Annual Screening for Vector-borne Disease The SNAP Dx Plus Test Clinical Reference Guide
Every dog, every year 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. Know more with every result With the SNAP Dx Plus Test, a positive result can also be an indication of ticks and other pathogens in your area. Your patients Educating pet owners about the risk of vector-borne disease is an opportunity to stress the importance of screening and prevention. Your community Comprehensive annual screenings give you a current snapshot of how widespread certain diseases and tick species are in the area. Your practice 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 Dx Plus Test as a screening tool, you may detect antibodies to these pathogens Ehrlichia ewingii carried by these ticks Lone star tick Amblyomma americanum that may also transmit other infections to dogs and people Ehrlichia chaffeensis Tularemia STARI Geographic tick distribution as of 20 Anaplasma phagocytophilum Borrelia burgdorferi (Lyme disease) Deer tick or black-legged tick Bartonella spp. Babesia spp. Anaplasma platys Brown dog tick Rhipicephalus sanguineus Babesia spp. American dog tick Dermacentor variabilis Tularemia
Lyme disease Canine anaplasmosis Canine ehrlichiosis Heartworm disease 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. The C 6 peptide used in the IDEXX SNAP Dx, SNAP Dx Plus and Lyme Quant C 6 tests do not cross-react with the antibody response to commercially available Lyme vaccines. 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 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. 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. Canine ehrlichiosis is caused by the bacteria, (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. 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, 9% were thrombocytopenic. 7 Chronic E. canis infections, if left untreated, can lead to bone marrow dysfunction or renal disease. 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. Despite availability of monthly preventives, prevalence rates of canine heartworm has remained consistent nationwide. For more information and current recommendations on treating canine heartworm disease, go to heartwormsociety.org or capcvet.org. Borrelia burgdorferi What to do with your SNAP result Anaplasma phagocytophilum Anaplasma platys What to do with your SNAP anaplasmosis and ehrlichiosis results Ehrlichia ewingii Dirofilaria immitis What to do with your SNAP result Primary vectors (deer tick or black-legged tick) Localizes in tissues of infected dogs Lyme disease is a chronic infection with clinical signs that may present acutely: Rapidly progressive renal failure Neurologic syndromes Elevated ( 0 U/mL) C 6 antibody level DIAGNOSE* DO support Lyme disease (C 6 antibody level 0 U/mL) Doxycycline/tetracycline Retest C 6 antibody level with or without UPC in 6 months to confirm treatment success Infection is likely Determine C 6 antibody level with the Lyme Quant C 6 Test and evaluate for proteinuria (UPC) DO NOT support Lyme disease (C 6 antibody level <0 U/mL) Not generally recommended Monitor for clinical signs * Serology is typically used to diagnose Lyme disease. B. burgdorferi localizes to the tissues and is therefore rarely detectable in the blood by PCR. Infection is unlikely of tick prevention Retest in year Primary vectors (deer tick or black-legged tick) Infects neutrophils Can present acutely: Fever Anorexia Lethargy Neurologic signs Lymphopenia Increased liver enzymes Note Most likely Rhipicephalus sanguineus (brown dog tick) Infects platelets Usually minimal clinical signs, but some dogs may have: Fever Uveitis Petechia and ecchymoses Epistaxis While not known to be chronic, experimental studies have shown persistent infection. 5,6 DIAGNOSE* The dog has been exposed and may be infected Check for hematologic abnormalities (CBC and/or blood film) and changes in serum proteins DO support anaplasmosis/ehrlichiosis Doxycycline/tetracycline Evaluate platelet count in week; if no improvement, pursue other diagnoses Exposure is unlikely DO NOT support anaplasmosis/ehrlichiosis Not generally recommended Recheck CBC at wellness exams of tick prevention Retest in year * 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. Primary vector Rhipicephalus sanguineus (brown dog tick) Infects monocytes Bleeding disorders Lymphadenomegaly Neurological signs Anemia Hyperglobulinemia Note Amblyomma americanum (lone star tick) Infects granulocytes Polyarthropathy, lameness Neurological signs Not known to be chronic, but experimental studies have shown persistent infection. 8 Primary vector Mosquito Infective larvae (L) mature to adult worms in the heart and pulmonary arteries Asymptomatic at first, later developing: Mild, persistent cough Lethargy Exercise intolerance Reduced appetite Weight loss Laboratory Abnormalities Eosinophilia Azotemia Increased liver enzymes DIAGNOSE Confirm with retest Evaluate for microfilaria Radiographs CBC/Chemistry profile Other tests as appropriate According to American Heartworm Society (AHS) guidelines Retest in 6 2 months Assess heartworm antigen status Assess cardiopulmonary disease Clinical signs DO support heartworm disease Confirm with retest Evaluate for microfilaria* CBC/chemistry profile Other tests as appropriate Treatment depends on supplemental test results If no definitive diagnosis, repeat diagnostics in months Follow AHS/CAPC guidelines on heartworm prevention * Less than % of infections will have microfilariae but not be antigenemic (source: American Heartworm Society). No clinical signs Infection unlikely Heartworm prevention Retest in 2 months
Annual screening with the SNAP Dx Plus Test Screen your canine patients every year with the SNAP Dx Plus Test to detect exposure to pathogens that cause heartworm disease, ehrlichiosis, Lyme disease and anaplasmosis. 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. DIAGNOSE 2 TREAT A pet s screening result and what it means The dog has been exposed and may be infected Perform additional tests to confirm infection indicate either: Self-limiting infection No clinical signs or laboratory abnormalities 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 2 months Exposure unlikely of prevention preventive vaccination Retest in year Depending on the results of a pet s screening, additional testing or therapies may be required. Quick tips to share with pet owners Check your dog for ticks daily. If you find a tick, remove it right away (ticks will gravitate to the head, ears and neck). Use a tick preventive on your dog. 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. Go to dogsandticks.com for more information. Benefits and limitations of each diagnostic method: Serology Polymerase chain reaction (PCR) Measures Antibody response of host Nucleic acid (DNA) from pathogen Benefits Limitations Useful for screening as well as diagnosis of infection Clinical signs may precede a measurable antibody response Specifically identifies pathogens indicating active infection A negative PCR result does not necessarily rule out infection 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. Infection or Recrudescence PCR Dog A Dog B Serology Time postinfection Dog C When to use the IDEXX RealPCR vector-borne disease panels: Sick patients with clinical signs and/or laboratory abnormalities consistent with a vector-borne illness Patients with subclinical infections based on history, physical exam, serology and clinical laboratory findings Monitoring response to therapy the Lyme Quant C 6 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. Edward Breitschwerdt, DVM, DACVIM* Professor, Internal Medicine College of Veterinary Medicine, North Carolina State University * 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.
. O Connor TP, Esty KJ, Hanscom JL, Shields P, Philipp MT. Dogs vaccinated with common Lyme disease vaccines do not respond to IR 6, the conserved immunodominant region of the VlsE surface protein of Borrelia burgdorferi. Clin Diagn Lab Immunol. 200;():58 62. 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():55 6.. Straubinger RK. PCR-based quantification of Borrelia burgdorferi organisms in canine tissues over a 500-day postinfection period. J Clin Microbiol. 2000;8(6):29 299.. Verdon DR. Heartworm infection continues its climb, survey reports. DVM Newsmagazine. February, 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;6(7):86 90. 6. Gaunt S, Beall M, Stillman B, et al. Experimental infection and co-infection of dogs with Anaplasma platys and : hematologic, serologic and molecular findings. Parasit Vectors. 200;():. 7. Hegarty BC, Diniz PPVP, Bradley JM, Lorentzen L, Breitschwerdt EB. Clinical relevance of annual screening using a commercial enzyme-linked immunosorbent assay (SNAP Dx) for canine ehrlichiosis. JAAHA. 2009;5():8 2. 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. 20;05(-):5 2. Black-legged tick (), 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. 20 IDEXX Laboratories, Inc. All rights reserved. 09-6907-02 All /TM marks are owned by IDEXX Laboratories, Inc. or its affiliates in the United States and/or other countries. The IDEXX Privacy Policy is available at idexx.com.