Equine pythiosis is an endemic disease of horses and causes significant economic losses to equine breeding in the Brazilian Pantanal. This article describes 16 cases of subcutaneous pythiosis in horses from that region. The clinical cases were divided in typical (11) and atypical (5), according to the clinical features and duration of the disease. The clinical diagnosis was confirmed by detection of specific antibodies by ELISA, isolation of the agent and histopathology. The duration of the disease varied from 1 to 6 months in the typical cases and was over 12 months in the atypical ones. The lesions in the typical cases were characterized by subcutaneous ulcerated granulomas with abundant serosanguineous secretion and itching. The atypical cases presented subcutaneous lesions characterized by large, circumscribed tumorous masses covered by a dark non ulcerated skin, associated with little or no secretion. These lesions showed a well organized aspect, were sometimes pedunculate and the animals showed a good body condition. Histologically, the typical cases were characterized by granulation tissue with abundant eosinophils; whereas the atypical cases presented pseudo-epitheliomatous hyperplasia of the epidermis and eosinophilic infiltrate. The complete description of the clinical and histopathological features and possible factors responsible for differences between the two clinical forms are presented and discussed.
Pythiosis; Pythium insidiosum; equine; granuloma; Pantanal
