Allergic and obstructive lung diseases can affect numerous cats.  These diseases are sometimes called "feline asthma", "bronchitis", or "allergic bronchitis".  These diseases are not easy to classify and represent a variety of lung disorders.  However, they do share a common finding, and that is that these diseases are caused by "hyper-responsive" (over-reactive) or "hypersensitive" reactions of the airways.

Exposure to certain agents, or stimuli, can cause the airways to narrow.  The agents are usually direct irritants to the airways or are things which provoke an allergic response in the respiratory tract.  The end result of both of these situations is muscle spasms in the bronchi (breathing tubes), mucus buildup, and cellular material accumulation.  Many cats can also acquire secondary bacterial infections on top of the asthma.

Cats with asthma have a harder time on expiration (blowing the air out) due to the obstructive nature of the disease progress.  Over time, air may become trapped in the lungs and never be expelled.  This will then lead to emphysema in the cat.

Which cats are susceptible to asthma?

Any cat can get asthma.  However, it is usually seen in cats between the ages of 2 and 8.  Some speculate that female cats tend to get asthma more and that Siamese cats are more susceptible.

Clinical Signs of Asthma

Coughing and respiratory distress are the most commonly reported signs.  Coughing is a significant sign because very few other diseases cause coughing in cats.  Most cats will assume a squatting position with the neck extended outward during these coughing episodes.  Wheezing can also be heard with a stethoscope and in severe cases, by the owners themselves.

The Causes of Asthma

Because asthma is due to a hyper-responsive airway system, there can be many causes.  The majority of the time a cause cannot be identified; however, listed below are possible causes:

• Inhaled debris or irritant such as dust from renovations or cat litter, cigarette smoke, perfume, hairspray, carpet fresheners, laundry detergents etc.
• Pollens and molds
• Infectious agents such as viruses, bacteria and fungus.
• Parasites such as heartworms and lungworms.

How to Diagnose Asthma

Your veterinarian may run several tests in order to confirm a diagnosis of asthma.  Listed below are some tests your veterinarian may run.

1. Minimum Data Base:

This includes blood work to check your cat's complete blood cell count, kidney values, liver values, etc., a fecal analysis, and a urinalysis.  The complete blood cell count may show a high number of eosinophils which is a type of white blood cell.  A high eosinophil count can be associated with allergic diseases and parasitic diseases.  However, cats can have asthma and not have a high eosinophil count.  A stool check can look for evidence of lungworm eggs.
2. Heartworm Test:

Not every cat with asthma needs to be tested for heartworm.  However, if you live in an endemic area, your veterinarian may want to test your cat for this disease, even if you cat stays indoors.  The parasite is carried by mosquitoes and even mosquitoes can get inside your house and bite your cat.
3. Feline Leukemia Virus Test and Feline Immunodeficiency Virus Test:

These viruses can affect the immune system and overall health of your cat.  These viruses do not cause asthma, but can affect the treatment for the asthma if the cat was positive for one of these viruses.
4. Thoracic (chest) Radiographs (x-rays):

Your veterinarian will look for characteristic changes in the lung tissue that would suggest your cat has asthma.  Radiographs can also look for heart disease and other lung diseases.
5. Transtracheal Wash, Bronchoscopy, and Cytology:

Bronchoscopy is not commonly performed on cats suspected of having asthma because a transtracheal wash (TTW) is easily performed and is a great diagnostic tool.  However, your veterinarian may suggest that you cat have bronchoscopy done and will either perform the procedure at your hospital or refer you to a specialist.  Bronchoscopy offers the advantage of being able to actually view the airways with a  fiberoptic scope.  The scope can also collect fluid and mucus samples from the airways for analysis.  A TTW is where a sterile tube is inserted into your sedated cat and small amount of sterile saline is injected down into the airways.  The saline is immediately sucked back up into a sterile syringe.  The saline brings mucus and cells along with it and those samples are sent in for analysis (cytology) and culture (to check for bacterial infections).

Even with all these tests, sometimes the actual underlying cause cannot be found, but you will get a diagnosis of idiopathic (no know cause) asthma.  Most cats lead long live, even if the underlying cause is not found, by taking medication to control the asthma attacks.  If an underlying cause is found, you can reduce of even eliminate your cat's asthma by removing the offending cause (such as perfume) or treating the offending cause (such as heartworm).

Treatment for Asthma

There are numerous treatments for asthma.  Some cats need just one medication, others need several.  Again, if an underlying cause if found and ca be eliminated, that will help your cat greatly.

1. Eliminating know factors which contribute to the asthma.   Pay close attention to your cat's environment to see if the asthma attacks are connected to anything in the environment.
2. Bronchodilators.  These drugs open up the airways to allow air to move in and out more freely.  Use according to your veterinarian's instructions.  Some cats can do well with just a bronchodilator drug and no steroids.
3. Corticosteroids.  Steroids are very beneficial for decreasing inflammation, dilating the airways and decreasing mucus production.  Steroids are usually the mainstay of treatment in asthmatic cats.  Most cats respond quite favorable to steroid treatment, although it is usually a lifelong treatment.  Most cats can take the oral steroids prednisolone and do quite well.  Other cats may need stronger steroids or even an injectable long-acting steroid.  All steroids have potential side effects and a cat's bloodwork should be monitored while on steroids.
4. Disposable Inhalation Chambers.  A new way of treating cats for asthma is by letting the cat breathe in the steroids or bronchodilators rather than giving the medications orally.  Both classes of these drugs are available in metered dose inhalers (MDIs) for human patients.  The proper use of MDIs in infants and small children is very problematic and thus a chamber was developed for use in these young patients because they are unable to properly coordinate their breathing with the MDI actuation.  The chamber is a clear plastic tube with an opening at one end for insertion of the MDI, and a one-way valve at the opposite end that only allows medication to leave the chamber during inhalation.  Because of this chamber, it is now possible to treat cats in a similar manner.  The use of inhalation drugs allows dosage to the airways directly, without systemic side effects seen with oral administration of drugs.  Ask your veterinarian if your cat is a candidate for this type of treatment.

Asthma Emergencies

Unfortunately, some cats can have a respiratory crisis which require immediate treatment.  Like people, cats can die from asthma attacks.  If your cat has open mouth breathing, that is a true emergency and your cat should be taken to a veterinarian immediately.  Blue gums and tongue also constitute an emergency.  Some veterinarians will give an owner a small dose of a drug called terbutaline for the owner to use in an emergency while they are getting to a veterinary hospital.  Ask your doctor if your cat will need this.

Prognosis for  Asthmatic Cats

Overall, the majority of cats are manageable and do well with treatment.  Some cats can be "cured" if the primary cause (e.g. cigarette smoke) is known and eliminated.  All other cats must be on medications if they have frequent attacks.  Some cats may only have one or two asthma attacks a year and in these instances, your veterinarian may elect not to put your cat on life-long medications.  Discuss your options with your veterinarian.  Cats with severe asthma, frequent emergency attacks, and progressive problems with breathing may have a  poorer prognosis for long term management.  Every case is different and should be discusses with your cat's doctor.