Nasopharyngeal polyps are not common but they can cause significant distress to affected cats. A polyp grows from a small stalk but can become quite a substantial size. Nasopharyngeal polyps can grow into the back of the throat obstructing the breathing passageways. Signs such as sneezing and difficulty breathing are common. Surgical removal of the polyp can provide a complete cure.
Nasopharyngeal polyps grow from the Eustachian tube (a tube connecting the ear with the throat) and can grow into the back of the throat obstructing the breathing passageways. They are benign growths, i.e. they may increase in size but do not invade local tissues or spread elsewhere in the body. Polyps may also occur deep within the ear canal in the middle ear.
No-one really knows what causes nasopharyngeal polyps. However, some people think they may be associated with a long-standing infection in the respiratory tract or middle ear.
Kittens and young adult cats (around 18 months of age) are affected more often than older cats but cats may be affected at any age. Cats with nasopharyngeal polyps may have abnormal or noisy breathing due to obstruction of the air passages at the back of the nose and throat. Sneezing and discharges from the nose are also common. If the polyp is in the middle ear, your cat may show signs of an ear infection or problems with balance and hearing.
Some cats may have more dramatic signs such as head shaking, or have sore or discharging ears. In other cases there may be signs of nerve damage such as abnormal sizes of the pupils, drooling or drooping of the muscles of the face and some affected cats may have balance problems or be wobbly when walking.
Your vet may suspect the presence of a polyp from the signs that your cat shows. Looking down the cat’s ear with an auroscope may allow your vet to see part of the mass. However, a diagnosis can only be confirmed in an anaesthetised cat. Whilst asleep further tests will include imaging of your cat’s skull (usually with X-rays, but sometimes by CT or MRI scan) to see if the extent of the mass can be identified and, at the same time, your vet will also look at the back of your cat’s throat to see if the mass is visible there. The polyp may also be removed whilst your cat is under anaesthetic.
Polyps are removed by surgery and it is often possible to do this at the time of diagnosis, under the same anaesthetic. However if polyps are simply pulled out from the back of the throat they often recur because the root of the polyp remains in the Eustachian tube or middle ear. If this happens it may be necessary to perform a more aggressive surgery to prevent the mass growing back. This procedure is known as a bulla osteotomy and involves removing a piece of the bone of the skull just beneath the ear canal to gain access to the site where polyps form. By stripping out the lining of bone in this site the risk of polyp regrowth can be significantly reduced.
After removal the tissue should be sent to a laboratory for analysis to confirm that it is a benign polyp and not a form of cancer that can spread elsewhere in the body.
Simple removal of the polyp is a relatively minor procedure and rarely results in any significant problems. Your cat should make an excellent recovery after surgery. However, if the middle ear (bullae) is involved and a bulla osteotomy is performed the risk of complications is much higher.
In around 8 of 10 cats in which this procedure is performed there is some damage to the nerve running through the bulla. If this nerve is damaged cats develop a condition called ‘Horner’s syndrome’, but they usually only show relatively minor signs – their third eyelid will be elevated, covering the bottom half of the eye, and their pupils will be different sizes. However, given time, most of these signs will reduce or disappear completely.
Additionally about 4 out of 10 cats in which a bulla osteotomy is performed will show balance problems, particularly a head tilt, and they may be wobbly or have rapid uncontrolled movements of their eyes. Again these signs will usually settle down over time, but some cats are left with permanent, though usually mild, nerve damage.