Clinical and histopathological evaluation of terbinafine treatment in cats experimentally infected with Microsporum canis

The efficacy of terbinafine hydrochloride (Lamisil (R), Novartis) in the treatment of 27 M. canis-infected cats was followed. Treatment was started on the 17(th) day post inoculation (p.i.), when successful experimental infection was proved. Nine cats were treated with low-dose terbinafine 1020 mg/kg QD (LD group), nine cats were treated with high-dose terbinafine 30-40 mg/kg QD (HD group) and nine were left untreated as a control group (C group). The efficacy of the treatment was evaluated using Wood's lamp examination, fungal culture and histopathology. All cats were positive 14 days p.i. Sixty days p.i. 8 cats from the LD group, 9 from the C group and 2 cats from the HD group had fungi in the tissue. Ninety days p.i. the HD group was free of fungi in the skin and other tests became negative on the 120(th) day p.i. Statistically significant differences were found between the HD group and both of the other groups (p < 0.005) on 60(th) and the 90(th) day p.i. Experimental infection with M. canis yielded an inflammatory reaction of a mononuclear and neutrophil type in the cat skin. Hyperplastic interstitial dermatitis was a predominant tissue reaction although other types were also present during the study.