Generalized Microsporum canis dermatophytosis in six Yorkshire terrier dogs.

Six Yorkshire terrier dogs with generalized, chronic dermatophytosis caused by Microsporum canis were seen over a 3-year period. Specific tests showed that they also had concurrent leishmaniosis (four cases), leishmaniosis and ehrlichiosis (one case) or diabetes mellitus (one case). Although specific therapy for these infectious diseases was instituted and the dogs were treated systemically and topically with appropriate antifungal drugs, only partial clinical resolution of the dermatophytosis was achieved. M. canis infection resolved in the dog with diabetes mellitus after stabilizing the diabetes mellitus. Although immunological studies were not performed in these cases, it is theorized that the immune disregulation caused by leishmaniosis, ehrlichiosis or diabetes mellitus may have favoured generalization of the infection and prevented favourable responses to appropriate treatment of the M. canis infection.