Antibody Titer Testing in Dogs: Evaluation of Three Point-of-Care Tests for Canine Core Vaccine Antigens Compared to Virus Neutralization

Antibody titer testing can be useful in controlling successful puppy immunization and can reduce unnecessary vaccinations in adult dogs. We evaluated three commercially available point-of-care tests (POCTs) for detecting antibodies against canine parvovirus (CPV-2), canine distemper virus (CDV) and canine adenovirus (CAV-1 and/or -2), comparing them to the reference virus neutralization (VN) assay. Sera from 200 client-owned dogs (13 healthy, 63 chronically diseased, 124 acute) and 60 specific pathogen-free (SPF) dogs, including 20 sera with maternally derived antibodies (MDA), were tested. All three POCTs demonstrated high sensitivity (79.0–100%) and specificity (97.8–100%) for CPV-2. In contrast, specificity for CDV and CAV was lower with POCT-1 (43.5% and 55.3%) and POCT-2 (42.4% and 79.2%), despite high sensitivity (CDV in both POCTs 98.7%; CAV POCT-1: 99.4%, POCT-2: 90.8%). POCT-3, by comparison, showed high specificity (CDV: 94.1%; CAV: 84.4%) but very low sensitivity (CDV: 17.4%; CAV: 33.1%). Only POCT-1 for CPV-2 detected MDA reliably, whereas the other two POCTs, and POCT-1 for CDV and CAV, did not. When compared to VN, the agreement in vaccination recommendations was 82% for POCT-1 and POCT-2, and 62% for POCT-3. In conclusion, all three POCTs reliably detected antibodies against CPV-2, including MDA with POCT-1. However, the lower specificity for CDV and CAV antibody detection in POCT-1 and POCT-2 raises concerns about misclassifying unprotected dogs as immune, while false-negatives with POCT-3 could lead to unnecessary vaccinations. Further optimization of all three POCTs for CDV and CAV is recommended.