Oral papillomas are benign growths caused by canine papillomavirus. Oral mucosa, mucocutaneous junctions, and skin around the lips are most frequently involved (see papilloma lesions image). Papillomatous lesions are fingerlike or filamentous projections that can appear cauliflower-like on the surface (see papilloma mucocutaneous junction image).
Courtesy of Dr. Brenda Mulherin.
Courtesy of Dr. James O. Noxon.
Papillomas are most common in juvenile and adolescent dogs and appear suddenly, with rapid growth and spread (see multiple papilloma image). In older adult dogs with multiple papillomas, an underlying immunodeficiency (eg, due to lymphoma) should be suspected.
Clinical signs are observed when lesions are multiple and start to interfere with prehension, mastication, or swallowing. Occasionally, dogs may bite on larger papillomas when chewing, causing them to bleed and become infected.
Frequently, the disease is self-limiting. Papillomas may regress spontaneously within weeks to months.
Courtesy of Dr. James O. Noxon.
If necessary, exophytic lesions can be debulked with laser-, electro-, or radiosurgery or by sharp resection. Surgical removal of one or more of the papillomas can initiate regression. The use of commercial or autogenous vaccines should be considered in very severe cases in which the dog cannot swallow or breathe normally. In addition, treatment with azithromycin (10 mg/kg, PO, every 24 hours) appears to be effective, resolving lesions in 2–3 weeks.
The self-limiting nature of the disease makes evaluation of any treatment difficult. Papillomaviruses have been rarely associated with the development of oral and cutaneous squamous cell carcinoma in dogs, and papillomaviruses may also cause cutaneous squamous cell carcinoma and basal cell carcinoma in cats.
Other wartlike lesions are benign exophytic proliferations of squamous epithelium. They are clinically indistinguishable from virus-induced papillomas but are generally slow-growing and solitary. They most commonly remain benign, and surgical removal is curative.
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Also see pet owner content regarding disorders of the mouth in dogs.
