Equine warts are small lumps (papillomas) which appear on the skin of the horse; caused by infection from the equine papilloma virus, a virus member of the papillomaviridae family. Typically, equine warts are not a serious threat to a horse’s health, but merely a cosmetic defect; however, there is a high risk of infection spreading to other horses located in the same vicinity.
Equine Papilloma Virus Infection
Presently, it is not fully understood how the equine papilloma virus infection initially enters the system, although, it is widely accepted that it can gain access through minimal skin wounds. Minor abrasions, such as those commonly sustained by young horses rubbing their muzzles on various objects, can become exposed to the papilloma virus, leading to an infection. This theory also lends an explanation to the extremely high occurrence of papillomas forming around the muzzle area.
The equine papilloma virus is a highly contagious viral disease, with transmission of the virus occurring via direct contact between horses, or as result of contact with infected equipment. Equines up to the age of 3 to 4 years, due to immature immune systems, are extremely susceptible to equine warts; older equines are less susceptible, but are not completely free from risk.
Equine Papilloma Symptoms
Equine papillomas first appear as hard, tiny grey swellings, most commonly occurring on the muzzle, around the eyes and under the tail; but can occasionally be found on other parts of the body. Slowly growing to anything between 5 and 20mm in size, the lesions turns to a pinky grey colour; the warts can grow in a cluster of many lesions (papillomatosis) creating a cauliflower-like appearance, or as a singular papilloma.
The incubation period for equine warts is 2 to 3 months, growing to maturity and typically disappearing over a further 3 to 6 months; however, some cases can prove more troublesome, taking up to a year to regress.
Equine Warts Diagnosis
It is recommended that a qualified veterinary practitioner be consulted in the diagnosis of equine warts. In most cases, diagnosis is based on appearance, history of papillomas and veterinary observation; however, some types of equine sarcoids can bare a resemblance to equine warts and misdiagnosis can occur, especially if the lesion is large in size. Should a diagnosis be questionable, a biopsy sample may be collected for histologic analysis.
Infection Control for Equine Papillomas
Infection control of equine papillomas virus is vital, especially where horses are stabled or grazed in close proximity.
- Isolation – Where possible, any horse suspected of having equine warts should be isolated from the rest of the group immediately
- Premises Disinfection – Disinfection of areas where an infected horse has frequented is strongly recommended; areas such as stable, walker, horse lorry and horse trailer are but a few suggestions. Where American barn style stabling are in use, it is a good idea to disinfect the whole of the inside, including each individual stable, feed room, tack room, kitchen and toilets. Chlorhexidine, Virkon and iodine are some disinfectants which can be used
- Equipment Disinfection – Disinfecting general equipment, such as feed bowls, grooming brushes, water buckets, bridles and head collars are a necessity in minimising the spread of equine warts. Saddle pads and travel rugs can be washed in a hot wash with disinfectant added; where possible, everyday rugs should also be disinfected
- Separate Equipment – It is essential to use separate equipment on infected and non-infected horses. Ideally, a set of equipment, such as brushes, bridles and head collars should be set aside just for the use on affected horses
Treatments of Equine Warts
Typically, equine warts will regress spontaneously, without the need for treatment. However, there are various treatments available, should they be required.
- Surgical Removal – Usually recommended when the papillomas are of sufficient concern, such as interfering with eating or severe irritation. However, removal should be done when the warts are near full size to prevent the risk of recurrence; this treatment is often successful, but can leave scarring or blemishes
- Cryosurgery – This treatment is generally successful and requires the warts to be frozen with liquid nitrogen, often recommended where a concern is raised; however, the treatment can leaving scarring or blemishes
- Topical Creams – There are many treatments of this sort available, success is varied
Equine Warts – an Overview
Veterinary advice should be sought where a case of suspected equine papillomas arise, and good hygiene practices should be implemented to reduce the risk of the disease spreading. Secondary infections can arise when warts are knocked or scraped, creating an open wound; these may require further veterinary attention.
- The Merck Veterinary Manual – accessed 9 February 2011
- Tony and Marcy Pavord, The Complete Equine Veterinary Manual, David & Charles, 1999.
- Frosty Franklin, DVM, Veterinary Corner 10/01: Warts & Aural Plaques – accessed 9 February 2011
- William Miller, Jr., VMD, Dipl. ACVD, The Horse.com: Warts – accessed 9 February 2011