Evaluation of Ante-Mortem Sampling Matrices for qPCR Detection of Canine Distemper Virus

Canine distemper virus (CDV) is a multi-host morbillivirus of domestic dogs and wild carnivores, and early molecular detection is important for treatment, isolation, and wildlife surveillance. However, the most informative ante-mortem specimen type for RT-qPCR screening remains context dependent. This pilot study compared CDV RNA detection and viral load across paired sample matrices from nine dogs and screened archived blood/serum samples from four tigers and one clouded leopard. CDV RNA was extracted using a commercial viral nucleic-acid kit and amplified using a one-step RT-qPCR assay. Five of nine dogs were CDV-positive. Among positive dogs, conjunctival swabs detected CDV RNA in 5/5 animals (100%), followed by nasal swabs (4/5), rectal swabs (3/5), whole blood (2/5), and urine (1/5). Viral load ranged from 9.55 to 213,796.21 RNA copies/μL. Exact Cochran’s Q and Friedman tests did not reach statistical significance, but Kendall’s W suggested a moderate sample-type effect. These results support conjunctival swabs as the most consistent specimen in this dataset, with nasal and rectal swabs as useful complementary matrices.