Descriptive epidemiology of companion animal dermatophytosis in a Canadian Pacific Northwest animal shelter system

This study investigated the frequency of false positive dermatophyte cultures, dermatophyte prevalence, and dermatophytosis risk factors in an animal sheltering system in British Columbia. Records for 80 471 incoming shelter animals over 3.5 years were accessed retrospectively. For 831 high-risk animals cultured, the false positive rate was 28% [N = 229; 95% confidence interval (CI): 25% to 31%]. Microsporum canis was diagnosed in 201 cases (0.25%, 95% CI: 0.22% to 0.29%) and Trichophyton was diagnosed in 43 cases (0.055%, 95% CI: 0.040% to 0.072%). Microsporum canis cases occurred only in cats and rabbits, but not in dogs. Cats were twice as likely to be diagnosed with Trichophyton as dogs. Puppies and kittens ( versus adults) and animals from cruelty investigations (versus other sources) were significantly more likely to be diagnosed with dermatophytosis. Animals seized from 4 cruelty cases with enzootic dermatophytosis did not follow overall prevalence or population risk patterns. Understanding patient and population risk factors can help expedite diagnosis, treatment, and recovery, and reduce contagious risk to humans and animals.