Papilloma Virus in Dogs and Cats

Papilloma virus can affect dogs, cats, and humans. It is a virus that produces fairly benign disease, with the primary symptom being the development of growths (papillomas) on the body. In humans, the growths produced by the papilloma virus are commonly referred to as “warts.” The most common type of papilloma virus in dogs is CPV-1. Although other strains exist, the majority of dogs who contract papilloma virus are affected by the CPV-1 strain. Cats are less affected by papilloma virus and it is often associated with cancer, however, those felines who do come into contact with the virus are commonly affected by the FcaPV2 strain. Since the papilloma virus is fairly uncommon in cats, this article will focus on its effects on dogs.

How do dogs get Canine Papilloma Virus?

Canine Papilloma Virus can trigger the development of growths (papillomas) on many parts of the body. Viral growths can appear in the mouth, on the lips and tongue, on the skin, genitals, and eyelids. The most commonly affected area of the body for the development of papillomas is the mouth and associated structures.

Young dogs, less than 2 years old, are more commonly affected by CPV-1. This is due to the fact that their immune system isn’t fully developed, which makes them more susceptible. Older dogs and dogs with compromised immune systems (due to cancer, immune-suppressive treatments, etc.) can also be affected but are at an overall lower risk.

The virus is highly contagious and is transmitted through direct contact such as greeting other dogs, from bedding, sharing toys, and eating/drinking out of the same bowls. Doggy daycare, other playgroup settings, dog parks, and community water bowls are the higher risk settings where transmission can occur. Papilloma virus is resistant to harsh conditions and can survive for long periods in the environment and outside the host. Fortunately, papilloma virus is host-specific, which means dogs cannot transmit the virus to humans and vice versa.

Papilloma virus enters the body either through soft, moistened skin or cuts and abrasions. The virus can also enter the body through tick, flea, and mosquito bites. Once a dog comes into contact with CPV-1, it can take one to two months to incubate. Usually, during the incubation period, no growths will develop, and the dog appears as their normal self.

After CPV-1 enters the body, it activates growth-promoting genes in the dog’s DNA, while simultaneously deactivating/suppressing the genes that limit cell growth and altering genes that control cell death.

Symptoms of Papilloma Virus in Dogs

As stated earlier in this article, the oral papilloma virus is the most common type seen in dogs. Wart-like growths develop in and around the mouth – at the corners of the mouth, on the lips, gums, and tongue. The papillomas can also develop on the chin, the upper palate, and at the back of the throat.

Papillomas often appear as multiple growths and can develop into clusters. They are usually round, pink, pinkish-red, or pale in color and have an irregular surface that resembles cauliflower or a cobblestone street. The growths can appear suddenly, sometimes overnight, and can go undetected (if not in a readily visible location) as the affected dog usually remains asymptomatic.

The vast majority of papilloma growths are benign and, only occasionally, lead to cancer. This doesn’t mean that complications can’t occur. Depending on the location of the papillomas, the dog can accidentally bite or chew on a growth, which can then cause bleeding and may lead to the development of secondary infection, oral swelling, or bad breath. If there are many growths clustered together, if they are larger in size or located in a more sensitive area of the mouth, the affected dog may experience difficulty grabbing or biting food with their mouth and teeth (prehension), difficulty chewing their food (mastication) or problems swallowing.

How is Canine Papilloma Virus diagnosed?

Canine Papilloma Virus is a medical condition that requires a visit to the vet. Many cases can be diagnosed by visualization and the appearance of wart-like growths.

Because of the possibility of papillomas developing into cancer (although lower risk), your vet may recommend testing, such as a fine-needle aspirate/biopsy (FNA), which is a fairly straightforward procedure. Cells are removed from the growth(s) using a needle and syringe. The cells are then transferred to microscope slides, which are sent to a pathologist for detailed analysis.

If any infected papillomas are detected at the time of exam by your vet, a course of antibiotics may be needed. You will want to make sure to prevent your dog from face rubbing or scratching at his/her face. An Elizabethan collar (cone collar) may be necessary until the condition has resolved.

Treatment Options for Dogs with Papilloma Virus Infection

Many dogs diagnosed with CPV-1 do not require treatment as the papillomas can disappear on their own, usually within 1 to 5 months. This “self-limiting” characteristic of the virus is due to the fact that as the young dog’s immune system continues to mature it will develop antibodies to the virus, thereby causing the growths to regress and disappear altogether.

When a quicker fix is preferred, medical/surgical intervention would be the next best step. A minor “surgical” approach known as a “crushing technique” is a viable option. Anecdotal evidence has shown that if several of the papillomas are crushed using a surgical instrument called a hemostat this will stimulate the immune system and lead to the disappearance of the papillomas over the following several weeks. Whereas this technique is not a “quick fix,” it can trigger a faster response than no intervention at all. I have personally used the crushing technique on many of my patients with good results. Depending on the location of the growths, light to heavier sedation may be needed to properly perform the procedure. Whether or not this technique is an option for your dog depends on how many papillomas are present, their locations, and the recommendations of your vet after a thorough physical exam has been performed.

If the decision is made between you and your vet to proceed with surgical removal, this is a very good and quick treatment option. Surgical methods would include cryosurgery (freezing) or traditional surgery by excision using a scalpel. Surgical removal of every growth isn’t always necessary. Evidence has shown, for some patients, the removal of some of the papillomas can stimulate the immune system to the point where the remaining growths would regress and disappear over time.

Other less commonly used treatment options include a type of vaccination, formulated using the actual growths themselves. Papilloma vaccination can be used for dogs experiencing severe symptoms such as the inability to swallow or difficulty breathing. The vaccination is in more of a research phase and not readily available. There is currently no vaccination to prevent CPV-1.

A drug called Interferon can be used as a treatment option, however, the drug is costly, and the results are mixed and inconsistent. A topical medication called Imiquimod has been more commonly used in humans but has recently become available for use in dogs. Imiquimod boosts the immune system’s regulation of inflammation which, in turn, helps destroy the virus.

If you detect any growths on your dog, especially if located in or around the mouth area and you suspect CPV-1 but aren’t sure what to do next, follow the link below to schedule a webchat with one of our highly skilled nurses, who will then schedule a video consultation with one of our very experienced veterinarians. You can also download the FirstVet app from the Apple App or Google Play Stores.

Read more:

Lumps and Bumps on Dogs and Cats

Common Types of Skin Tumors in Dogs

Mast Cell Tumors in Dogs

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