Phycomycosis is an uncommon condition affecting the gastrointestinal tract and skin, most commonly found in dogs and horses. The condition is caused by various molds and fungi, with individual forms including pythiosis, zygomycosis, and lagenidiosis. Pythiosis, the most common type, is caused by Pythium, a type of water mould. Zygomycosis can be caused by two types of zygomycetes: Entomophthorales (e.g., Basidiobolus and Conidiobolus) and Mucorales (e.g., Mucor, Mortierella, Absidia, Rhizopus, Rhizomucor, and Saksenaea). The latter type of zygomycosis is also referred to as mucormycosis. Lagenidiosis is caused by a Lagenidium species, which like Pythium is a water mould. Since both pythiosis and lagenidiosis are caused by organisms from the Oomycetes and not the kingdom fungi, they are sometimes collectively referred to as oomycosis.