophilia
•Azotemia
•Increased liver enzymes
Not known to be chronic, but
experimental studies have shown
persistent infection.8
Negative result
Pathology
•Reduced appetite
•Thrombocytopenia
Note
Recheck CBC at wellness exams
•Despite availability of monthly preventives, prevalence rates of canine
heartworm has remained consistent nationwide.4
DIAGNOSE
•Exercise intolerance
Laboratory abnormalities
• Proteinuria
Evaluate platelet count in 1 week;
if no improvement, pursue other
diagnoses
Did you know?
Dirofilaria immitis
•Lethargy
• Neurological signs
•Anemia Doxycycline/tetracycline
Amblyomma americanum
(lone star tick)
Clinical presentation
Check for hematologic abnormalities
(CBC and/or blood film) and changes
in serum proteins
Dirofilaria immitis, the causative
agent of heartworm disease,
is transmitted by infected
mosquitoes when D. immitis
larvae are transferred to a healthy
dog. Heartworm disease has
no obvious clinical signs in the
early stages, making preventive
measures so much more
important—especially as advanced
infection may result in death.
Primary vector
Pathology
Infects monocytes
Clinical presentation
Clinical signs and/or
laboratory findings
DO support Lyme disease
(C6 antibody level ≥30 U/mL)
Did you know?
Primary vector
Pathology
Infects neutrophils
Heartworm disease
•Proteinuria
TREAT
3
MONITOR
4
PREVENT
Follow AHS/CAPC guidelines on heartworm prevention
*Less than 1% of infections will have microfilariae but not
be antigenemic (source: American Heartworm Society).
Annual screening with
the SNAP® 4Dx® Plus Test
Diagnostics for sick patients
Serology and PCR testing options—For a sick dog presenting with clinical signs consistent with a vectorborne disease, it’s important to consider both serology and PCR testing because they are complementary.
Screen your canine patients every year with the SNAP® 4Dx® Plus Test to detect exposure to
pathogens that cause heartworm disease, ehrlichiosis, Lyme disease and anaplasmosis.
Positive result
The dog has been exposed and may be infected
WHAT
TO DO
NEXT?
Perform additional tests to confirm infection
Clinical signs and/or laboratory findings indicate either:
Self-limiting infection
No clinical signs or laboratory abnormalities
1
DIAGNOSE
2
3
4
TREAT
MONITOR
PREVENT
Subclinical infection
Apparently healthy dogs with laboratory abnormalities
Clinical disease
Infected dogs with clinical signs
with or without laboratory abnormalities
If necessary
Retest in 6–12 months
Quick tips to share with
pet owners
Negative result
Exposure unlikely
•Review benefits
of prevention
– preventive
– vaccination
•Retest in 1 year
Depending on
the results of a
pet’s screening,
additional testing
or therapies may
be required.
Benefits and limitations of each diagnostic method:
Polymerase chain reaction (PCR)
Measures
Antibody response of host
Nucleic acid (DNA) from pathogen
Benefits
Useful for screening as well
as diagnosis of infection
Specifically identifies pathogens
indicating active infection
Clinical signs may precede
a measurable antibody
response
A negative PCR result does not
necessarily rule out infection
•Use a tick preventive on your dog.
Limitations
•Watch your dog closely for
changes in behavior or appetite
and call your veterinarian with
any concerns.
•Talk with your veterinarian about
ticks and vector-borne disease
in your area.
•If your pet’s test results are
negative, congratulations! Keep
up the good work with regular
preventive screenings and daily
tick checks.
When to use the IDEXX RealPCR™
vector-borne disease panels:
Serology
•Check your dog for ticks daily.
If you find a tick, remove it right
away (ticks will gravitate to the
head, ears and neck).
Dogs with ehrlichiosis and anaplasmosis may present with clinical signs
at different times after infection. Which sick dog are you dealing with?
Using serology and
PCR together improves
your ability to make a
complete and accurate
diagnosis.
Positive result
A pet’s screening result
and what it means
PCR
Go to dogsandticks.com
for more information.
Dog A
presents
Dog B
presents
•Patients with subclinical infections
based on history, physical exam,
serology and clinical laboratory
findings
•Monitoring response to therapy—
the Lyme Quant C6® Test can
indicate waning antibody levels,
and for other pathogens, a negative
PCR result indicates a reduction in
pathogen load
No single test is sufficient for
•
•
diagnosing an infectious disease
in a sick patient.••
Serology
Time postinfection
Infection or
Recrudescence
•Sick patients with clinical signs
and/or laboratory abnormalities
consistent with a vector-borne illness
Dog C
presents
Edward Breitschwerdt, DVM, DACVIM*
Professor, Internal Medicine
College of Veterinary Medicine,
North Carolina State University
Discuss disease prevention strategies
*Dr. Breitschwerdt has a business relationship with IDEXX pursuant to which he
receives compensation from IDEXX from time to time. The views expressed in this
brochure are solely those of Dr. Breitschwerdt.
1.O’Connor TP, Esty KJ, Hanscom JL, Shields P, Philipp MT. Dogs vaccinated with common
Lyme disease vaccines do not respond to IR6, the conserved immunodominant region of the
VlsE surface protein of Borrelia burgdorferi. Clin Diagn Lab Immunol. 2004;11(3):458–462.
6.Gaunt S, Beall M, Stillman B, et al. Experimental infection and co-infection of dogs with
Anaplasma platys and Ehrlichia canis: hematologic, serologic and molecular findings.
Parasit Vectors. 2010;3(1):33.
2.Beall MJ, Chandrashekar R, Eberts MD, et al. Serological and molecular prevalence of
Borrelia burgdorferi, Anaplasma phagocytophilum, and Ehrlichia species in dogs from
Minnesota. Vector-Borne Zoonotic Dis. 2008;8(4):455–464.
7.Hegarty BC, Diniz PPVP, Bradley JM, Lorentzen L, Breitschwerdt EB. Clinical relevance of
annual screening using a commercial enzyme-linked immunosorbent assay (SNAP 3Dx)
for canine ehrlichiosis. JAAHA. 2009;45(3):118–124.
3. S
traubinger RK. PCR-based quantification of Borrelia burgdorferi organisms in canine tissues
over a 500-day postinfection period. J Clin Microbiol. 2000;38(6):2191–2199.
8.Yabsley MJ, Adams DS, O’Connor TP, Chandrashekar R, Little SE. Experimental
primary and secondary infections of domestic dogs with Ehrlichia ewingii. Vet Microbiol.
2011;105(3-4):315–321.
4.Verdon DR. Heartworm infection continues its climb, survey reports. DVM Newsmagazine.
February 1, 2006.
5.Egenvall A, Lilliehöök I, Bjöersdorff A, Engvall EO, Karlstam E, Artursson K, Heldtander
M, Gunnarsson A. Detection of granulocytic Ehrlichia species DNA by PCR in persistently
infected dogs. Vet Rec. 2000;146(7):186–190.
Black-legged tick (Ixodes scapularis), lone star tick (Amblyomma americanum) and brown dog tick (Rhipicephalus
sanguineus) images supplied by the Armed Forces Pest Management Board. afpmb.org. Photographer: James L. Occi.
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