A papilloma on a dog is a benign wart caused by the canine papillomavirus. These small, rough growths appear on the skin or inside the mouth and are one of the most common skin tumors in young dogs. Most papillomas resolve on their own within a few months as the dog’s immune system fights off the virus, but in rare cases they persist or cause problems that require treatment.
What Papillomas Look Like
Dog papillomas typically have a rough, irregular surface often described as cauliflower-like. They can appear as single growths or in clusters, and they range from tiny bumps a few millimeters across to larger masses. The color usually matches the surrounding skin or appears slightly paler, though some forms called pigmented plaques look darker.
The most common locations are inside and around the mouth (on the lips, gums, tongue, and palate), but papillomas also develop on the skin of the face, eyelids, feet, and other areas of the body. Oral papillomas tend to cluster, while skin papillomas are more often solitary. Occasionally, papillomas grow inward rather than outward, forming what’s called an inverted papilloma, which looks more like a firm raised nodule with a central pore.
How Dogs Get the Virus
Canine papillomavirus spreads through direct contact with an infected dog’s warts or through contaminated objects like shared toys, food bowls, and bedding. The virus can’t infect healthy, intact skin. It needs a small cut, scrape, or abrasion to reach the deeper skin cells where it sets up the infection. This is why dogs that roughhouse, chew on shared toys, or have minor mouth injuries are especially prone to oral papillomas.
After exposure, there’s an incubation period of roughly one to two months before any warts become visible. During this time the virus is quietly replicating inside skin cells, causing them to multiply faster than normal and eventually form the characteristic wart. It’s unclear whether dogs can spread the virus before visible warts appear, but subclinical infections (where the dog carries the virus without developing obvious growths) are believed to occur.
Which Dogs Are Most at Risk
Papillomas are especially common in dogs under one year old, whose immune systems haven’t yet encountered the virus. Puppies in social settings like daycare facilities, dog parks, and shelters face higher exposure. Young dogs often develop multiple oral papillomas at once, sometimes dozens, because their immune systems haven’t built a defense against the virus yet.
Older dogs typically have some immunity from prior exposure, but those on immunosuppressive medications or with weakened immune systems can still develop papillomas. In these dogs, the warts tend to be more persistent and widespread, and the risk of complications is higher. Certain breeds also appear predisposed to pigmented viral plaques, a specific form of papillomavirus-related skin lesion.
How Long Papillomas Last
The good news is that most dog papillomas disappear without any treatment. Oral papillomas caused by the most common viral strain typically last about four to eight weeks before the immune system clears them. The body mounts an immune response that shuts down viral replication, and the warts shrink and fall off on their own.
Skin papillomas caused by other viral strains can be more stubborn. Some persist for six months or longer before resolving. Once a dog has cleared a particular strain, it develops immunity to that strain and won’t be reinfected by it. However, at least 24 distinct types of canine papillomavirus have been identified, so a dog can potentially develop warts from a different strain later in life. After the warts are gone, the dog is no longer considered contagious.
Can Dog Warts Spread to Humans or Other Pets
Canine papillomavirus is highly species-specific. It spreads only between dogs and poses no risk to cats, other household pets, or people. The human papillomavirus (HPV) that causes warts in people is a completely different set of viruses. While one recent study detected traces of human papillomavirus genetic material in dog blood samples (raising questions for future investigation), there is no established evidence that canine papillomavirus can infect humans or that HPV causes disease in dogs. You don’t need to worry about catching warts from your dog.
When Papillomas Become a Problem
While most papillomas are harmless, they occasionally cause issues depending on their size, number, and location. Oral papillomas can interfere with eating, drinking, or swallowing if they grow large or cluster heavily inside the mouth. Warts on the feet can cause limping. Secondary bacterial infections can develop if a wart is traumatized by chewing or scratching, leading to bleeding, swelling, or discharge.
A more serious but uncommon concern is malignant transformation, where a benign papilloma progresses into squamous cell carcinoma, a type of skin cancer. In one large review examining hundreds of viral papillomas, the overall rate of malignant transformation was about 3.6%. This appears to be more likely in dogs with suppressed immune systems, including those on long-term immunosuppressive drugs. If a wart changes in appearance, grows rapidly, ulcerates, or doesn’t resolve within the expected timeframe, a biopsy can determine whether the cells have become abnormal.
How Papillomas Are Diagnosed
Veterinarians can often identify papillomas by their distinctive appearance alone, especially the classic cauliflower-textured oral warts in a young dog. When a growth looks unusual or doesn’t behave as expected, a biopsy provides a definitive answer. Under the microscope, papillomavirus-infected tissue shows telltale signs: thickened skin layers, distinctive changes in skin cells called koilocytes (cells with clear halos around their nuclei), and sometimes visible viral particles inside the cell nuclei. These features confirm that the growth is virus-driven rather than a different type of tumor.
Treatment Options
Because most papillomas resolve on their own, the standard approach is watchful waiting. For a young, otherwise healthy dog with a handful of oral warts, no treatment is typically needed. The immune system handles it within a couple of months.
Treatment becomes relevant when papillomas persist beyond the expected timeframe, cause pain or difficulty eating, or grow in locations where they’re repeatedly irritated. Several options exist:
- Surgical removal: Warts can be cut out, frozen off with cryotherapy, or destroyed with laser therapy. This is the most direct solution for isolated problem warts.
- Topical immune-stimulating cream: A prescription cream that activates the local immune response can be applied to accessible warts, though results vary and some cases show no response.
- Oral antibiotics with immune-modulating effects: Certain antibiotics have been used off-label to help stimulate the immune response against the virus, with mixed results.
- Interferon injections: These deliver immune-signaling proteins to help the body recognize and fight the virus, generally reserved for more severe or resistant cases.
In young dogs, surgical removal is rarely necessary because the immune system almost always catches up. For older or immunosuppressed dogs where warts linger, surgical excision is more commonly recommended, sometimes combined with additional therapy to prevent recurrence. The key factor in every case is whether the dog’s immune system can mount an adequate response on its own. When it can, papillomas are a self-limiting nuisance. When it can’t, veterinary intervention helps bridge the gap.