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Oral warts in dogs
Just like children get warts more commonly than adults, papillomas in dogs are most commonly found in dogs under the age of 2. These warts are typically found on the lips and muzzles of young dogs but occasionally can occur on the skin as well. A common spot on the skin is between the toes. Canine papillomas are transmitted by the canine papilloma virus and can be passed between dogs, but not from dogs to humans. Infection with the virus occurs by sharing food and water bowls, toys or licking each other.
Papillomas in dogs generally regress within about 2 months without any treatment. Papillomas rarely cause discomfort, but if there are many warts present and treatment is recommended, there are several options. The most common options utilized are: surgical removal, cryotherapy (freezing off the warts) or an antibiotic treatment with azithromycin.
The virus is easily shared between dogs and outbreaks in daycare centers have occurred. An oral papilloma in a dog will probably prevent them from attending doggie daycare .
It is not uncommon for the canine oral papilloma virus to cause multiple papillomas. So, chances are, if you see one papilloma in the mouth of your dog, you will see a few more. Warts in dogs have a characteristic appearance: they are cauliflower-like or shaped like sea anemone with small fibria attached to their surface making them look almost furry. Luckily, most viral papillomas regress or disappear on their own within about 2 months.
Dog warts are contagious
Oral warts in dogs are contagious. The virus, canine papiloma virus, is transmitted through direct contact with a wart or by sharing toys, food, water, or by licking an infected dog. The virus requires tiny “microabrasions” on the skin or tissue of the mouth to establish an infection. Once transmitted, the incubation period before a wart appears is about 4 weeks. Although not fully understood, it is believed that subclinical infections can occur. This means we believe some dogs can be infected with the virus but have no visible warts. It is not known if dogs with subclinical infection can spread the virus. Many daycare centers will ask that a dog refrain from attending daycare while there are visible papillomas present in their mouth. An outbreak studied at a daycare facility demonstrated 25% transmission rate of oral papillomas amongst dogs in that daycare.
In most cases the lesions are mild and causes no discomfort for your dog. In very rare cases, dogs with serious underlying immune disease can have severe symptoms of viral papillomas with many many papillomas in their mouth causing difficulty eating and drinking
Getting rid of warts on dogs
A definitive diagnosis of a canine papilloma is only obtained by removing the wart surgically and submitting it for histopathology (looking at thin sections under the microscope) . This is rarely pursued as most papillomas will regress within weeks and the lesions have a characteristic appearance. If a papilloma does not regress within 3 months, then treatment is recommended.
Because these warts generally do not cause discomfort and typically regress within 2 months treatment is often not pursued. There are several approaches to treatment however. The most commonly pursued options include: surgery to remove the wart, cryotherapy to freeze off the wart, and use of an antibiotic.
Surgery: Surgery is generally reserved for dogs with many warts that may be causing oral discomfort. It requires general anesthesia so the warts can be removed with a laser or electrocautery to burn off the warts in the mouth. This approach is the most costly because anesthesia time in veterinary medicine is expensive and requires thoughtful use of injectable and gas anesthesia techniques and careful monitoring. Surgery in the mouth tends to heal quickly so recovery would be expected to be routine and without complication.
Cryotherapy: Freezing off warts may be able to be done on awake animals if the warts are not located inside the mouth. Cryotherapy can be performed with a cryotherapy pen. This is an instrument that sprays out a fine spray of liquid nitrogen. Liquid nitrogen is “painted” on the wart for about 30 seconds, and then repeated after one minute to allow the tissue to thaw once in between cycles. Freezing the warts damages the tissues of the wart at the cellular level. The wart should dry up and fall off within a few weeks.
Antiviral therapy: Antiviral doses of interferon have been used to treat severe cases of warts in dogs. However, the treatment is costly and has not yielded consistent results. Oral interferon is given daily to treat papillomas. The response is slow: 1-3 months, but can be continued if there is a good response. A Topical antiviral cream called imiquamod (Aldar) is an antiviral cream used in people for genital or anal warts. It is applied daily to every other day for 2-6 weeks. It is only available as single-use packets, but a single packet can treat many papillomas. Generally you need to purchase 12-14 packets at a time.
Antibiotic therapy: Azithromycin is an antibiotic with immune-modulating properties. A study of 17 dogs showed that of 10 dogs given azithromycin dosed at 10mg/kg daily for 10 days had spontaneous regression of their warts (oral and skin) within 10-15 days. The group that did not receive azithromycin still had their warts after 41-50 days.
Vaccination: There is no commercially available vaccine. However, an “autologous “ vaccine can be prepared from a dog’s own papilloma to treat it’s specific strain of oral papilloma virus. A recombinant vaccine prepared from a protein form the virus has been used experimentally to treat severe oral papillomas that did not respond to surgery.
Types of warts in dogs and what do warts look like on dogs?
Canine oral papillomas. These are caused by the CPV-1 strain and are by far the most common papilloma viral strain in dogs.
Cutaneous papillomas. These are caused the CPV-2 strain most often and appear as single nodules typically on the abdomen. Cutaneous papillomas have a characteristic central pore can be up to ½ to 1 inch in diameter.
Papilloma virus pigmented plaques. These are caused by “chi canine papilloma viruses” and usually affect pugs and miniature schnauzers. They are darkly pigmented, scaly, and of various sizes usually found on the belly. They typically only regress in pugs. They are capable of transforming into a malignant skin tumor.
Digital papillomas. These are caused by CPV-2 papilloma most commonly. They grow on the foot pads or between toes. They can regress just like oral papillomas within about 2 months.
While warts can have a typical appearance, it is always best to consult your veterinarian if you see something unusual growing on your dog. Chances are, your vet will tell you to monitor the wart for spontaneous regression over the next 2 months.