Oral Papillomatosis

Patty Khuly

Summary

Oral papillomatosis is the term for an unsightly viral disease in which young dogs will acquire warts (also known as papillomas) on their oral mucous membranes. This transmissible disease is the work of a virus of the family papovavirus.

Young dogs will become infected after direct contact with another infected dog’s oral papillomas, but transmission via indirect contact with items affected dogs have touched with their mouth is also possible. Unfortunately, the incubation period is at least two months long and may be as long as six months. This makes identification of the chain of transmission almost impossible in many cases.

Luckily, these viral papillomas are generally self-limiting and typically resolve over a period of weeks to months. What’s more, after the warts regress, dogs are generally considered immune to reinfection.

Note: This disease is NOT considered transmissible to humans or to other species of domesticated pets.

Symptoms and Identification

Oral papillomas are typically observed in young dogs as whitish, grayish or fleshy-colored wart-like masses on the mucous membranes of the mouth. The warts can appear as solitary lesions or as multiple warts distributed throughout the mouth. These warts, which range in size from a few millimeters to multiple centimeters in size, can appear on the lips, palate, tongue, and even on the throat of afflicted dogs.

Though unsightly, oral papillomas usually aren’t considered painful or uncomfortable. That is, not unless they interfere with chewing or swallowing or should they become infected.

Diagnosis is most often achieved through simple visual identification of wart-like masses in the mouth of a young dog. If persistent or atypical in appearance, however, surgical biopsy with full histopathology is recommended.

It may also be desirable to determine whether or not these masses are truly viral papillomas for reasons related to potential transmission to other dogs and because there has been some evidence indicating that viral papillomas can be precancerous.

Affected Breeds

Breed predisposition has not been established for viral papillomas.

Treatment

Treatment of oral papillomas isn’t considered strictly necessary as they will regress on their own, usually within a few weeks. However, it bears noting that dogs who have large numbers of oral papillomas in sensitive areas or who suffer from recurrent infections of these masses may require traditional surgical excision or cryotherapy (freezing) to remove the bulk of the warts.

The following treatments are also available:

  • Anti-viral doses of interferon have been used to treat severe cases. While this treatment is available in specialty settings, it’s considered expensive and inconsistent.
  • A new, topical medication called imiquimod is also available and is increasingly being prescribed for dogs.
  • A vaccine for dogs with oral papillomatosis can also be devised, with generally good results. Unfortunately, there is some indication that the vaccine can lead to cancer at the injection site (though only rarely).
  • The antibiotic azithromycin may be effective in the treatment of these papillomas. More research is needed to determine how effective it is and whether this method of inducing regression allows for permanent immunity.

Veterinary Cost

The cost of veterinary care for oral papillomas depends very much on whether definitive diagnosis and treatment are sought. Definitive diagnosis through simple surgical biopsy and full histopathology may cost up to $500 or more (depending on whether a specialist is employed and/or on geographic locale). Surgical treatment of the lesions, if extensive, can prove very expensive in certain cases –– up to $2,500. More often, however, surgical resection by a general practitioner can be had for $300 to $1,000.

Prevention

Prevention of myelopathy is not typically considered feasible. Restricting the breeding of dogs whose myelopathies are genetic in origin (as with DM and IVDD) is the only known means of prevention.


References

Bregman CL, Hirth RS, Sundburg JP, et al. Cutaneous neoplasms in dogs associated with canine oral papillomavirus vaccine. Vet Pathol 1987;24:477-487.

Gross TL, Ihrke PJ, Walden EJ. Epidermal tumors. In: Veterinary dermatopathology. St. Louis, Mo: Mosby-Year Book, 1992:330-350.

Harvey RG, McKeever PJ. Nodular dermatoses. In: A colour handbook of skin diseases of the dog and cat. London: Manson Publishing, 1998;57-59.

Scott DW, Miller WM, Griffin CE. Neoplastic and non-neoplastic tumors. Cutaneous papilloma. In: Muller & Kirk's small animal dermatology. 5th ed. Philadelphia, Pa: WB Saunders Co, 1995;994-999.

Watrach AM, Small E, Case MY. Canine papillomas: progression of oral papilloma to carcinoma. J Natl Cancer Inst 1970;45:915-920.