Canine parvovirus cases (2010-2023): a retrospective study of 78,977 cases demonstrates declining incidence, but mortality risk remains.

OBJECTIVE: To investigate changes in characteristics of dogs diagnosed with canine parvovirus (CPV) disease presenting to a national network of primary care veterinary hospitals. METHODS: Records were searched from January 1, 2010, through June 30, 2023. Data were collected on signalment, clinical signs, laboratory results, and mortality for CPV-affected dogs. Variables were assessed via stepwise logistic regression models for association with mortality. RESULTS: Across > 1,000 hospitals, CPV was diagnosed in 78,977 dogs, declining from 45.2 cases per 10,000 dogs per year in 2010 to 6.5 cases per 10,000 dogs per year in 2022. Diagnoses were greatest in April to June, while 46.3% of cases were aged between 8 and 16 weeks. From 2010 to 2022, median age at diagnosis declined from 17 to 14 weeks. The most commonly affected breeds were pit bull-type dog, Chihuahua, Labrador Retriever, German Shepherd Dog, and mixed breed (combined, 54.3% of the study population). Of 37,707 patients with 14-day survival information, 43.6% died or were euthanized. Being neutered or spayed (OR, 0.04; 95% CI, 0.02 to 0.08), having increased body weight, or having multiple intestinal parasites significantly reduced odds of mortality. Variables significantly associated with increased odds of mortality were hypoproteinemia (OR, 4.44; 95% CI, 2.01 to 9.81), underweight (OR, 2.99; 95% CI, 1.40 to -6.36), lymphopenia, leukopenia, and increased ALT. CONCLUSIONS: The number of CPV cases and mortality declined over the study period. However, CPV infections still occur in thousands of dogs annually, and risks of mortality persist. CLINICAL RELEVANCE: Dogs remain at risk of fatal CPV infection. Identification of mortality-associated factors may allow more targeted interventions and improve prognostic capabilities.