A description of cutaneous-subcutaneous pythiosis in fifteen dogs

Information regarding signalment, duration of clinical signs, history of sw imming, results of CBC and serum biochemical analyses, biopsy findings and mycological results, together with treatments and outcome, was retrieved fr om the medical records of 15 dogs with a diagnosis of pythiosis made betwee n 1985 and 1995 at the Colleges of Veterinary Medicine, North Carolina Stat e University and the University of Florida. Most of the dogs were young (me dian age 22 months) and represented larger breeds (> 20 kg). Lesions were c haracteristically chronic, ulcerated, and nodular with multiple draining tr acts on the limbs, thoracic wall or perineal regions. The median duration o f these lesions was 3 months with a range of 2 weeks-6 months. Seven dogs h ad a history of swimming. Peripheral eosinophilia was observed in 14 of the dogs. Cytological evaluation of discharge, aspirates, or impression smears made from biopsy specimens revealed hyphae in five of 11 dogs (45%). Histo pathological evaluation using the Gomori Methenamine-Silver (GMS) stain was the most useful test for providing presumptive evidence of cutaneous pythi osis. Immunotherapy or antifungal therapy using either amphotericin B, lipo somal nystatin, itraconazole, or ketoconazole were all unsuccessful. The on ly dog to survive underwent amputation of the affected limb; thus, the prog nosis for cutaneous pythiosis in the dog is poor.