Silicon surface multiplex immunoassay (Accuplex) for antibodies against Anaplasma spp and Ehrlichia spp is a robust option for tick-borne pathogen screening in dogs

Objective: To evaluate the diagnostic performance of a point-of-care (POC) test (SNAP 4Dx Plus; Idexx Laboratories Inc) versus a proprietary silicon surface multiplex immunoassay (SSMIA) test (Accuplex; Antech Diagnostics Inc) with indirect fluorescent antibody as the reference method (REFERENCE) for detecting antibodies against Anaplasma spp and Ehrlichia spp in dogs and to compare SSMIA test results with period prevalences reported by the Companion Animal Parasite Council (CAPC). Methods: Anonymized retention-released serum samples from dogs in the US submitted to a commercial laboratory between July 1, 2023, and September 30, 2024, were classified as true positive or true negative for each antibody via REFERENCE. Performance metrics (sensitivity, specificity, and Cohen κ) were calculated (REFERENCE as the standard) for SSMIA versus POC. Additional separate serum samples from dogs in Connecticut, Massachusetts, New Jersey, New York, and Pennsylvania underwent SSMIA testing alone in July 2024, and results were compared with respective period prevalence data reported by the CAPC. Results: Test methods did not differ significantly for detection of antibodies against Anaplasma spp (n = 310 samples). Silicon surface multiplex immunoassay was significantly more sensitive than POC for Ehrlichia spp antibody detection (n = 309 samples). Another 2,031 samples underwent SSMIA testing alone, and positivity rates were generally higher for SSMIA detection as compared to CAPC reporting. Conclusions: These findings support SSMIA as a robust option for routine tick-borne pathogen exposure screening in dogs. Clinical Relevance: Our work provides veterinarians with field and comparative performance data on 2 commercially available tests, informing evidence-based contextualized diagnostic options.