Category: respiratory-problems-cats

Nasopharyngeal polyps

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.

Feline asthma

If your cat has a persistent or chronic cough thay may have asthma. Asthma is the most common cause of coughing in cats. In many cats the signs are relatively mild but it can also cause life-threatening breathing problems.

Human asthma is caused by inflammation of the airways without an infectious cause. It is likely that the airways of asthmatic cats are also permanently inflamed. These changes are present whether or not the asthmatic is showing signs of disease. The inflammation can cause swelling of the lining of the airways, and excessive secretions may be produced. The ongoing inflammation causes narrowing or blockage of the airways.

The airways of an asthmatic cat are hyper-reactive. This means that spasm of the airways occurs in response to a stimulus that should not normally cause a reaction. The ‘triggers’ causing airway spasm can be irritants like cigarette smoke or inhaled particles causing an allergic reaction, eg pollens or house dust. The combination of airway spasm, excess secretions and inflammation causes significant narrowing of the airways. Cats with a narrowed airway have reduced airflow to their lungs.

Most cats with asthma show signs of coughing (dry and non-productive), wheezing and laboured breathing. Some cats have a long history of mild cough whereas a small number of cats have severe asthmatic attacks with a sudden onset of wheezing and shortness of breath. Breathing is often particularly laboured as the cat tries to breathe out because the already narrowed airways become further collapsed. This means that air can be drawn into the lungs easily but becomes trapped there. Severely affected cats may breath through their mouth.

Your vet may suspect that your cat has feline asthma because of a typical history and clinical signs. However, a diagnosis of asthma requires a raft of diagnostic investigations – mainly to rule out other causes of respiratory disease. When listening to your cat’s chest your vet may hear wheezes and crackles. Some affected cats cough when their throat is pinched but in others, physical examination is unremarkable. X-rays are very useful in the diagnosis and assessment of an asthmatic cat. Although lung damage may be visible on the X-ray some cats with asthma have normal chest X-rays.

Collection of samples from the respiratory tract also plays an important role in the investigation of airway disease. A bronchoscope (a flexible tube which can be threaded into the airways of an anaesthetised cat) can be used to see what is going on inside the cat’s airways. However, cat’s airways are very small and it can be difficult to get a bronchoscope far into the airways. However, your vet will still be able to collect samples for analysis by passing a catheter deep into the airways. Asthma in man is usually diagnosed by pulmonary function tests (measuring how much air can be moved through the airways). The practical difficulties of this technique preclude its use for cats in clinical practice.

If the ‘trigger’ for asthma attacks can be identified you should make efforts to avoid exposing your cat to this substance. In practice this is rarely attainable. Reducing exposure to irritants, eg cigarette smoke, dusty cat litters and aerosol sprays may help to reduce your cat’s signs. Since obesity has been associated with asthma a weight control programme should be instituted if your cat is overweight.

Cats with mild signs may need no treatment. Those with moderate or severe disease require medication to reduce the severity and/or frequency of attacks. Feline asthma cannot be cured and so long-term medication is likely to be needed. If your cat has a severe asthma attack your vet may need to take it into the hospital so it can be given supplemental oxygen and injections of drugs.

The first step in control of signs is to control the underlying inflammation. Anti-inflammatory doses of steroids are usually used. Additional therapy is often necessary to achieve control and to limit the side-effects of long-term steroid administration. Drugs called bronchodilators which open (dilate) the airways, e.g. theophylline, are also beneficial. Although a number of novel treatments have been developed for use in human asthmatics none of these has been thoroughly evaluated in cats and they should not be used until the more conventional treatments have been properly explored and shown to be insufficient in an individual cat.

A recent trend in the management of feline asthma has been the introduction of inhalational treatments (steroids and bronchodilators) for cats. Inhaled medication is usually delivered to cats through a face-mask connected to a paediatric ‘spacer’ device. Although there is a training period in the use of these devices most cats come to tolerate them well. The advantages of this form of delivery are:

  1. The drug can be delivered to the correct site (airways) thus potentially reducing the dose received by the rest of the body. This is a particularly important consideration in the long-term use of steroids.
  2. It can be difficult to give tablets to cats in the long-term and many cats find the use of a face mask more acceptable. If you are given a spacer to give drugs to your cat your vet will show you the correct way to use it. The dose should be released into the spacer before placing the mask over your cat’s face – many cats become alarmed by the noise of the dose delivery. The cat is then allowed to take several breaths through the mask for around 10 seconds. Cats with severe asthma may need a low dose of steroids by mouth in addition to inhalational therapy. Bacterial infection is not common in asthma and antibiotics will not usually be prescribed.

Asthma is a life-long disease which will probably get worse with time and most severely affected cats will require lifelong monitoring and intermittent (if not continuous) treatment. However, with appropriate management most cats with asthma can have a good quality of life.