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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.

Your questions answered

What is asthma?

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.

 

Why do signs get worse?

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.

What are the signs of asthma?

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.

How will my vet know that my cat has asthma?

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.

What can I do to help my cat?

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.

What can my vet do to help my cat?

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, eg 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 inhaltional 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.

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