Oral Tumors - Papillomas and Sarcoids

These notes are provided to help you understand the diagnosis or possible diagnosis of cancer in your pet. For general information on cancer in pets ask for our handout "What is Cancer". Your veterinarian may suggest certain tests to help confirm or eliminate diagnosis, and to help assess treatment options and likely outcomes. Because individual situations and responses vary, and because cancers often behave unpredictably, science can only give us a guide. However, information and understanding about tumors and their treatment in animals is improving all the time.

We understand that this can be a very worrying time. If you have any questions please do not hesitate to ask us.

What are papillomas and sarcoids?

"Oral papillomas (warts)are benign tumors of the epithelial lining of the mouth and throat."

Oral papillomas (warts)are benign tumors of the epithelial lining of the mouth and throat caused by papillomaviruses. The esophagus may also be affected in severe cases. Papillomaviruses are species-specific and are fairly site-specific but can be transmitted to the skin or eyes if the protective outer epithelium is damaged. The papillomas have a cauliflower-like appearance. The incubation period is approximately one month and recovery occurs within 2-3 months; after recovery, the pet will be immune to further infection. A few tumors that look clinically similar will be malignant cancers (squamous cell carcinoma) with invasion and destruction of the underlying bone.

Fibropapillomas have more proliferation of the connective tissue adjacent to the epithelium and resemble "sarcoids" in horses. They may be multiple in the mouths of young cats and are similar to tumors on the face which we now know are caused by a special type of papillomavirus. These tumors disappear spontaneously but occasionally recur.

"Pox viruses are not species specific."

Rarely, puppies may have contact with a sheep-pox virus that causes 'contagious pustular dermatitis' or "orf", and wart-like masses may appear in these pups. The tumors usually disappear spontaneously. Pox viruses are not species specific and this virus may infect people.

What do we know about the cause?

The reason why a particular pet may develop this, or any cancer, is not straightforward. Cancer is often the culmination of a series of circumstances that come together for the unfortunate individual.

However, these tumors are probably all associated with virus infections. Papillomaviruses cause most of these tumors, but other viruses may play a role in cats.

Why has my pet developed a papilloma or fibropapilloma?

Your pet has been infected with a virus.

Are these common tumors?

"Oral papillomas are cauliflower-like lesions that are common in young dogs."

Oral papillomas are cauliflower-like lesions that are common in young dogs. Papillomas and fibropapillomas (sarcoids) are rare in cats.

How will this cancer affect my pet?

These tumors are usually noticed as single or multiple polyp-like swellings on the gums or other parts of the mouth. Some ulcerate and bleed and they may become secondarily infected. Papillomas in the throat (pharynx) or esophagus are painful and may cause difficulty in swallowing.

How are papillomas and fibropapillomas diagnosed? 

Clinically, these masses often have a fairly typical appearance.

X-rays may be useful in differentiating them from malignant tumors such as invasive squamous cell carcinomas, because the invasive cancers will destroy adjacent bone.

What types of treatment are available?

  Since they will commonly disappear spontaneously within a few months, surgical removal is only recommended for diagnostic purposes (to ensure that the mass is a benign "wart"), or to treat a bleeding or infected growth. Removal at too early a stage may be counter-productive because the antigen from the papilloma cells (needed to stimulate protective immunity by the patient) is not produced until about a month after infection. If surgery is not performed, medication to reduce inflammation and pain may give symptomatic relief if the papilloma is causing discomfort.

Can papillomas and fibropapillomas disappear without treatment?

"These viral tumors can disappear spontaneously in healthy animals due to the activity of the body's immune system."

These viral tumors can disappear spontaneously in healthy animals due to the activity of the body's immune system. Occasionally, fibropapillomas may recur.

Papillomas are species specific-- ie. other than the rare sheep "orf" papilloma, the common ones in dogs and cats are NOT transmissable to humans. They are transmissable dog to dog or cat to cat with close contact.