Medical Mycology 1999, 37, 427 – 433 Accepted 24 April 1999 A description of cutaneous – subcutaneous pythiosis in fifteen dogs M. J. DYKSTRA,* N. J. H. SHARP,† T. OLIVRY,† A. HILLIER,‡ K. M. MURPHY,† L. KAUFMAN,§ G. A. KUNKLE¶ & C. PUCHEU-HASTON† *Microbiology, Pathology and Parasitology Department,†Companion Animal and Special Species Department, College of Veterinary Medicine, North Carolina State University, Raleigh, NC,‡Department of Veterinary Clinical Sciences, The Ohio State University, Columbus, OH,§Immunodiagnostic Laboratory, Division of Bacterial and Mycotic Diseases Branch, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA, and ¶Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA Information regarding signalment, duration of clinical signs, history of swimming, results of CBC and serum biochemical analyses, biopsy findings and mycological results, together with treatments and outcome, was retrieved from the medical records of 15 dogs with a diagnosis of pythiosis made between 1985 and 1995 at the Colleges of Veterinary Medicine, North Carolina State University and the University of Florida. Most of the dogs were young (median age 22 months) and represented larger breeds ( 20 kg). Lesions were characteristically chronic, ulcerated, and nodular with multiple draining tracts on the limbs, thoracic wall or perineal regions. The median duration of these lesions was 3 months with a range of 2 weeks – 6 months. Seven dogs had 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%). Histopathological evaluation using the Gomori Methenamine-Silver (GMS) stain was the most useful test for providing presumptive evidence of cutaneous pythiosis. Immunotherapy or antifungal therapy using either amphotericin B, liposo- mal nystatin, itraconazole, or ketoconazole were all unsuccessful. The only dog to survive underwent amputation of the affected limb; thus, the prognosis for cutaneous pythiosis in the dog is poor. Keywords canine, diagnosis, pythiosis, therapy Introduction Pythium insidiosum De Cock, Mendoza, Ajello et Kauf- man infections of dogs have only been reported since the 1980s [1] even though equine ulcerative granulomatous lesions associated with a condition called swamp cancer, and attributed to a sterile fungus originally named Hy - phomyces destruens Bridges et Emmons, were described as early as 1884 [2]. The causative agent for equine infections was later identified as being a member of the oomycete genus Pythium [3], and the species P. insidiosum was created in 1987 [4,5] for isolates that cause mam- malian disease. P. insidiosum infections have been re- ported as the cause of gastrointestinal disease in over 60 dogs [6 – 9], granulomatous dermatitis in dogs [10], infec- tions in cats [9,11], mycotic keratitis in humans [12], Correspondence: Dr Michael J. Dykstra, Microbiology, Pathology and Parasitology Department, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606, USA. Fax: +1 919 513 6455. © 1999 ISHAM Downloaded from https://academic.oup.com/mmy/article-abstract/37/6/427/1009354 by guest on 11 June 2020