Breed and Sex Risk Factors for Canine Babesiosis in South Africa

Background: In South Africa, canine babesiosis typically is an acute disease in susceptible individuals and is a major cause of morbidity and mortality. Despite the importance of the disease, there have been no large studies that have examined the influence of breed and sex on disease susceptibility. Hypothesis: Toy breeds have a lower risk of babesiosis than working dogs. Animals: A total of 1,222 dogs diagnosed with canine babesiosis and 11,484 noninfected dogs presented to the Onderstepoort Veterinary Academic Hospital's small animal outpatient clinic between 2004 and 2010. Methods: Retrospective study. Results: Intact male, neutered male, and neutered female dogs had a significantly higher odds of being diagnosed with canine babesiosis compared to intact female dogs. Five of the 6 Toy breeds had significantly lower odds of being diagnosed with canine babesiosis than did the reference breed, Labrador Retrievers. In contrast, none of the 8 working dog breeds had significantly lower odds compared to the reference breed. Conclusions and Clinical Importance: Intact male, neutered male, and neutered female dogs were at increased risk of canine babesiosis compared to intact female dogs. Several dog breeds, notably Toy breeds, had a lower risk of babesiosis in a hospital population of dogs in South Africa. The mechanism or mechanisms by which Toy breeds are protected from developing canine babesiosis may be related to genetic background or environmental exposure and deserves further study.