Cutaneous pythiosis in equines in the Amazon Biome

J.D., Oliveira H.G.S., Bosco S.M.G., Silveira N.S.S., Barbosa C.C., Brito M.F., Oliveira C.M.C. & Salvarani F.M. 2023. Cutaneous pythiosis in equines in the Amazon Biome. Pesquisa Veterinaria Brasileira 43:e07167, 2023. Instituto de Medicina Veterinaria, Universidade Federal do Para, BR-316 Km 61, Saudade II, Cristo Redentor, Castanhal, PA 68740-970, Brazil. E-mail: felipems@ufpa.br The study aimed to describe the clinicopathological aspects of 37 cases of pythiosis, 34 in horses and three in mules, from properties located in the Amazon biome of Para, Brazil. The clinical signs observed in the animals were weakness, poor-to-regular nutritional status, pale mucous membranes, itching at the lesion site, and lameness when the limbs were affected. The lesions were located on the lips, nostrils, rib region, thoracic and abdominal walls, scapular, distal limbs, foreskin, perineum and udder. Macroscopically, ulcerative and granulation-tissue-like masses were observed, with fistulous tracts filled with yellowish and foul-smelling serosanguinous discharges. In the biopsy, it was possible to visualize white and firm areas with foci of yellowish necrotic material and hardened masses, called kunkers. The histopathological examination showed a pyogranulomatous inflammatory reaction with the presence of Pythium insidiosum hyphae, which were impregnated with black, confirming the diagnosis of pythiosis in equids in the Amazon biome, being the first report of the disease in mules in the region.