Equine warts are small, grey to pink cauliflower-like growths that generally appear on a young horse s muzzle or lips. They can also be found on the face, ears or less commonly on the lower legs. They occur singularly, scattered, or in clusters. Most infections result in 10 to 20 warts, yet numbers over 100 can also occur.
Warts are an ailment of younger horses, typically six months to three years of age. They are caused by a papilloma virus which is considered to be very contagious to susceptible horses. Their presence can be linked to a developing immune system, because warts develop less frequently and disappear more quickly in youngsters whom are healthy with suitable nutrition.
Transmission may occur directly from horse to horse, but transmission can also be spread by objects or materials that are likely to carry infection such as fence posts, feed buckets and tack. The virus can remain active in the environment for variable periods. In addition flies and humans may act as vehicles for spread. Consequently good hygiene and limited contact with affected horses are advisable. Although both humans and horses can get warts, equine warts are not contagious to humans since the virus is species specific.
Despite their unsightly appearance, warts seldom affect the overall health of a horse. They are a self-limiting condition for as immunity develops the warts fall away without treatment. They generally persist for a variable time, six to 12 months, and disappear without intervention.
In spite of their fragile appearance warts are quite hardy to scraping or injury. It is tempting to surgically remove warts or place a caustic agent on them, especially when they are numerous, but these methods often scar the delicate tissue of the face. When allowed to remedy on their own not a blemish is left. Patience brings the best result for warts. Management of warts in young horses focuses on supporting the youngster and his/her developing immune system. This includes nutrition, particularly mineral support, a favourable environment, a balanced social structure and an adequate deworming program. Often horses that develop warts are undergoing a stressor such as parasite infestation, malnourishment, a growth spurt, or strained social dynamics.
This same papilloma virus is also suspected to be responsible for the small, circular, flat, white plaques that occur on the inside surface of horse s ears. These plaques may be few or many and active plaques may have a waxy or flaky discharge. Although most often aural plaques are an incidental finding on the inside of the ears, there are some horses that develop extreme sensitivity around their ears, especially during the summer months when discharge from the plaques attract flies.
Be aware of this sensitivity when haltering or bridling. Fly protection and cleaning of the ears may be necessary to keep the horse comfortable. There is no specific treatment for aural plaques for, like warts, they resolve spontaneously, leaving their characteristic depigmented footprint.
Carol Shwetz is a veterinarian specializing in equine practice at Westlock, Alberta.