Nasopharyngeal Polyps in Cats

What are nasopharyngeal polyps?

Nasopharyngeal polyps are benign (non-cancerous) growths that develop in the middle ear, which is the compartment just behind the eardrum. The polyps grow down the eustachian tube (the tube that connects the middle ear to the back of the throat).

As the polyps expand, they may partially block the cavity at the back of the mouth, or they may grow through the eardrum into the ear canal. In some cases, the polyps grow in both directions.

What are the signs of nasopharyngeal polyps?

Nasopharyngeal polyps can make it harder for your cat to breathe because they partially block the flow of air. Affected cats may develop:

• A distinctive snorting sound when breathing
• Nasal discharge (clear or bloody)
• Sneezing

If the polyp has extended into the ear, signs may include: 

• Pawing at the ear
• Head shaking
• Head tilt
• Discharge from the ear
• Loss of balance (rarely)
• Unequal pupil size (rarely)

What causes nasopharyngeal polyps?

The cause of nasopharyngeal polyps is not known. Some researchers think they may occur as a response to chronic inflammation. Others think there is a link between infections and the development of polyps. Nasopharyngeal polyps are most common in young cats and frequently affect cats under one year of age, though older cats can also be affected.

How are nasopharyngeal polyps diagnosed?

Your veterinarian may be able to detect polyps in the back of the mouth during an oral examination. The polyp may be hidden behind the soft palate. However, in some cases, your veterinarian may see that something behind the soft palate is pushing it forward. Nasopharyngeal polyps that grow through the ear canal may be visible during a thorough examination of the ear canal and eardrum. Most cats must be sedated or anesthetized for a complete examination.

Radiographs (X-rays) can help identify nasopharyngeal polyps and a video endoscope may allow your veterinarian to see the polyp directly. CT (computed tomography) or MRI (magnetic resonance imaging) can help determine how far the polyp has grown. 

A biopsy (surgical removal of a representative sample of the polyp) may be taken. A veterinary pathologist examines the sample under a microscope to confirm the diagnosis.

How are nasopharyngeal polyps treated?

The most common treatment is surgery to remove as much of the polyp as possible. This surgery typically improves breathing and other clinical signs. In most cases, a small portion of the polyp remains, making recurrence common.

Some cats require a more extensive procedure called a bulla osteotomy. During this surgery, your veterinarian makes an incision in the tympanic bulla (the rounded part of the skull just behind the ear) to create an opening into the middle ear cavity. They can then remove the source of the polyp, making recurrence unlikely. 

Bulla osteotomy is the most effective treatment for preventing nasopharyngeal polyps from recurring. However, it is a major surgical procedure and complications can occur. Anti-inflammatory drugs such as corticosteroids may be used as an alternative to surgery, or to help control post-operative inflammation, which is thought to stimulate polyp growth. These drugs are much less effective at preventing recurrence. 

Your veterinarian may recommend sending the polyp for examination by a veterinary pathologist to confirm that it is not cancerous and does not contain evidence of infection.

What is the long-term outlook?

Most cats enjoy a relatively normal quality of life following standard polyp-removal surgery. While recurrence rates are high (up to 50%), many cats have few complications after surgery. In recurrent or severe cases, referral to a board-certified veterinary surgeon may be advisable. Your veterinarian will develop a treatment plan based on your cat’s individual needs.