Comparison of three rapid commercial Canine parvovirus antigen detection tests with electron microscopy and polymerase chain reaction.

Different antibody-based tests for rapid detection of Canine parvovirus antigens in feces are commercially available, allowing quick diagnosis in a clinical setting. However, the diagnostic accuracy of these tests compared with standard methods has not been evaluated so far. In the current study, 3 commercial tests were compared with immune-electron microscopy (IEM) and polymerase chain reaction (PCR). Dogs were divided into 3 groups: group A, samples from dogs with acute hemorrhagic diarrhea (n = 50); group B, dogs with chronic diarrhea (n = 10); and group C, dogs with no evidence of gastrointestinal disease (n = 40). Specificity of all 3 commercial tests versus PCR and IEM was good to excellent (92.2-100%). Sensitivity, in contrast, was poor: 15.8-26.3% versus PCR and 50-60% versus IEM. In group A, 10 dogs were positive by IEM and 24 dogs were positive by PCR. Positive PCR results were also obtained from animals in control groups (group B, 1 dog; group C, 5 dogs). No dog in group B or C was positive by IEM. In conclusion, the rapid tests are useful to diagnose canine parvoviral enteritis, but they do not rule out parvovirus infection in an animal with typical clinical signs. In addition, a small percentage of healthy dogs and dogs with chronic diarrhea showed positive PCR results; this may be due to asymptomatic/persistent infection or intestinal passage of virus. The significance of this finding remains unclear.