Mastite por Pythium insidiosum em éguas / Mastitis by Pythium insidiosum in mares

ABSTRACT

Background: Pythiosis is a chronic inflammatory disease caused by the oomycete Pythium insidiosum. This disease hasbeen reported in several species, but most cases occur in horses. In this species, the cutaneous form is more prevalent,with occasional involvement of adjacent lymph nodes and bone tissue. The involvement of the mammary glands was notproperly characterized. Therefore, the aim of this study is to describe cases of pythiosis with the involvement of the mammary glands in mares.Case A retrospective study of all biopsy samples and necropsy examinations of horses, performed at the Animal PathologyLaboratory of the Federal University of Campina Grande from January 2000 to December 2018, was carried out. During thestudy period, 142 cases of cutaneous pythiosis were identified. Of these, in three the lesions extended to the mammary glands.Mares with 3-, 7- and 12-year-old, mongrel, from the backlands of the Paraiba were affected. On physical examination, themares presented swollen mammary glands and multifocal wounds, which discharge serosanguinolent secretion. Clinicalevolution ranged from 15 to 30 days. The animals had been medicated, but the wounds did not heal and mastectomies wereperformed. Macroscopically, the mammary glands were enlarged and with multifocal areas of ulceration measuring 1 to 3.5cm in diameter. At the cut surface, they exhibited fistulous tracts containing kunkers. In the histopathological evaluation,was observed diffuse and marked inflammatory infiltrate of eosinophils extending through the deep dermis and interlobularmammary stroma; and multifocal areas, sometimes focally extensive, of eosinophilic necrosis with intralesional negativeimages of hyphae. In histological sections stained by periodic acid-Schiff, the walls of the hyphae were weakly stained inblue; but when impregnated by Grocott methenamine silver, they were strongly marked in black...(AU)