TABLE 14-3.

Diagnostic Assays Available for Canine Parvoviral Enteritis in Dogs

Assay	Specimen type	Target	Performance
Fecal antigen ELISA	Feces	CPV antigen	Specificity for detection of virus nears 100%, but weak false positives have the potential to occur after immunization with attenuated live vaccines. False negatives are common (low sensitivity).
Hemagglutination assay	Feces	CPV antigen	Inexpensive and rapid. Sensitivity and specificity in naturally infected dogs has not been well established.
Histopathology	Usually necropsy specimens, especially gastrointestinal tissues	Crypt necrosis with intranuclear inclusions; parvovirus antigen with IHC or parvovirus DNA with in situ hybridization	Can be used for diagnosis at necropsy. In situ hybridization may be most sensitive for detection of virus in tissues.
Polymerase chain reaction (PCR)	Feces, tissue species	CPV DNA	Sensitivity and specificity may vary depending on assay design. Attenuated live vaccine virus may be detected in feces for days to weeks after vaccination, but some assays differentiate between vaccine and field virus. Because of the high sensitivity of some assays, the significance of a positive result may be difficult to interpret. False negative results may occur as a result of inhibition of PCR by components of feces. Degradation of nucleic acid during specimen transport is more problematic for RNA viruses such as canine coronavirus.
Fecal electron microscopy	Feces	Virus particles	Not widely available, turnaround time can be slow, and may be expensive. Requires the presence of large amounts of virus.
Virus isolation	Feces, tissues	CPV	Difficult, not widely available. Used as a research tool.

CPV, Canine parvovirus (refers to CPV-2 variants); IHC, immunohistochemistry.