Pythiosis is characterized most commonly by ulcerative dermatitis, mainly in the limbs of sheep and occasionally of goats. In sheep, Pythium insidiosum is also responsible for necrotizing rhinitis characterized by marked enlargement and deformity of the nasal region, severe respiratory difficulty, and bloody nasal discharge. A third form of pythiosis in sheep affects the digestive tract, involving ulceration of the esophagus, forestomachs, and abomasum. Pythiosis in sheep and goats has been reported only in Brazil where it occurs mainly in the semiarid region of the country, when animals congregate and stay for longer periods of time within or around water reservoirs. However, it has been reported as well in areas of humid environments, such as the Pantanal of Mato Grosso and in the Brazilian Cerrado. The diagnosis of the different presentations of pythiosis is based on gross and microscopic findings, coupled with detection of the agent by immunohistochemical, molecular, and/or culture-based methods.

Pythiosis 最常见的特征是溃疡性皮炎，主要发生在绵羊的四肢，偶尔发生在山羊的四肢。在绵羊中，Pythium insidiosum坏死性鼻炎也是坏死性鼻炎的罪魁祸首，其特征是鼻区显着增大和畸形、严重的呼吸困难和流血性鼻涕。绵羊中的第三种形式的pythiosis影响消化道，包括食道、前胃和皱胃的溃疡。仅在巴西报告了绵羊和山羊的 Pythiosis，它主要发生在该国的半干旱地区，当动物聚集并在水库内或水库周围停留较长时间时。然而，在潮湿环境地区也有报道，例如马托格罗索州的潘塔纳尔湿地和巴西的塞拉多。pythiosis 不同表现的诊断是基于大体和显微镜检查结果，再加上通过免疫组织化学、分子、