Incidence and risk factors for canine mastitis and metritis in two guide dog populations

Canine mastitis and metritis can cause severe illness but the incidence and risk factors have not been well-studied. Goals in the present study were: 1) report the incidence of mastitis and metritis in a large population, and 2) identify potential risk factors that predispose females to those diseases. A retrospective cohort study was conducted using data from two guide dog colonies that was collected for 17 and 10 years, respectively, for the two colonies. A total of 3076 whelpings occurred during the respective study periods and data were analyzed. Clinical mastitis was diagnosed in 13.2 % of whelpings (408 cases) with the average day of diagnosis being 16.7 postpartum. Risk factors for mastitis identified were colony, litter size where bitches that had large litter size of ≥9 pups (16.2 %) were 60 % more likely to develop mastitis compared with bitches that had litters of <9 pups (11.3 %). Bitches with congestion of the mammary gland were 4.8 times more likely to develop mastitis compared with bitches without mammary congestion. Case incidence of metritis was small (0.7 % of whelpings) and occurred on average at day-5 postpartum (range 1-16). There were no significant risk factors identified, and this may be due to the small number of metritis cases (22 cases) in the present study. Interpretations regarding metritis, therefore, should be made with caution. The results from this study provide parameters for breeders and veterinarians to identify bitches that may require close monitoring for mastitis and metritis.