Asthma is a condition marked by recurrent attacks of wheezing and difficulty breathing (dyspnea), caused by constriction of the airways as a result of hypersensitivity to various environmental stimuli. Feline asthma, also called feline allergic bronchitis or feline bronchopulmonary disease (FBD), is a syndrome in cats triggered by allergic activation of the cat's immune system, causing clinical signs of coughing, wheezing, sneezing, labored breathing and generalized respiratory distress.
Causes & Prevention
Feline asthma is triggered by an allergic reaction to some environmental allergen – which typically, but not always, is inhaled. The allergen itself can be almost anything. Common inciting causes include chemicals, cigarette or fireplace smoke, air pollution (smog, smoke from wildfires or from crop burning), carpet cleaners or other household cleaning products, perfumes (including those in deodorants or hair sprays), room/air fresheners, kitty litter, fertilizers, home remodeling products, paint, landscaping materials, pesticides, pollen, grasses, weeds and other shrubbery and animal dander (new pets, kennels or veterinary visits), among other things. Heartworm and parasitic lung infections are other common causes of feline asthma in certain geographic areas. Indoor allergens tend to be present year-round, while outdoor allergens tend to be more seasonal. Often, the exact asthmatic trigger is never identified. Exposure to the allergen causes inflammation of the airways with associated smooth muscle constriction and airway narrowing, leading to the classic signs of asthma.
Prevention of Feline Asthma
Most cases of feline asthma can be prevented by identifying and removing the inciting allergen(s) from the cat's environment. Unfortunately, this is not always possible. If removing the offending stimuli cannot be accomplished, several types of prescription drugs are available to help manage asthmatic conditions symptomatically, although medication cannot actually "prevent" the disorder.
Other names for feline asthma are chronic obstructive pulmonary disease, asthmatic bronchitis, feline lower airway disease, extrinsic asthma, eosinophilic bronchitis and immune-mediated airway disease. Feline asthma is fairly common in companion cats. Because the signs of this condition mimic those associated with several other respiratory conditions, conclusive diagnosis can only be made after extensive diagnostic assessment, including blood tests and thoracic radiographs (chest X-rays).
Symptoms & Signs
Cats, like people, commonly suffer from asthma. Feline asthma is caused by an allergic reaction which leads to inflammation of the lower airways and build-up of mucus in the lungs. The symptoms usually appear in young to middle-aged cats, but older cats can be affected as well. Extensive investigation may help to identify the asthmatic trigger, but often the underlying cause is never determined.
Symptoms of Feline
Feline asthma is a well-recognized medical disorder in domestic cats. The signs typically are episodic (they wax and wane over time), and they can be acute or chronic, mild or marked. The clinical signs of this condition usually include:
Coughing (can sound like "coughing up a hairball")
Labored breathing (dyspnea)
Abdominal press during exhalation (visible)
The signs usually are most prominent when the cat exhales and can typically be heard easily by the owner. Some affected cats also develop:
Loss of appetite (inappetence; anorexia)
In very severe cases, a cat may present with:
Rapid breathing (tachypnea)
Pale gums and other mucous membranes (inadequate oxygen intake; cyanosis)
Hunched shoulders (due to respiratory discomfort and distress)
These severe symptoms can also be seen in cats with pleural effusion and pulmonary edema, both of which typically are associated with heart failure. When the consequences of asthma become this extreme (called "status asthmaticus"), the cat needs immediate veterinary attention. Status asthmaticus is a true medical emergency.
Cats at Increased Risk
Siamese cats seem to be over represented as a breed. Parasitic lung infections are more common in the southern and mid-western United States, while heartworm is more prevalent in the South. While asthma can affect cats of any age, it tends to be seen most frequently in middle-aged cats between 2 and 8 years of age.
Diagnosis & Tests
Cats suffering from asthma often wheeze, cough, sneeze, have shortness of breath and display other signs associated with oxygen deprivation (cyanosis). As frightening as these symptoms can be to owners, they are also the primary determinants for diagnosing feline asthma.
How Feline Asthma is Diagnosed
There is no single test that will conclusively confirm whether a cat has asthma or some other respiratory condition. A diagnosis of feline asthma is made based upon a number of factors, including the cat's clinical signs, a thorough veterinary physical examination and history and ruling out other disorders that could cause or contribute to the symptoms, such as infectious pneumonia, cancer, heartworm disease or lung parasites.
The results of routine blood work (complete blood count and serum biochemistry profile) typically are normal in affected animals, although certain white blood cells called eosinophils may be elevated if heart or lung parasites are present. Other laboratory tests, such as fecal flotation and heartworm testing, may also be helpful if parasites are involved. Intradermal skin testing to identify the cause(s) of asthma has not proven promising in cats.
Thoracic radiographs (chest X-rays) are extremely important to the diagnosis of feline asthma. Chest films may show evidence of inflammatory lung damage, infection or scarring, or they may appear normal. The presence, absence or severity of radiographic changes does not necessarily correlate with the seriousness of the cat's disease. An echocardiogram can be used to evaluate the possibility of heartworm infection or other possible heart involvement. This is a non-invasive test that most cats tolerate quite well. Sedation is commonly necessary to quiet the cat for these procedures.
Other, more advanced tests that may help to confirm or rule out feline asthma include transtracheal wash (TTW), bronchoalveolar lavage (BAL) or bronchoscopy with specimen collection, and urine evaluation to assess systemic health and overall organ function. The samples obtained through TTW, BAL and/or bronchoscopy are assessed microscopically through a procedure called cytology, during which a pathologist or pathology technician analyzes the sample at a cellular level. If abnormal levels of bacteria are found, they can be cultured (grown) in the laboratory, to identify the particular bacterial species so that an appropriate antibiotic can be prescribed. Lung biopsy is also available, although it is rarely used in cats because it is so invasive and typically is not necessary. Sometimes, a positive response to medical treatment will help to confirm a diagnosis of asthma, when other tests are inconclusive. Fortunately, feline asthma typically can be treated successfully, with lifelong medical therapy.
Owners should keep notes of when their cats show clinical signs of asthma, and the nature and extent of those signs. This can be quite helpful to the attending veterinarian, especially to help establish any seasonality of exposure to inciting allergens.
Owners of asthmatic cats can take comfort from the fact that there are a number of treatments available to minimize the symptoms and consequences of this disorder. Once asthma is diagnosed, the veterinarian will try to identify the underlying cause(s) of the allergic reaction. Owners are encouraged to keep an "asthma diary," which records when the cat has an asthma attack, the severity of the attack and how long the attack lasts. While it may seem burdensome, an accurate record of a cat's asthmatic episodes can help identify their asthmatic triggers. The goals of treating feline allergic bronchitis are to stabilize respiratory function, alleviate inflammation and remove the inciting allergens from the cat's environment, if at all possible. Of course, all of these goals are designed to make the cat as comfortable as possible.
Cats with allergic bronchitis should be treated aggressively in order to minimize long-term airway inflammation and corresponding chronic bronchial damage. Cats with acute severe asthma attacks should be hospitalized until the crisis has passed. Sedation and administration of oxygen may be necessary to stabilize the animal. In emergencies, the veterinarian will probably administer one or more injectable medications to relieve acute respiratory distress.
A number of medications can help to reduce the number and severity of asthma attacks. Once the disorder becomes chronic, however, complete resolution may not be possible. The most common treatment protocol is administration of corticosteroids to reduce inflammation, together with bronchodilators to help inhibit airway constriction. These medications both can be given orally or in an inhaled form. In the past, nebulizers were used to administer inhaled medical treatments to asthmatic cats. However, nebulizers are difficult to use on animals – especially on cats. More recently, form-fitting metered-dose inhalers have become available. These inhalers are specifically designed to fit a cat's muzzle and are especially helpful to administer bronchial dilation medications in acute situations. Asthmatic cats also often benefit from periodic oral anti-histamines.
In cats with secondary bacterial infections, antibiotics that penetrate airway secretions may be recommended as well. Incorporation of antibiotic therapy usually follows evaluation and culture of airway samples. If the cat has associated heart or lung parasite involvement, medications called anthelminthics can be prescribed based on the specific parasite involved. Finally, cough suppressants are available for cats suffering from prolonged or exhausting non-productive coughs. Antihistamines and cough suppressants are used cautiously in cats, because coughing is a helpful and normal mechanism for clearing airway secretions.
Environmental and life-style changes are also important. Cats with asthma usually limit their activity level on their own. Obese cats should be placed on a calorie-restricted diet under the supervision of a veterinarian, because obesity can exacerbate the symptoms of asthma. Affected animals should be housed in a stress-free, clean, calm environment, preferably indoors, with a high-quality diet and free access to fresh water. An in-house air filter can be helpful to many asthmatic cats. Air conditioning and furnace filters should be changed regularly.
The prognosis for cats with asthma ranges from good to grave, depending on the extent of disease, frequency of attacks and response to treatment in a given individual. If the inciting allergen can be identified and avoided or removed, the prognosis is quite good. Life-long symptomatic treatment will be necessary in most other cases to enable affected cats to lead relatively normal lives, with a fair prognosis depending upon the extent of permanent damage to and scarring of lung tissue. Some cats, unfortunately, do not respond well to treatment, and they have a much more guarded prognosis.