The growth fraction of 68 canine cutaneous melanomas was determined by immunostaining with MIB-1, a monoclonal antibody to a Ki-67 epitope that recognizes all proliferating cells. Fifty tumours were classified histologically as benign and 18 as malignant. The Ki-67 proliferative index (percentage of positive cells over 500 neoplastic cells) was low (< 15%) in 55 cases and high (> or = 15%) in 13 cases. High Ki-67 proliferative index and histological malignancy were both associated with significantly poorer 2-year survival (P < 0.0001). However, the predictive value of the Ki-67 proliferative index (97%) was higher than the predictive value of classical histology (91%). The evaluation of the growth fraction by the Ki-67 proliferative index is highly predictive of the biological behaviour of canine cutaneous melanoma.

This report describes the immunohistochemical detection of the Ki-67 proliferation associated nuclear epitope by means of the MIB-1 monoclonal antibody (mAb) in paraffin tissue sections from nine samples of 16 tissues obtained from nine dogs. Three parameters were considered: the localization of the cells expressing the Ki-67 epitope, the cytological characteristics of the Ki-67 expression, and the proliferative activity of some of the tissues measured by means of the proliferative index (percentage of Ki-67 positive cells measured on 500 and 1000 cells). The MIB-1 mAb reacts with the nuclei of proliferating cells, as in humans. The proliferative index was far from representative, but we were able to give a range of values concerning the proliferative activity of normal tissues. This study serves as a basis for the expression of the Ki-67 antigen by normal canine tissues in order to visualize the proliferative compartments and, thus, allows its application as a proliferative marker in routine veterinarian histopathology.

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During the last few years, reports have appeared claiming that lufenuron diminished or even cured dermatophyte infections in cats and dogs. As these observations have a rather anecdotal character leading to some ambiguity in the literature, it was decided to test lufenuron in a generally accepted animal model for dermatomycotic infection. The test was carried out in guinea pigs artificially infected with Microsporum canis on scarified dorsal skin and orally treated with lufenuron (Programä). The efficacy of up to five doses of 80 mg/kg was assessed 7 and 14 days after the start of treatment. All animals failed to show any improvement in skin lesions as compared to the vehicle-only treated animals. Clinical symptoms taken into account were scaling, crust formation, erythema, and exudation. Neither the number of treatments (one or five) nor the dose range (40 or 80 mg/ kg) made any difference. Itraconazole, tested earlier under identical circumstances, resulted in a clear and consistent improvement at day 7 of the infection at a dose of 15 mg/kg, given either in one dose or spread over several days. The absence of antimycotic activity of lufenuron in this established animal model constitutes a significant element in the discussion on the antifungal potency of lufenuron and supports the fact that there is, as yet, no evidence that benzoylphenyl urea derivative compounds have an effect on chitin synthesis in fungi.