What is asthma and feline bronchitis?
Asthma is a common respiratory condition in cats. The disease is caused by activation of inflammation in the lungs in response to irritants or allergens in the environment. The cells in the lungs respond by increased production of mucus and reversible narrowing (spasm) of the small airways. The condition is similar to the well described human form of the disease. In most cases the exact cause or trigger is unknown. A similar condition exists called chronic bronchitis. This shares many similarities with asthma. In cats with chronic bronchitis inflammation of the small airways is present however the reversible spasm is not.
What are the signs?
The signs of both conditions are similar and can vary in severity and frequency. The most common include:
- Rapid breathing/open-mouth breathing
- Increased noise or wheezing sounds when breathing
- Breathing difficulties/increased effort whilst breathing
Some cats can have a sudden life-threatening asthma attack. The signs of this would include breathing difficulties, open mouth breathing and weakness/collapse. This can happen in cats with previously diagnosed asthma or can be the first sign in some cases. Immediate veterinary attention is required in any cat with these signs at home.
How are the conditions diagnosed?
A diagnosis of asthma or chronic bronchitis is normally reached after a series of diagnostic tests. Often these are performed to exclude other causes of coughing/breathing difficulties in cats. Firstly a thorough history is taken. A physical examination is then performed. Harsh or wheezy sounds can be heard when the chest is auscultated.
In addition a combination of some or all of the following tests can be performed:
- Blood tests to assess general health and to evaluate white blood cell number and type.
- Faecal tests to check for feline lungworm infection may be performed.
- X-rays or a CT scan of the chest. In some asthmatic cats X-rays and/or CT scan can be normal. In others thickened airway walls are seen or signs of ‘over-inflation’ of the lungs. These tests are also important to rule out other causes of coughing/breathing abnormalities in cats.
- Bronchoscopy or video camera into the lungs to examine the inner lining of the airways.
- An airway wash may be performed. The fluid is then examined under the microscope to check inflammatory cell type and number and whether there is any evidence of bacteria or parasites. In addition the fluid is often cultured and a test for bacterial and/or parasitic DNA performed.
What is the treatment?
Both conditions are treated with anti-inflammatories (normally corticosteroids). Generally the medication is administered in one of three ways
- By injection: in cats which are hospitalised short-acting injectable forms of steroids may be administered, especially in patients that are experiencing breathing difficulties. Rarely long-acting injectable forms that can last between 3-6 weeks can be used in patients who cannot be given medication by mouth or inhaled medication.
- By mouth (tablet or occasionally liquid form): to begin with a higher dose is used before gradually reducing to the minimum effective dose.
- By inhalation: metered dose inhalers (MDIs) can be used as an alternative to oral medication. These are administered using a spacer device attached to a specially designed face mask for cats. Once a cat has become accustomed to the device it is normally well tolerated.
The advantage of this method of administration is that the steroids are delivered directly to the lungs and absorption to the rest of the body is minimised. This can reduce systemic side effects associated with oral steroid therapy. Further information regarding the Aerokat™ spacer device including a video demonstrating how it is used can be found on the following website: www.trudellmed.com
In addition some cats require bronchodilators which are drugs that can help to relax (or dilate) the small airways. This medication can be given by injection in patients that are hospitalised or by mouth (tablets) at home. Inhaled bronchodilators are also available.
What is the prognosis for feline asthma?
With appropriate treatment the prognosis is normally good. Many cats will require life-long therapy. Unfortunately some cats can have progressive signs despite treatment. Uncommonly in some asthmatic cats a severe attack can be fatal.
If you have any questions about your cat’s condition, or his or her treatment, please do not hesitate to contact us.