PAPILLOMAS (WARTS)

In Dogs 

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 Papillomas (Warts) in Dogs 

Certain viruses are able to cause the growth of small round skin tumors that are commonly referred to as warts. Everyone who has every seen a drawing of a fairy tale witch knows what warts look like so when the family dog develops small round skin growths, many people assume these are harmless warts. In reality, there are many types of small round skin growths and it is important for them to be examined as some such growths may not actually be innocuous viral warts. Most growths must be removed and biopsied before they can be identified, though there are some exceptions to this rule.

Dogs actually can get warts though not through the same viruses that cause human warts and often these warts have a characteristic appearance which does not require biopsy for identification.

In dogs, we do not call these growths warts; we use the more formal term viral papilloma. These are benign skin tumors caused by the canine oral papilloma virus.

What do these papillomas look like?
Papillomas (Warts) in Dogs Viral papillomas are round but often have a rough, almost jagged surface reminiscent of a sea anemone or a cauliflower. They occur usually on the lips and muzzle of a young dog (usually less than 2 years of age). Less commonly, papillomas can occur on the eyelids and even the surface of the eye or between the toes. Usually they occur in groups rather than as solitary growths.

How is this virus transmitted?
The infection is transmitted via contact with the papillomas on an infected dog. The incubation period is 1 to 2 months. This virus can only be spread among dogs. It is not contagious to other pets or to humans.

Are viral papillomas dangerous?
Not really. They should go away on their own as the dog's immune system matures and generates a response against the papilloma virus. There have been two cases published where viral papillomas progressed to malignancy but this is extremely rare and by no means the usual course of the infection. Typically, it takes 1 to 5 months for papillomas to regress with oral growths tending to regress sooner than ocular growths. Occasionally some papillomas will stay permanently.

Sometimes oral papillomas can become infected with bacteria of the mouth. Antibiotics will be needed in such cases to control the pain, swelling, and bad breath.

Treatment
In most cases, treatment is unnecessary; one simply allows the papillomas to go away on their own. Occasionally an unfortunate dog will have a huge number of tumors, so many that consuming food becomes a problem. Tumors can be surgically removed or frozen off cryogenically. Sometimes crushing several growths seems to stimulate the host's immune system to assist in the tumor regression process. In humans, anti-viral doses of interferon have been used to treat severe cases of warts and this treatment is also available for severely infected dogs. Sometimes some of the warts can be removed and made into a vaccine, which is felt to stimulate the immune system in removing the tumors, though such vaccines do not seem to be as effective as one might want. Obviously such treatments should be performed by a veterinarian; do not attempt freezing, cutting, or crushing of growths on your own.


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  Warts in Dogs

Papilloma viruses are small, doubleanded DNA viruses of the Papovaviridae family. Some mammals have several distinct papilloma viruses—humans have >20; cattle, 6; dogs, 3; and rabbits, 2. Different papilloma viruses often have considerable species, site, and histologic specificity. The virus is transmitted by direct contact, fomites, and possibly by insects. Papillomas have been reported in all domestic animals, birds, and fish. Multiple papillomas (papillomatosis) of skin or mucosal surfaces generally are seen in younger animals and are usually caused by viruses. Papillomatosis is most common in cattle, horses, and dogs. Single papillomas are more frequent in older animals, but they may not always be caused by viral infection.

When lesions are multiple, they may be sufficiently characteristic to confirm the diagnosis; however, there are many simulants of warts, and a definitive diagnosis requires identification of the virus or its cytopathic effects on individual cells—a change known as koilocytic atypia or koilocytosis.

In dogs, 3 clinical presentations of canine papilloma virus infection have been described. The first is canine mucous membrane papillomatosis, which primarily affects young dogs. It is characterized by the presence of multiple warts on oral mucous membranes from lips to (occasionally) the esophagus and on the conjunctival mucous membranes and adjacent haired skin. 

When the oral cavity is severely affected, there is interference with mastication and swallowing. A viral etiology has been clearly established for these lesions. The second presentation is cutaneous papillomas, which are indistinguishable from the warts that develop on or around mucous membranes. However, they are more frequently solitary and develop on older dogs. Cocker Spaniels and Kerry Blue Terriers may be predisposed. A definitive viral etiology has not been established, and lesions may be confused with cutaneous tags. Recently, a syndrome characterized by papillomatosis of one or more footpads has been described. Clinically, lesions appear as multiple, raised keratin horns. A viral etiology has been suggested but not proven.

The third presentation is cutaneous inverted papillomas, which have more in common clinically with intracutaneous cornifying epitheliomas. In this disease of young, mature dogs, lesions most commonly develop on the ventral abdomen where they appear as raised papulonodules with a keratotic center. Infrequently, viral papillomas in dogs may progress to invasive squamous cell carcinomas. 

Infectious papillomatosis is a self-limiting disease, although the duration of warts varies considerably. A variety of treatments have been advocated without agreement on efficacy. Surgical removal is recommended if the warts are sufficiently objectionable. However, because surgery in the early growing stage of warts may lead to recurrence and stimulation of growth, the warts should be removed when near their maximum size or when regressing. 

Affected animals may be isolated from susceptible ones, but with the long incubation period, many are likely to have been exposed before the problem is recognized. 

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| Skin Problems & Diseases | Atopic Dermatitis | Atopica | Dermatomyositis | Dermatology |
| Hot Spots | Otitis Externa | Demodicosis (Red Mange) | Breed-Related Dermatoses |
| Bacterial Diseases | Pyoderma | Colloidal Silver | Homemade Relief Remedies | Food Allergies |
| Combination D Tissue Salts Treatment | Skin General Links |

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