What Causes Dog Warts? And What You Should Do About Them

Dog warts -- also called viral papillomas or fibropapillomas -- are benign skin tumors caused by a virus. While dog warts are usually not dangerous, it is important to reach a correct diagnosis with your veterinarian as what may look like a wart could actually be a more serious skin condition.  In addition, some warts cause pain and/or become infected, requiring treatment. Read on to learn what you need to know about dog warts.

Dog Wart Causes

Dog warts are caused by the canine oral papillomavirus, which is a different virus than the one that causes warts in humans. The canine oral papillomavirus is highly contagious between dogs and transmitted via direct contact with warts on an infected dog, or through direct contact with the virus in the infected dog’s environment. Typically, a dog will only pick up the virus if their skin is injured, if their immune system is compromised, or if their immune system is immature. This explains why puppies and young dogs are commonly affected.

The incubation period for the papillomavirus is 1 to 2 months, so you will only begin seeing symptoms after that time has passed.

The virus can only be spread between dogs; people and other pets are not at risk.

Dog Wart Symptoms

Viral papillomas are round but tend to have a jagged surface that resembles a cauliflower. In young dogs, they are most often seen on the lips or the muzzle, though they may also occur between the toes, on the eyelids, on the surface of the eye, or near the genitalia.

More often than not they appear in groups rather than as a solitary growth.

While most warts are painless, some may cause discomfort. For example, papillomas in the mouth may interfere with a dog’s ability to eat or chew normally, and cause drooling. Papillomas between the toes may bother the dog when they put weight on their feet, and the dog may try to lick or bite the wart, resulting in pain, bleeding, and/or a secondary infection.

Diagnosing and Treating Dog Warts

Viral papillomas are easy for a veterinarian to diagnose based on appearance alone. However if the veterinarian is uncertain about whether the growth is a wart or something else, they may take biopsy samples.

In most cases, no treatment is required, and the warts will go away on their own within 2 to 12 months. However, if the warts are ulcerated, infected, causing pain, or making it difficult for your dog to function, they may be removed. They can be removed surgically (cutting them off), cryogenically (freezing them off), with laser ablation (using radiation), or with electrosurgery/electrocautery (burning them off).

Antibiotics may also be prescribed if the warts are infected, and in some cases, antibiotics have been shown to stimulate remission. Azithromycin is a commonly prescribed antibiotic for dog warts.

Sometimes, warts are removed and made into a vaccine that can be used for prevention (for example, if there is a wart outbreak in a kennel) or as treatment. However, the use of the vaccine is still somewhat experimental and may not be appropriate for your dog’s specific situation.

In rare cases, a papilloma may develop into a malignant squamous cell carcinoma. To make sure that the warts are behaving normally and not going through any malignant changes, your veterinarian will likely schedule follow-up visits until the warts goes away.

Because the virus is so contagious, infected dogs should be separated from those that are not infected.