Pythiosis is an uncommon and often fatal fungal infection that occurs in dogs, and rarely in cats. In dogs, it is generally contracted when animals with open sores drink, stand, or swim in stagnant water. It is caused by the aquatic mold Pythium insidiosum. Pythium is found in stagnant water throughout the southern United States, particularly around the Gulf Coast region.
What are the symptoms of pythiosis?
Worldwide, the gastrointestinal form of the disease is most common. The subcutaneous (skin) and nasopharyngeal (nose and throat) form of the disease is less common, but is more likely to occur in cats and dogs living in the southeastern United States. Pythium enters the tissue of the animal through open sores or wounds. The infections appear as large swollen nodules that will ulcerate and drain. The lesions are the most common on the legs, head, and at the base of the tail. The lesions may itch and are often confused with other granulomatous conditions.
How is pythiosis diagnosed?
Infections with the Pythium fungus can be difficult to diagnose. Occasionally, the organism can be identified by taking swabs or biopsies and then identifying the fungus under the microscope. Material from swabs and biopsies can also be cultured in the laboratory. However, pythiosis is often diagnosed after all other diseases have been ruled out. Researchers are attempting to develop a blood test to aid in the diagnosis of this disease.
What is the treatment for pythiosis?
Unless the disease is diagnosed early in its course, it is generally fatal. Treatment usually consists of surgical excision of the nodule(s). Unless the entire nodule can be removed, the prognosis is very poor. Oral or topical treatment with antifungal agents have not been shown to be very successful.