By Jennifer Coates, DVM
Canine viral papillomatosis sounds serious, doesn’t it? Actually, the term is just a technical description for warts (papillomas) in dogs. While a diagnosis of dog warts is rarely dire, the condition is worth your attention, primarily so you don’t confuse warts in dogs with other, nastier diseases.
Symptoms of Dog Warts
Any dog can get warts, but they are more common in young animals, dogs who are immunosuppressed, canines who spend a lot of time around other dogs, and in certain breeds like Cocker Spaniels and Pugs. Warts on dogs are described as looking like a small head of cauliflower, but other, rarer types do exist, including an inverted papilloma (usually a firm lump with a dot in the middle) and dark, scaly plaques of skin that have an irregular surface. Warts can develop in and around a dog’s mouth, around the eyes, between the toes, and almost anywhere on the skin. In most cases, a veterinarian can diagnose a dog with warts with just a physical examination.
Some dogs develop one or just a few warts that are so small they are easy to overlook. In other cases, entire regions of a dog’s body may be covered with warts of varying sizes. Warts in and around a dog’s mouth may make it difficult for a dog to eat and drink normally. Warts on a dog’s feet can cause lameness, particularly if they become traumatized or infected.
What Causes Dog Warts?
Warts in dogs are caused by infection with a papillomavirus. Dogs with warts are contagious to other dogs, but not to other animals or people. Many different types of canine papillomaviruses have been identified and each type tends to cause a particular form of the disease (e.g., warts in and around the mouth versus warts affecting the feet). Once a dog has been infected with one type of papillomavirus he is immune to that type but not to others.
Dogs catch papillomavirus through a weakness or break in the skin from other dogs who have the virus. Papillomavirus can live in the environment for weeks, so it’s possible for a dog with warts to leave the virus behind in a particular area and then for another dog to pick up the virus from that area at a later time. It generally takes a month or two for warts to develop after a dog is infected with papillomavirus.
Treating Dog Warts
Warts generally disappear on their own within a few months as the dog develops immunity against the virus. However, there are times when veterinary treatment is necessary:
- Sometimes dog warts are so numerous, large, or located in such a way that they cause secondary symptoms like lameness, difficulty eating or drinking, or eye irritation.
- Warts may be bleed or become infected with bacteria.
- In rare cases, warts that fail to resolve on their own can turn into cancerous tumors. In general, warts that are present for more than 3-5 months should be treated.
- Dogs who are taking immunosuppressive medications or have other, serious health conditions may be unable to get rid of their warts without help.
If just a single or small number of warts is of concern, surgical removal is the treatment of choice. This can be done with a scalpel, laser, or through cryosurgery (using intense cold to destroy the wart).
Medications are often necessary when a large number of warts are causing problems for the dog. Unfortunately, it’s difficult to assess how effective these treatments are since most dog warts disappear on their own. However, the following medical therapy treatments have been tried by veterinarians:
- Interferon – an oral or injectable medication that stimulates the immune system
- Imiquimod – a topical, antiviral and antitumor medication
- Cimetidine – an oral medication that may have an effect on the immune system
- Azithromycin –treatment with this oral antibiotic appeared effective in one study
- Autogenous vaccination – crushing a few warts to release virus particles or giving a vaccine made out of a dog’s own warts can stimulate the immune system to respond against the virus
- Reduce immunosuppression – if possible, discontinue or reduce the dose of immunosuppressive drugs and more aggressively treat any diseases that are having an adverse effect on the dog’s immune system
Preventing the Spread of Dog Warts
There are a few things you can do to help protect your dog from developing warts. Obviously, do not let your dog play with or otherwise contact other dogs who have visible warts. If the protective nature of your dog’s skin is compromised (from wounds, rashes, etc.) or his immune system is not functioning normally, do not take him to areas where other dogs tend to congregate (e.g., parks, doggy day cares, and kennels.).
And if despite your best efforts your dog does develop warts, keep him isolated from other dogs until all the warts have disappeared.
Don't think warts are to blame for your dog's skin problems? Read up on bacterial skin infections in dogs and learn what signs and symptoms to look for.