Myocarditis in Puppies Associated with Parvovirus Infections in Western Romania

Perinatal parvoviral infection in puppies leads to necrotizing myocarditis, resulting in either high mortality or gradual heart damage. We believe that canine parvovirus 2 (CPV-2) myocardial infection is not being fully recognized as a cause of myocarditis, cardiac injury, and fibrosis repair in young dogs, despite the significant reduction in the epidemic of canine parvoviral myocarditis due to extensive vaccination. This study analyzed formalin-fixed, paraffin-embedded tissues obtained from 40 canine cases aged less than two years, spanning the period from 2019 to 2021. The objective was to test for the presence of CPV 2. Cardiac necrosis, inflammation, or fibrosis were observed in the diagnosed cases, but the age-matched controls did not have any cardiac abnormalities and tested positive for CPV. The presence of myocardial CPV-2 was detected in young dogs with mild myocarditis, suggesting that the period of vulnerability to myocarditis in the heart may be greater than what has been previously documented. CPV-2 was found in dogs who had extensive myocardial fibrosis, indicating that CPV-2 had caused previous injury to the heart muscle. Although vaccinations are common, these findings indicate that CPV-2 continues to be a major contributor to cardiac injury in dogs.