ASTHMA AND BRONCHITIS
Obstructive and allergic lung diseases affect many cats and are sometimes called "asthma," "bronchitis," "allergic bronchitis" or "bronchial asthma." Regardless of the name, it is a common feline ailment. Unfortunately, these diseases are not easily classified and probably represent a variety of lung disorders. They do share a common finding of "hyper-responsive" or "over-reactive" airways.
When the airway of a cat is sensitive to certain stimuli, exposure to these agents leads to narrowing of the airways. The inciting agents are usually direct irritants to the airways or things that provoke an allergic response in the respiratory tract. Regardless of the cause, the end-result is the same: muscle spasms in the bronchi (breathing tubes), buildup of mucus, and accumulation of cellular material. The inability to clear the bronchi of this material leaves the cat susceptible to secondary infections.
Feline asthma is found in all areas of the world and in cats of all ages. The prevalence in the general adult cat population is about 1%. The most common symptoms in cats with asthma are wheezing and coughing. The coughing has been described as a dry, hacking cough that could be confused with gagging or retching. Most cats are misdiagnosed as having hairballs! Paroxysms of coughing occur frequently. In mildly affected cats, coughing or wheezing may occur only occasionally. A few cats with asthma are symptomatic in between acute and severe bouts of airway constriction. The most severely affected cats have daily coughing and wheezing and many bouts of airway constriction, leading to open mouth breathing and panting that can be life threatening. Without proper treatment, early reversible bronchoconstriction can progress to irreversible airway remodeling and calcification of bronchi.
How can I recognize an asthma attack in my cat?
Early symptoms may be difficult to detect. You may hear a faint wheezing, which is more audible after vigorous exercise. Your cat may seem to tire easily. Labored breathing may proceed a serious attack.
A full-blown asthma attack may at first resemble a cat trying to cough up a hairball, or possibly choking on food. However, the body posture is somewhat different. With asthma, the cat's body will be hunched lower to the ground and his neck and head will be extended out and down in an effort to clear the airway of mucous. The "gagging" may also be accompanied by a typical coughing sound, and possibly sneezing. The cat may or may not expel foamy mucous. Open mouth breathing or panting not associated with exercise in the cat is a sign of severe respiratory distress.
These serious attacks may not happen frequently, which makes it easy to write them off as "just a hairball". Actually, they can be life-threatening, and a cat in a full-blown attack should be taken to a veterinarian immediately. Even a cat showing one or two of the early symptoms should be examined. Once, diagnosed, there are things you can do to help your cat during one of these attacks.
Are some cats more likely to get asthma?
Obstructive lung disease is most common in cats from two to eight years of age. Siamese cats seem to be at higher risk for developing asthma and bronchitis. Obese and overweight cats also seem to be at greater risk for developing respiratory disorders.
What causes asthma?
As mentioned above, this group of diseases is characterized by hyper-responsive airways. The small breathing tubes called bronchi and bronchioles can react to a number of stimuli, such as:
Inhaled debris or irritants - dust from cat litter, cigarette smoke, perfume or hairspray, carpet fresheners, and perfumes in laundry detergent
1. Pollens or mold
2. Infectious agents - viruses, bacteria
3. Parasites - heartworms, lungworms
How is asthma diagnosed?
The symptoms of asthma can mimic other diseases, such as heartworm, pneumonia and congestive heart failure. A diagnosis is reached by using chest x-rays, a complete blood count, a feline heartworm test, and a technique to sample cells from the lower airways (transtracheal wash, bronchial wash, or bronchoalveolar lavage). Chest x-rays may be normal in some cats with asthma, while others will have signs of bronchial inflammation, collapse of the right middle lung lobe, and over inflation of the lungs.
The minimum diagnostic tests include a complete blood count (CBC), blood chemistries, fecal exam and urinalysis. These tests will assess the general health of the cat and may provide clues as to the underlying cause. One particular type of white blood cell, the eosinophil, is commonly associated with allergic events and may provide support for a tentative diagnosis of asthma. Also, in some cats, special tests will be performed on stool samples for evidence of lungworms.
Heartworm test - A cat experiencing the clinical signs of asthma should be tested for feline heartworm disease. The name 'heartworm disease" is a misnomer, as it mostly affects the lungs and not just the heart. Signs of heartworm disease are often mistaken for feline asthma or other respiratory diseases.
Feline leukemia and feline immunodeficiency virus tests - These tests are helpful in determining the overall health of the cat.
Thoracic radiography (chest X-ray) - Characteristic changes in the lungs are common on x-rays. Also, x-rays can be suggestive of heartworms or other types of heart and lung disease.
Bronchoscopy, cytology and airway lavage (washing) - Bronchoscopy is a procedure that allows the veterinarian to look down the airways of the anesthetized cat with a fiberoptic scope. After a visual examination of the airway is completed, the lining mucus of the bronchi may be sampled with a small brush. The mucus can be examined under a microscope (cytology). Finally, a small amount of sterile saline can be flushed into the airways to retrieve samples of material from deep in the lung. This material can be cultured for micro-organisms and can also be carefully studied under the microscope. The sediment can be evaluated for evidence of lungworms.
In some cases, an underlying cause cannot be identified, despite a complete and thorough diagnostic workup. Even when the underlying cause is not identified, many cats can achieve a reasonable quality of life with medical management.
Some owners decline the complete workup for a variety of reasons. In such cases, it may be acceptable to treat the cat with a course of corticosteroids ("cortisone" or "steroids") since most asthmatic cats respond favorably to these medications with few side effects. However, this approach may create two problems. Corticosteroids can worsen secondary bacterial infections; therefore, prophylactic antibiotics are reasonable in cases where a workup cannot be performed. Cats with heartworms often cough like cats with asthma and will respond temporarily to corticosteroids. Therefore, cats in locations where heartworms are common in dogs may be misdiagnosed as having asthma.
How is asthma treated?
Successful management of allergic lung disease employs one or more of the following therapies. Depending on the severity of your cat's lung involvement, he most likely will be treated with a combination of a daily steroid, either by inhaler or pill, and a bronchodilator for use as needed.
Avoidance - Any factors known to trigger or aggravate breathing problems should be avoided. In some cases, this may mean trying different brands of cat litter, eliminating cigarette smoke from the home, etc. The previous list (see "Causes") details some factors that should be considered. It is important to pay close attention to environmental factors that may aggravate the condition.
Bronchodilators - These drugs are used to open up the airway and allow the cat to move air more freely. They should be used faithfully and as directed to obtain maximum effect. Bronchodilators are available in pill or inhalant form.
Corticosteroids - Steroids have a beneficial effect on decreasing inflammation, dilating the airway, and decreasing mucus production. They constitute the mainstay of treatment for asthma. Steroids are available in pill, injectable, or inhalant forms.
Most asthmatics are started on an oral corticosteroid such as prednisolone. While oral therapy may be less expensive than inhaler therapy, it is suspected that inhaler therapy can do a better job and is associated with fewer long-term side effects.
The newest form of administration is with a metered dose inhaler, often Flovent, given through a special mask and spacer system called Aerokat. This system is similar to the mask and spacer system used to treat babies and small children. The advantage of aerosol steroid administration over pills and injections, is that it goes directly into the lungs, rather than throughout the body, thus there are fewer side effects.
Regardless of the type of medication used, it is important to notify your veterinarian if there is any change in your cat's condition while on asthma medication.
Emergency treatment may employ bronchodilators, oxygen, rapid-acting glucocorticoids, and epinephrine. If your cat has heart disease, the attending veterinarian should be advised since epinephrine is best avoided.
Will my cat recover?
Asthma is a chronic disease without a cure. Even well-controlled patients may experience occasional relapses. Cats with obstructive lung disease are usually manageable. Sometimes a "cure" may be achieved if a specific underlying cause can be identified and treated.
As with most feline health issues, the key to successful management of feline asthma is to know your cat well, keep your eyes and ears open for changes in breathing, give him his medications as prescribed, and get veterinary care when indicated, either routine checkups or emergency intervention.
Extreme respiratory distress constitutes an emergency and the cat should receive immediate attention.
For more information:
Cobb Emergency Veterinary Clinic (770) 424-9157
Cat Clinic of Cobb
2440 Sandy Plains Road
Marietta, Georgia 30066
Phone: (770) 973-6369 Fax: (770) 973-5772 firstname.lastname@example.org