Canine and feline dermatophytosis due to Microsporum gypseum: A retrospective study of clinical data and therapy outcome with griseofulvin

Objective. - Microsporum gypseum is a common inhabitant of the soil, occasionally responsible for human and animal ringworm. Few reports describe the treatment of dermatologic diseases due to M. gypseum. The objective of this study was to evaluate retrospectively cases of M. gypseum infection in dogs and cats. Material and methods. - The occurrence of infection by this dermatophyte was retrospectively evaluated in dermatological specimens from 15,684 dogs and cats dermatologically diseased from Italy. Clinical outcome after treatment with griseofulvin combined with topical enilconazole was evaluated in 41 dogs and, out of label, 10 cats. Furthermore, in vitro susceptibility to griseofulvin and enilconazole was evaluated on 31 clinical isolates of M. gypseum. Results. - One hundred and eighty-five specimens out of 15,684 (1.1%) scored positive for M. gypseum. The treatment failed to achieve both mycological and clinical cure in 16 dogs (39%) and four cats (40%), as well as fungal isolates demonstrated a very poor in vitro sensitivity when tested versus griseofulvin: the MIC value was 150 mu g/mL. The ED50 value was calculated at 66 mu g/mL. Conclusion. - Blind treatments with griseofulvin in ringworm due to M. gypseum should be avoided.