Overview of Feline Nasopharyngeal Polyps
Nasopharyngeal polyps are benign growths that can occur in the pharynx (back of the throat), the middle ear and even perforate through the tympanic membrane (ear drum). The exact cause of nasopharyngeal polyps is uncertain. The problem occurs mainly in cats, with no known breed or sex predilection, and tends to be found in younger cats. The polyps appear to be the result of an inflammatory process and an underlying viral disease has been suggested but never proven.
Depending on the location of the polyp, the effect on the cat can be significant. In the pharynx, the polyp can interfere with breathing, eating and swallowing. In the middle ear, it can affect balance and hearing and can cause other neurological problems. In the ear canal, it can lead to a secondary bacterial infection with discharge and odor from the ear canal that will not resolve completely with antibiotics.
What to Watch For
Problems with balance
Ear infection that fails to respond to antibiotics
Diagnosis of Nasopharyngeal Polyps in Cats
Your veterinarian will take a detailed history regarding your cat, followed by a physical examination. Particular attention is paid to the inside of the mouth and down the ear. Some cats will tolerate an otoscopic (ear) examination, but most cats require sedation or anesthesia to inspect their ear canal.
Polyps in the back of the throat often sit behind the soft palate and may also require sedation or anesthesia for a proper evaluation. If your cat is going to be anesthetized for a full evaluation, plain X-rays of his or her skull can also be taken to define the pharynx and the bulla, the middle ear at the base of your cat’s skull.
A CT scan or MRI can help to visualize what is going on in the middle ear.
The final diagnosis is made when the polyp is removed and submitted to a pathologist for microscopic evaluation.
Treatment of Nasopharyngeal Polyps in Cats
Removal by plucking. The polyp at the back of the pharynx may be plucked out, but there can be a tendency for it to grow back, particularly if it has extensions into the middle ear or the ear canal. There have been some reports of success in treating the polyps by plucking and then giving the cat oral steroids, but such reports have not been published at this time.
Surgical removal. If the bulla (the middle ear) shows abnormalities on an X-ray or a CT scan, then surgery should be performed to open the bulla and remove the polyp from that location. This surgery is called a bulla osteotomy. If the polyp has passed through the ear drum, then it should be removed from this location. This may necessitate ear surgery.
Home Care and Prevention
If your cat has a bulla osteotomy to remove the polyp from the middle ear, there will be an incision, usually on the underside of the neck, which will need to be monitored for swelling redness or discharge. Use an Elizabethan collar to prevent scratching at the neck region. The stitches must be removed in 10 to 14 days.
Your veterinarian will discuss the possible side effects of a bulla osteotomy prior to the surgery. These relate to some of the nerves intimate to the surgical procedure. Damage to these nerves, particularly affecting the eye, is not uncommon but is usually transient. Generally, it does not require specific treatment.
Following surgery there is a good possibility that the polyp problem will be resolved and not recur.
Since inflammatory nasopharyngeal polyps in cats are a disease of unknown origin, there is no good way to prevent the problem from occurring. The disease is best addressed as soon as clinical signs develop, before your cat becomes weak and anorexic from the mass in the pharynx, and before the polyp grows in the middle ear to cause severe neurological problems.
In-depth Information on Feline Nasopharyngeal Polyps
Other diseases that can mimic nasopharyngeal polyps are those that can cause upper airway noise or snoring sounds when breathing, problems with balance, signs related to disorders of the middle ear, or chronic ear infection.
Bacterial infection is the most common cause of inflammation of the middle ear. An infection moves to the middle ear either through the blood system, through the eustachian tube, which is the natural connection between the pharynx and the middle ear, or through a ruptured ear drum. In the case of bacterial infection, the ear is usually painful to touch, and a discharge or a foul smell may emanate from the ear canal. However, an examination of the ear with an otoscope does not find an underlying polyp. There is no airway obstruction with an infection. An X-ray of the skull or a CT scan cannot differentiate a polyp from an infection, but treatment for both problems would most likely be the same, requiring surgery to open up the middle ear. An infection is more likely if both middle ears appear to be affected on an X-ray or a CT scan.
Tumors affecting the middle ear are uncommon. It is more likely that tumors originate in the ear canal and then invade into the middle ear. Tumors, like polyps, should be considered when an ear infection fails to respond to appropriate antibiotic treatment alone.
Tumors in the back of the pharynx can cause airway noise, snoring and difficulty eating and drinking. In cats such tumors may arise from the tonsils, e.g. tumors like lymphoma or squamous call carcinoma. Under sedation or general anesthesia these lesions look quite different from the smooth, pink fleshy growths typical of a nasopharyngeal polyp.
Your veterinarian will take a careful history asking about head shaking, scratching, pawing or rubbing the ear against objects. There will be questions about balance, walking normally or circling to one side, abnormal movement of the eyes, drooping of the eyelids or prominence of the third eyelid, difficulty judging jumps, clumsiness or falling.
Following a general physical examination your vet will look at your cat’s eyes, looking for drooping of the eyelid, small pupil size, prominent third eyelid, which may indicate damage to the nerves either within the middle ear or associated with it. The combination of drooped eyelid, eye set back in the socket, small pupil size and prominent third eyelid is called Horner’s Syndrome. It can occur in middle ear disease and is a common complication following bulla surgery, but is usually transient.
No laboratory work is specific for polyps, but it may be helpful to rule out any other diseases prior to a general anesthesia. Testing for feline leukemia and feline immunodeficiency virus would also be appropriate.
For a thorough examination of the pharynx and ear canal, sedation or anesthesia is usually required. This will allow your veterinarian not only look down the throat, but also to pull back the soft palate in order to visualize a polyp. A thorough ear examination can be performed using an otoscope to see if the tympanic membrane (ear drum) is intact or not.
Radiographs (X-rays) of the skull can be helpful and are usually obtained under general anesthesia. A particularly useful view is called an open-mouth view, which highlights the middle ear, the bullae, so that the two sides can be compared. Normally the bullae should contain air and their content should be black on a X-ray.
CT scan or MRI can be useful to define the extent of a mass within the middle ear. For example, in an older cat, other tumors may be considered. The CT or MRI allows determination of invasion into the inner ear, the pharynx and the outer ear, more clearly than regular X-rays. It should be noted that up to 25 percent of animals with middle ear disease do not have any abnormalities seen on their x-rays.
In cases in which there is no evidence of a polyp in the pharynx or in the external ear canal, that is one in which the abnormality is confined to the middle ear alone, myringotomy may be performed to sample the contents of the bulla. Under anesthesia a needle is passed through the ear drum and fluid and cells are obtained for culture and cytology. Appropriate antibiotics can be started. In the case of a primary infection, or an infection secondary to a polyp or other mass in the middle ear, this often fails to provide adequate drainage of infected material, necessitating more aggressive surgery.
When a polyp is present in the pharynx, it can carefully be plucked out, attempting to get as much of the stock as possible. Some success has been reported using this technique, together with a course of steroids.
When X-rays show changes in the bulla, after removing the polyp from the throat, a ventral bulla osteotomy may be performed. This involves shaving under the neck and incising the skin to get access to the appropriate middle ear. The bony bulla is opened and the polyp and infected tissue removed and flushed. A drain may be inserted in the skin incision for a few days.
When the polyp passes through the ear drum, it may be removed by plucking. Alternatively an ear surgery may be performed to allow better access and drainage of the external ear. One such procedure is called a lateral wall resection and is usually reserved for those cases in which outer ear changes are more significant.
Cultures are obtained at the time of surgery and tissue is submitted for evaluation by pathologists.
Home Care of Cats with Nasopharyngeal Polyps
Horner’s syndrome is common following a bulla osteotomy. Your veterinarian will likely have prepared you for this eventuality. No treatment is normally required and the problem usually resolves on its own. This may take a few days to weeks.
Facial paralysis is another possible complication following bulla surgery. In this case your cat may not blink on the affected side. This may necessitate placing drops or oil based lubricant in the eye several times a day to prevent dryness. This problem is again usually transient and will clear up in a few days to weeks.
Oral antibiotics should continue for a few weeks when your cat goes home and this may take the form of pills or drops, whichever is easiest. If culture results suggest that the antibiotic is inappropriate, your veterinarian will change the prescription.
Most cats are discharged with an Elizabethan collar to prevent them from scratching at the surgical site. This is especially important if there is a drain in place. The drain is often a piece of soft rubber tubing that passes through a hole in the skin adjacent to the incision. This area must be kept clean for a few days while discharge and fluid exits the surgical site. It can be helpful to take a cotton ball soaked in a little warm water to wipe the area around the drain clean, twice a day. The drain is usually removed within a few days following the surgery and this will be performed by your vet.
The incision should be examined daily for swelling redness or discharge. Stitches or staples must be removed in 10 to 14 days, at which point the Elizabethan collar can also be removed.