Performance of a commercially available in-clinic ELISA for detection of antibodies against Anaplasma phagocytophilum, Anaplasma platys, Borrelia burgdorferi, Ehrlichia canis, and Ehrlichia ewingii and Dirofilaria immitis antigen in dogs

Objective-To evaluate the performance of an in-clinic ELISA designed for detection of heartworm antigen and antibodies against 5 tick-borne pathogens. Design-Validation study. Sample-1,601 serum or matched serum, plasma, and blood samples from dogs. Procedures-Samples were tested for Dirofilaria immitis (heartworm) antigen and antibodies against Anaplasma phagocytophilum, Anaplasma platys, Borrelia burgdorferi, Ehrlichia canis, and Ehrlichia ewingii by means of an in-clinic ELISA. Evaluation of assay sensitivity and specificity, agreement of results among sample types, and cross-reactivity of E canis antigens in the assay with anti-Ehrlichia chaffeensis antibodies in stored samples from experimentally infected dogs were performed at a reference laboratory. Field tests of the in-clinic ELISA were performed at 6 veterinary facilities. Results were compared with confirmatory test results. Results-Sensitivity and specificity of the in-clinic ELISA were > 89% for detection of antibodies against A phagocytophilum (93.2% and 99.2%, respectively), A platys (89.2% and 99.2%, respectively), B burgdorferi (96.7% and 98.8%, respectively), E canis (97.8% and 92.3%, respectively), and E ewingii (96.5% and 93.9%, respectively). Sensitivity of the assay for detection of D immitis was 98.9%, with 99.3% specificity. The in-clinic ELISA identified exposure to > 1 vector-borne pathogen in 354 of 1,195 samples. Cross-reactivity of E canis antigens with anti-E chaffeensis antibodies was confirmed. Results of field evaluations confirmed that the in-clinic ELISA could be reliably used under typical clinical conditions to identify dogs exposed to the pathogens of interest. Conclusions and Clinical Relevance-The in-clinic ELISA provided a comprehensive in-house serologic screening test for all vector-borne pathogens evaluated.