bone. In humans it can cause arteritis, keratitis, and periorbital cellulitis. In cats pythioisis is almost always confined to the skin as hairless and edematous lesions. It is usually found on the limbs, perineum, and at the base of the tail. Lesions may also develop in the nasopharynx. Pythium insidiosum is different from other members of the genus in that human and horse hair, skin, and decaying animal tissue are chemoattractants for its zoospores, in addition to decaying plant tissue. Zygomycosis Zygomycosis usually is a disease of the skin, but can also occur in the sinuses or gastrointestinal tract. In humans it is most prevalent in immunocompromised patients (HIV/AIDS, the elderly, SCID, etc) and patients in acidosis (diabetes, burns), particularly after barrier injury to the skin or mucus membranes. Zygomycosis caused by Mucorales causes a rapidly progressing disease of sudden onset in sick or immunocompromised animals. Entomophthorales cause chronic, local infections in otherwise healthy animals. The important species that cause entomophthoromycosis are Conidiobolus coronatus, C. incongruous, and Basidiobolus ranarum. Conidiobolus infections of the upper respiratory system have been reported in humans, sheep, horses, and dogs, and Basidiobolus has been reported less commonly in humans and dogs. Horses are one of the most common domestic animals to be affected by entomophthoromycosis. C. coronatus causes lesions in the nasal and oral mucosa of horses that may cause nasal discharge or difficulty breathing. B. ranarum causes large circular nodules on the upper body and neck of horses. Entomophthorales is found in soil and decaying plant matter, and specifically Basidiobolus can be contracted from insects and the feces of reptiles or amphibians. Zygomycosis of the sinuses can extend from the sinuses into the orbit and the cranial vault, leading to rhinocerebral mucormycosis. Lagenidiosis The best known species of Lagenidium is Lagenidium giganteum, a parasite of mosquito larvae used in biological control of mosquitoes. Two different species cause disease exclusively in dogs: L. caninum and L. karlingii. Lagenidium is found in the southeastern United States in lakes and ponds. Lagenidiosis causes progressive skin and subcutaneous lesions in the legs, groin, trunk, and near the tail. The lesions are firm nodules or ulcerated regions with draining tracts. Regional lymph nodes are usually swollen. Spread of the disease to distant lymph nodes, large blood vessels, and the lungs may occur. An aneurysm of a great vessel can rupture and cause sudden death. L. caninum is the more