Feline Bronchial Asthma
Feline bronchial asthma is a recurring respiratory compromise occurring when lung airways constrict,
typically in response to airborne allergens (i.e.: dust, pollens, grasses, cigarette smoke, household
cleaner, etc.). Excess mucus forms, airways swell with inflammation, and the airway muscles go into
spasm leading to constriction. Airway constriction leads to:
 Inability to draw a deep breath
 Increased expiratory effort
 Intolerance to exercise
 Coughing
 Musical sighing sounds called wheezes
Not all of these signs may be observed; occasionally only a low grade, chronic cough, often mistaken
for a hairball, is the only sign observed by an owner. Although rare, one should know an acute
asthmatic crisis may arise at any time, and may represent a life-threatening event.
Is feline asthma the same as human asthma?
The feline condition was named asthma due to clinical features shared with the human disease. It
appears cats share all the diagnostic criteria used to make a diagnosis of asthma in humans. For
example, in humans, we know while actual symptoms of asthma occur in episodes, the airways of the
lung are diseased all the time. Recent scientific studies indicated feline airways also show evidence of
disease both during asthmatic episodes and asymptomatic periods.
How is a diagnosis of feline asthma made?
Due to constricted airways, the actual volume of air your animal can move in and out of his/her lungs
during each breath is reduced. There is often a great respiratory effort; the abdomen appears to be
working to push air out, and the breaths are shallow and rapid. Your cat may even breathe with its
mouth open in an effort to move the largest possible volume of air.
As many diseases may cause similar clinical signs to those seen in asthmatic patients, various
diagnostics tests are needed to confirm a diagnosis of feline bronchial asthma. Bloodwork, including a
complete blood count and biochemical profile, are needed to help rule out other systemic diseases.
Tests for feline leukemia virus (FeLV), feline immunodeficiency virus (FIV), and heartworm disease, are
run, as these infectious diseases may cause similar clinical manifestations. A fecal (aka stool) analysis is
recommended to rule out a lungworm infection, and electrocardiography (aka: ECG or EKG) is
performed to rule out heart abnormalities.
The key step toward making a diagnosis of feline asthma is obtaining a chest radiograph (aka: x-ray).
Classically, this radiograph will show air trapping, meaning small airways have constricted preventing
inspired air from being exhaled. The lungs appear larger than normal, as they are over-inflated. The
diaphragm may seem flattened due to this over-inflation. Inflammation and mucus build up within the
airways, causing their walls to appear thickened in the radiograph. However, some asthmatic cats
have normal radiographs. As such, procedures to retrieve cells from the lower respiratory tract (ie:
trans-tracheal wash; bronchoalveolar lavage) may also be required.
What is the usual treatment?
As was stated above, asthmatic patients suffer from airway constriction with inflammation and
excessive mucus production. As such, treatment is aimed at reducing the degree of airway
constriction, inflammation, and production of mucus. Various medications, including bronchodilators
(ie: medications that dilate airways) and corticosteroids (ie: medications used to decrease
inflammation) form the cornerstone of treatment for patients with feline bronchial asthma.
Other medications may be initiated for cats living with refractory asthma, and these drugs may also
allow your cat’s doctor to lower the dose of corticosteroids needed. Leukotriene antagonists, including
montelukast and zafirlukast, inhibit some of the substances that cause airway inflammation.
Cyproheptadine, an antihistamine, also has anti-inflammatory properties.
Traditionally, a majority of these medications have been given intravenously (ie: into a vein) in a
hospital or subcutaneously (ie: under the skin) at home by a pet owner. Recently, some of these drugs
have become available in inhalant forms, and thus, cats are able to receive these medications the same
way a human asthmatic does; that is, a cat can easily learn to tolerate the use of an inhaler.
Cats vary in their response and tolerance of medications; as such, it is not unusual for your pet’s doctor
to prescribe numerous medications and/or combinations thereof in an attempt to determine the best
treatment plan for your pet. Your veterinarian will discuss with you the various treatment options
available for your pet, and will demonstrate the administration of inhaled medications.
The treatment of feline bronchial asthma also involves elimination of the underlying source of allergy
(if possible). Thus, control of the home environment is very important in an effort to decrease
exposure to potential allergens. Some recommendations include:
1. Using minimally dusty cat litter
2. Avoiding aerosols and/or carpet cleaning products
3. Eliminating exposure to cigarette and/or cigar smoke
4. Minimizing exposure to wool blankets and/or carpeting
5. Keeping the environment comfortably cool
6. Minimizing stress
7. Using a HEPA filter in the home (with frequent filter changes)
Although not currently thoroughly investigated, food allergies may play a role in the development and
progression of feline bronchial asthma is some cats. These affected pets may benefit from a
“hypoallergenic” diet. Furthermore, some cats have responded positively to hyposensitizing vaccines
(aka: allergy shots) based upon the results of blood and/or intradermal skin tests. However, a
hypoallergic food trial may take up to 10 weeks to demonstrate a response, and hyposensitizing
immunotherapy may take up to one year to manifest a positive effect. Thus, until further information
becomes available, these methods of treatment are only typically considered for those cats not
responding to conventional therapies.
Feline asthma may culminate in a respiratory crisis that may become life-threatening. If your cat
begins to breathe with an open mouth, or if you see excessive abdominal movement during
respiration, you may have an emergency situation. Should you feel your cat is in need of immediate
veterinary attention, please contact us at 301-926-3300.