Definition
A fibropapilloma, or papilloma, is the common wart, composed of skin and connective tissue cells and caused by species-specific papillomaviruses.
How Warts Affect Dogs
Warts are extremely contagious between dogs. They can appear anywhere on a dog’s body and usually look like tiny cauliflowers, but occasionally are smooth. Older dogs tend to develop isolated warts, commonly on the feet, around the toes and footpads and on the under-belly. These warts can start and stay small, or they can increase in size. Young dogs usually develop warts in clusters, often inside the mouth, around the eyes or elsewhere on the face or on their genitalia. Puppies are especially prone to developing warts because they have naïve immune systems and commonly lick and romp rambunctiously with other dogs. Warts are painless and generally do not require treatment for medical reasons. They can be removed for cosmetic reasons or if they cause the dog discomfort (lameness when they are between the toes or affecting the footpads or interference with vision or eating). While warts are usually harmless, they can bleed and become ulcerated, infected and painful if scratched or chewed. Uncommonly, they transform to malignant squamous cell carcinoma. Canine warts often regress spontaneously within one year.
Causes of Warts in Dogs
“Warts” are growths caused by papilloma viruses – a group of DNA viruses that induce proliferative, species-specific and usually benign skin and mucosal tumors in dogs. The underlying cause is thought to be immune-mediated, and there appears to be a genetic component in certain breeds. Dogs on chronic corticosteroid therapy frequently become immunocompromised and are more likely to develop papillomas. Infection by a papilloma virus requires inoculation through a break in the skin or mucosa, normally through direct contact with an infected dog or possibly through veterinary use of a contaminated instrument.
Preventing Warts
There is no foolproof way to prevent development of warts in dogs. Dogs known to have oral papillomas should be kept away from susceptible dogs. Chronic use of steroid therapy should only be used when medically necessary. A papillomavirus vaccine is now available and shows promise.
Special Notes
A number of skin conditions can be confused with warts, some of which are very serious. All lumps and bumps on dogs should be checked by a veterinarian. If surgical removal of a wart is desired, it is normally accomplished by traditional excision, cryosurgery, laser ablation or electrosurgery/electrocautery. The prognosis for dogs with warts is very good, since most cases resolve on their own. Warts are not transmittable between dogs and people, because they are species-specific.