Abstract: Background– The Companion Animal Parasite Council predicts continued range expansion of United States (US) and Canadian tick vectors. Effective surveillance for tick-transmitted pathogens in dogs, such as Ehrlichia spp. (E. canis, E. chaffeensis, and E. ewingii), is needed. Detection of antibodies (serology) can be an accurate method to test for canine pathogen exposure in the US and Canada. Objectives– To analyze performance of a proprietary silicon surface multiplex immunoassay (SSMIA) using two combined novel markers to detect Ehrlichia spp. antibodies (Accuplex®, Antech Diagnostics, Mars Petcare Science & Diagnostics) in canine serum samples compared to indirect fluorescent antibody (IFA) and a commercially available point-of-care ELISA (IDEXX 4Dx® Plus-POC-ELISA). Animals– Anonymized retention-released serum samples from dogs in the Southeastern US submitted to a commercial reference laboratory. Methods– Samples were evaluated by SSMIA, IFA, and POC-ELISA. IFA was used to classify samples (true positive/true negative). SSMIA was evaluated compared to IFA prioritizing specificity [with 95% confidence interval (95%CI)] and kappa statistics (95%CI) for agreement comparing SSMIA and POC-ELISA to IFA. Anaplasma spp. antibody detected samples were excluded due to potential IFA cross-reactivity. Results– For 309 evaluable samples, SSMIA (2 markers combined) compared to IFA yielded a 94% sensitivity (95%CI: 86-97%), 97% specificity (95%CI: 95-99%), and kappa of 0.9 (95%CI: 0.84-0.95) and 0.67 (95%CI: 0.57-0.77) for SSMIA and POC-ELISA compared to IFA, respectively. Clinical importance– This study demonstrates SSMIA is an effective and accurate tool for Ehrlichia spp. exposure detection in dogs, and compares favorably to other commercially available products.
