Fistulous Withers or Poll Evil

Fistulous Withers: Function: noun plural but usually singular in construction. A deep-seated chronic inflammation of the withers of the horse that discharges seropurulent or bloody fluid through one or more openings and is probably associated with infection by bacteria of the genus Brucella (especially B. abortus). Merriam-Webster Medical Dictionary

A number of occurances can cause a fistulous withers. Your horse can have a traumatic injury that manifests itself into a fistulous withers. Poorly fitting saddles that put too much preseure on the withers can cause a fistulous withers. Also a fistulous withers can be caused by infection. Titers can be done to determine what is causing the infection. Fistulous withers is an inflammatory condition. You may not see a fistula until a bursal sac wall thickens, ruptures, drains, and gets a secondary infection with pyogenic bacteria. Then the fistula forms. You may see a clear or yellow colored ooze. There will probably be swelling in the area. Early treatment is really important because fistulous withers can be very difficult to clear up. It is very much like a really bad sinus infection. The culprit Brucellaabortus most commonly manifests as fistulous withers in horses. It should be noted that this can be transmitted to humans and cattle, as well. Be extremely careful around it. This is considered a public health issue and is usually reported. Treatment can vary, however, complete dissection and removal of the infected bursa has the most successful results.

Poll evil is very much like a fistulous withers. Its location is different. The dynamics, symptoms and treatment are relatively the same.