Asthma in Cats and Horses
I’m getting ready to go on vacation. The meeting with the new pet sitter is scheduled for tonight, and I’m starting to throw things into a suitcase. First in, as always, was my daughter’s nebulizer. She has asthma. We don’t use the nebulizer often, but it’s one of those things that you want on hand just in case. This got me to thinking about asthma in pets.
Of all companion animals, cats and horses are the most likely to suffer from diseases that are equivalent to, if not exactly the same, as human asthma. In cats, the disease is so similar that veterinarians usually do simply call it feline asthma. Allergic bronchitis is another term you might hear. In horses, the condition is a little different and may go by the name "recurrent airway obstruction (RAO)," "chronic obstructive pulmonary disease (COPD)," or "heaves."
The underlying etiology of asthma is more or less the same, no matter what species is involved. Something in the environment irritates the lining of the respiratory tract. The irritant is commonly an allergic trigger, but viruses, cold temperatures, rapid breathing due to exercise, chemicals in the air, etc., can also be to blame. Whatever the reason, the respiratory tract becomes inflamed, cells produce more mucus than normal, and airways become narrower because the muscles that surround them contract.
The symptoms of an asthma flare-up vary depending on its severity and patient individuality. A mild episode might be characterized by a short period of rapid or deep breathing, coughing, and lethargy that resolves on its own. More severe flare-ups are potentially life-threatening and can leave animals literally gasping for breath.
On physical exam, the classic sign of asthma is an expiratory wheeze (i.e., a high-pitched sound heard when the patient breathes out). In severe cases, you can hear the wheeze while just standing next to the animal, but most of the time a stethoscope is necessary. Of course, not every patient with asthma wheezes and not every wheeze is associated with asthma, so veterinarians need the results of a complete history and physical exam, and oftentimes chest X-rays, blood work, fecal exams, and other diagnostic tests to definitively diagnose asthma.
Asthma cannot be cured, but in many cases it can be managed well enough that it does not have to significantly affect a patient’s quality of life. If you can identify your pet’s triggers (e.g., cigarette smoke, air fresheners, or dusty cat litter or hay), do your best to eliminate them from its immediate environment. Medications that reduce inflammation (e.g., prednisolone, prednisone, fluticasone, beclomethasone, or dexamethasone) and dilate airways (e.g., terbutaline, theophylline, albuterol, salmeterol or clenbuterol) are the mainstays of treating asthma in pets. For long term management, medications are ideally administered as an aerosol using a mask and a spacer to reduce the potential for systemic side effects, but in some cases oral or injectable drugs are necessary. Other options for treatment include cyproheptadine, zafirlukast, montelukast, and cyclosporine.
Do you have a cat with asthma or a horse with heaves? If so, what has your experience been with the disease and its treatment?
Dr. Jennifer Coates