(aka: bursatte, leeches, swamp cancer, kunker disease)

Pythium insidiosum is the proper name for the organism that can be found in plants, birds and mammals during the environmental conditions that contain or favor warm temperatures, flooded lands, and and aquatic vegetation. In horses, pythiosis causes ulcerative, granulomatous lesions on the skin and just below the skin level.

-In horses, often the lesions are found in the skin of the limbs, chest and abdomen, but can be found in other areas of the body such as the eye and the gastrointestinal tract. More often, the lesions are found on the body parts that are in direct contact with WATER that contains the zoospores (the infective stage of Pythium insidiousum). In order for the zoospores to enter the body, a puncture or bite wound (mosquito) must occur as a break in the skin. There is a proposed association between the lesion locations and the areas of insect blood feeding.

-Incubation time is suspected to be 15-20 days. Granulomatous, ulcerative lesions occur at the infection site. Often there may be a draining tract associated with it and blood or serous fluid may be draining from the lesion. The lesions may be firm and may contain necrotic (dead) gray material often known as “Kunkers”. If the material of the kunker is examined under the microscope, fungal hyphae can be identified. This is important to differentiate pythiosis from sarcoids, squamous cell carcinoma and granulation tissue.

-Pythiosis is NOT contagious.

-Predisposing factors are not clearly understood, but horses standing in ponds or flooded areas have an higher incidence of coming into contact with Pythium insidious. The number of cases will significantly increase during rainy periods in the summer season.

-Treatment of pythiosis may involve a combination of surgical removal of the affected tissue, chemotherapy, and immunotherapy.

-Prevention is difficult, but avoiding wetland environments during warm seasons may offset contact with this organism.

As always, we recommend veterinary examination for any lesion that becomes difficult to treat, is fast-growing, and has a sero-sanguineous (bloody to golden) discharge.

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