STEPs—Simple Tools for Effective Protocols
Vector-borne Disease Screening
Protocol Implementation
Suggested vector-borne disease screening guidelines
SNAP® 4Dx® Test Screen your dog every year with the SNAP 4Dx Test to detect exposure to pathogens that cause heartworm disease, ehrlichiosis, Lyme disease and anaplasmosis.
Your pet’s screening result and what it means Depending on the results of your pet’s wellness screening, additional testing or therapies may be required.
Positive result The dog has been exposed and may be infected
? What to
Run additional tests to confirm infection
do next?
Clinical signs and/or laboratory findings indicate either
1 Diagnose
2 Treat
Self-limiting infection Dogs that have likely resolved their infection
Subclinical infection Infected dogs without any apparent signs of illness
Clinical disease Infected dogs with clinical signs that are recognizable
If necessary
3 Monitor
Retest in 1 year
4 Prevent
Discuss disease prevention strategies
Negative result Exposure unlikely
• Review benefits of prevention – preventives – vaccination • Retest in 1 year
STEPs—Simple Tools for Effective Protocols
Vector-borne Disease Screening
Protocol Implementation
page 2
Suggested Lyme Disease Screening Guidelines 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. Did you know? The C6 peptide used in the IDEXX SNAP® 3Dx®, SNAP® 4Dx®/and Lyme Quant C6® tests do not cross-react with antibody response to commercially available Lyme vaccines.1 Ixodes ticks are known to be vectors for both Lyme disease and anaplasmosis. ogs with seroreactivity to both B. burgdorferi and Anaplasma phagocytophilum D may have two times the risk of developing clinical illness than singularly infected dogs.2
do next?
Positive result Infection is likely
Negative result Infection is unlikely
Determine antibody level with the Lyme Quant C6 Test and evaluate for proteinuria (UPC)
Review benefits of tick prevention
Clinical signs and/or laboratory findings DO support Lyme disease (C6 antibody level ≥30 U/mL)
Clinical signs and/or laboratory findings DO NOT support Lyme disease (C6 antibody level <30 U/mL)
2 Treat
Doxycycline/tetracycline
Not generally recommended
3 Monitor
Retest C6 antibody level with or without UPC in 6 months to confirm treatment success
Monitor for clinical signs
1 Diagnose*
4 Prevent
Primary vector Ixodes spp. (deer tick or black-legged tick) Transmission 24–48 hours of tick attachment Pathogen Borrelia burgdorferi spirochete, which localizes in tissues of infected dogs
What to do with your result
? What to
Medical background
Discuss disease prevention strategies
Clinical presentation Lyme is a chronic infection with clinical signs that may present acutely: • Fever, anorexia, lethargy • Joint swelling • Polyarthritis • Shifting leg lameness • Rapidly progressive renal failure • Neurologic syndromes Laboratory abnormalities • Elevated (≥30 U/mL) C6 antibody level • Proteinuria
* 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
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. 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. 3. Straubinger 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.
STEPs—Simple Tools for Effective Protocols
Vector-borne Disease Screening
Protocol Implementation
page 3
Suggested Canine Anaplasmosis Screening Guidelines Canine granulocytic anaplasmosis is caused by the bacterium Anaplasma phagocytophilum and is transmitted by the deer tick or black-legged tick. A. phagocytophilum is an obligate intracellular pathogen of neutrophils. Many mammalian species, including humans, are susceptible to infection. Did you know? Coinfection of Anaplasma species with other vector-transmitted pathogens may lead to more complex disease presentations and a slower response to therapy Anaplasma platys is the cause of infectious cyclic thrombocytopenia in dogs, and antibodies to this pathogen cross-react with the A. phagocytophilum spot on the SNAP 4Dx Test A. platys infects canine platelets and is frequently seen as a coinfection with Ehrlichia canis What to do with your result
? What to
do next?
1 Diagnose*
2 Treat
3 Monitor
4 Prevent
Positive result The dog has been exposed and may be infected
Negative result Exposure is unlikely
Check for hematologic abnormalities (CBC and/or blood film)
Review benefits of tick prevention
Clinical signs and/or laboratory findings DO support anaplasmosis
Clinical signs and/or laboratory findings DO NOT support anaplasmosis
Doxycycline/tetracycline
Not generally recommended
Evaluate platelet count in 1 week; if no improvement, pursue other diagnoses
Recheck CBC at wellness exams
Discuss disease prevention strategies
Medical background Primary vector Ixodes spp. (deer tick or black-legged tick) Transmission <24 hours of tick attachment Pathogen Anaplasma phagocytophilum infects canine neutrophils Clinical presentation Can present acutely: • Fever, anorexia, lethargy • Joint pain and swelling • Lameness • Neurologic signs Laboratory abnormalities • Thrombocytopenia • Lymphopenia • Increased liver enzymes
* Additional diagnostics may include PCR or Anaplasma IFA titer. See the Diagnostics for Sick Patients section of this guide for more information on serological and PCR testing.
Note Not known to be chronic, but experimental studies have shown persistent infection.4
4. 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.
STEPs—Simple Tools for Effective Protocols
Vector-borne Disease Screening
Protocol Implementation
page 4
Suggested Canine Ehrlichiosis Screening Guidelines Canine ehrlichiosis is caused by the bacterium Ehrlichia canis and is transmitted by the brown dog tick. The infection may progress to a subclinical phase, which can last days, months or years. Chronic infections, if left untreated, can lead to bone marrow dysfunction or renal disease. Did you know? Dogs coinfected with E. canis and A. platys were found to have more severe anemia and thrombocytopenia than dogs with either single infection.5 E. canis, and likely A. platys, are transmitted by the same vector, the brown dog tick. In a study of healthy dogs with antibodies to E. canis, 39% were thrombocytopenic.6
What to do with your result
? What to
do next?
1 Diagnose*
2 Treat
3 Monitor
4 Prevent
Positive result The dog has been exposed and may be infected
Negative result Exposure is unlikely
Check for hematologic abnormalities (CBC and/or blood film) and changes in serum proteins
Review benefits of tick prevention
Clinical signs and/or laboratory findings DO support ehrlichiosis
Clinical signs and/or laboratory findings DO NOT support ehrlichiosis
Doxycycline/tetracycline
Not generally recommended
Evaluate platelet count in 1 week; if no improvement, pursue other diagnoses
Recheck CBC at wellness exams
Discuss disease prevention strategies
Medical Background Primary vector Rhipicephalus sanguineus (brown dog tick) Transmission Time needed for transmission is unknown Pathogen Ehrlichia canis infects canine monocytes Clinical presentation Can present acutely: • Fever • Anorexia • Lethargy • Uveitis • Lymphadenomegaly • Bleeding disorders • CNS signs Has a chronic nature: • Weight loss • Bleeding disorders • Polyarthritis • Seizures • Multisystemic signs
* Additional diagnostics may include PCR or Ehrlichia IFA titer. See the Diagnostics for Sick Patients section of this guide for more information on serological and PCR testing.
5. Gaunt SD, Ramaswamy C, Beall M, Caterina K, Breitschwerdt E. Potentiation of thrombocytopenia and anemia in dogs experimentally coinfected with Anaplasma platys and Ehrlichia canis. JVIM. 2007;21(3):576. 6. 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.
Laboratory abnormalities • Anemia • Thrombocytopenia • Hyperglobulinemia • Hypoalbuminemia • Pancytopenia • Proteinuria
STEPs—Simple Tools for Effective Protocols
Vector-borne Disease Screening
Protocol Implementation
page 5
Suggested Heartworm Screening Guidelines Dirofilaria immitis, the causative agent of heartworm disease, is transmitted by infected mosquitoes when D. immitis larvae are transferred to a healthy dog. Heartworm has no obvious clinical signs in the early stages, making preventative measures so much more important—especially as advanced infection may result in death. Did you know?
Medical background
espite availability of monthly preventatives, prevalence rates of canine heartworm D has remained consistent nationwide.7
Primary vector Mosquitoes
The earliest heartworm antigen and microfilariae can be detected postinfection is 5 months and 6.5 months, respectively. For more information and current recommendations on treating canine heartworm disease, go to heartwormsociety.org or capcvet.org.
Pathogen Dirofilaria immitis
What to do with your result Canine heartworm testing
No clinical signs
HW Ag NEGATIVE
No action required
Follow-up Refer to the American Heartworm Society (AHS)/Companion Animal Parasite Council (CAPC) guidelines on chemoprophylaxis
Transmission Prepatent period approximately 6 months
Clinical signs
HW Ag POSITIVE
• Confirm with retest • Radiographs (assess cardiopulmonary disease) • CBC, chemistry and/or other appropriate tests
Treatment/Follow-up • Treat according to the American Heartworm Society guidelines • Retest 6 –12 months assessing for: -C onversion to Ag negative status - I mprovement of cardiopulmonary disease
HW Ag NEGATIVE
• Modified Knott’s testing for microfilariae* • Radiographs • CBC, chemistry and/or other appropriate tests • Consider other differential diagnoses If no definitive diagnosis, repeat in 1–3 months
Treatment/Follow-up Dependent upon supplementary test results * Less than 1% of infections will have microfilariae but not be antigenemic (American Heartworm Society)
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Clinical presentation Asymptomatic at first, later developing: • Mild, persistent cough • Lethargy • Exercise intolerance • Reduced appetite • Weight loss
7. Verdon DR. Heartworm infection continues its climb, survey reports. DVM Newsmagazine. February 1, 2006.