Canine parvoviral myocarditis

Abstract

A 5-week-old crossbred pigdog pup was presented in respiratory distress. It appeared to dry retch, and then died suddenly before a clinical examination was performed; a littermate had died suddenly the week before. Histopathological examination revealed an ongoing lymphocytic myocarditis, characterised by myofibril degeneration and lymphocytic inflammatory infiltrates. In scattered degenerate myofibres, there were large amphophilic intranuclear inclusion bodies distending their nuclei. There was also marked pulmonary oedema. Canine parvoviral myocarditis, due to canine parvovirus type 2, was diagnosed. Further questioning regarding the history of this pup revealed that it had been born to an unvac-cinated dam that had been moved late in her pregnancy from an isolated farm on to another property. It seems likely that the dam was naïve and only became exposed to the virus immediately prior to whelping. The lack of wildlife vectors and a well-controlled population of dogs in rural New Zealand means that there may be isolated areas of the country where dogs can reach maturity without becoming exposed to parvovirus, creating the potential for development of this now uncommon syndrome. When parvovirus first arose in New Zealand, between 1979–;1981, parvoviral myocarditis was relatively common, occurring in neonates when the virus was introduced to breeding kennels that previously had been unexposed.