Chapter 130 The most clinically useful method of detection of virus in the ill animal is via point-of-care enzyme-linked immunosorbent assays (ELISAs). These assays detect viral antigen in feces or rectal swabs and results are relatively sensitive and specific; however, false negatives and false positives can occur. False negatives can occur with infection of any CPV-2 variant secondary to relatively low concentrations of viral particles because of either decreased shedding in the later stages of the disease or dilutional effects from voluminous diarrhea. The impact of infection with CPV-2c on point-of-care ELISA results is controversial at this time. There are reports of CPV-2c causing clinical disease but negative point-of-care ELISA results. However, other studies have demonstrated similar results using such assays for CPV-2c as for CPV-2a and -2b (Decaro et al, 2010). Preliminary work in the author’s laboratory has identified three animals in a series of 49 dogs with a clinical diagnosis in which CPV was not detected in feces using point-of-care ELISAs, but CPV was detected using quantitative polymerase chain reaction (PCR). All three of these isolates were later determined to be the CPV-2c variant (Veir, unpublished data). However, because a complete history and clinical illness were not available for all of these animals, the same reasons for any false negative may be the cause. In another study, there was no statistical difference in the sensitivity of a point-of-care ELISA for detection of CPV-2b and CPV-2c (Markovich et al, 2012). False positives have been reported in association with recent vaccination with modified live parvoviral diseases. One manufacturer of point-of-care assays has an unpublished study demonstrating lack of reaction after vaccination in a group of 60 beagles vaccinated with modified live parvoviral vaccines (MLV). In a study performed in the author’s laboratory of 12 puppies vaccinated with a MLV parvoviral vaccine, feces from one puppy produced a positive result on a point-of-care ELISA 5 days after vaccination (Burton et al, 2008).
Canine Parvoviral Enteritis
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Canine Parvoviral Enteritis
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