Papillomatosis is a skin condition in horses, caused by several equine papillomaviruses. Papillomavirus type 1 (EcPV-1) is associated with the development of cutaneous papillomas (warts) on the lips and muzzle of horses. They can also appear on the horse's ears, eyelids, genitalia or lower limbs. Equus caballus papillomavirus type 2 has been isolated from papillomas and squamous cell carcinomas (SCC) affecting the genital area of horses.

A third equine papillomavirus was recently isolated from an ear papilloma which is thought to be the possible cause of aural plaques found in horses' ears. In the majority of horses, the warts spontaneously disappear 1 to 6 months after they initially appear; however genital lesions are suspected to progress to SCC and should be considered potential premalignant lesions.

Transmission
Warts are spread by fomites or by close contact with affected horses.

Incubation Period
The incubation period is estimated to be approximately 60 days, but may be influenced by the route of exposure, dose of virus, and immunity of the host.