A malignant melanoma, a giant pigmented tumor of a 10-year-old, male mixed-breed dog at the oral mucosa, and a benign melanoma, a black macule of a 14-year-old, female Shetland sheepdog at the pinna, were investigated. Histopathologic examinations revealed severe proliferation of the pigmented cells in both cases. Fluorescence method of formalin-fixed paraffin-embedded unstained specimens (fluorescence method) was performed, and some pigmented cells showed specific fluorescence in the malignant melanoma, but not in the benign melanoma. The pigmented cells of the pigmented oral mucous in the malignant case were also examined by the fluorescence method, but failed to show any specific fluorescence. It was demonstrated that pigmented cells in canine malignant melanoma showed specific fluorescence as well as those in the case of humans, which indicated that the specific fluorescence of melanocytes was associated with malignant proliferative properties.

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Long-term administration of glucocorticoid had aggravated the skin lesions in a Golden Retriever with chronic refractory pruritic dermatopathy. The skin biopsy revealed cutateous calcinosis with intence inflammatory reaction suggesting iatrogenic Cushing's syndrome. Discontinuance of the glococorticoid administration resulted in remarkable improvement of the skin lesions as well as pruritis.

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A canine case of spontaneous Cushing's syndrome was found to be infected with Demodex canis, Staphylococcus intermedius and Malassezia pachydermatis. The treatment was performed mainly for Cushing's syndrome resulting in the disappearance of the skin involvement caused by these infection.

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