Description

Allergic bronchitis is the most common response by horses to allergens and may eventually progress to a condition known as "Chronic Obstructive Pulmonary Disease" or COPD. Also known as "heaves," allergic bronchitis is usually a delayed sensitivity to inhaled pollen, dust, or fungal spores and is similar to asthma and emphysema in people.

Symptoms

• Clear to white nasal discharge
• Intermittent cough progressing to a frequent, deep, non-productive cough
• Labored breathing with flared nostrils
• Exercise intolerance

Causes

Allergic bronchitis may be evident year round or may be seasonal when specific allergens are at their highest levels. When the levels of pollen, dust, fungal spores, or other inhalants reach a critical point, the allergic reaction results in the release of histamines, causing the bronchiolar muscles to spasm and produce the symptoms of the condition.

The horse then begins to cough -- a basic defense mechanism to remove unwanted pollutants from the lungs. Finally, thick mucus begins to form, making it more difficult for the horse to breath efficiently.

Symptoms of allergic bronchitis include an increased amount of thick viscous mucus that may block some of the small bronchioles or airways in the lungs. Although the air seems to enter the lungs normally, the horse has to push forcefully with the muscles of the thorax and abdomen in order to empty the lungs or exhale. This motion and the accompanying sounds have given rise to the traditional name of "heaves."

Prevention

The first step in preventing allergic bronchitis is the removal of the cause of the allergy. Clean, fresh air is a major component of bronchial health. The stable should be kept clean and dust free. Good ventilation for the stable or barn area is important. Ceiling fans and duct systems with particle filters will help circulate air and reduce respiratory irritants.

Hay, grain, and bedding are major sources of mold spores and particles in the barn air. When possible, store hay and bedding in a separate building rather than in a barn loft or area.

Using bedding other than straw or wood shavings, which are major sources of inhalant matter, is important in cutting down on allergens. Rubber matting or shredded paper dramatically cut the amount of airborne particles in the barn and stable.

Feed pellets or can be substituted for loose hay, often with very positive results. In addition, dampened or soaked hay is often recommended for horses with respiratory problems.

Stalls should be mucked out daily. Otherwise, ammonia fumes and other air pollutants become concentrated and lead to respiratory problems.

Treatment

The ideal stable for a horse with allergic bronchitis is an open field. This fresh air therapy may be all that is needed to return the horse's condition to normal. If the bronchitis is too firmly established, bronchodilator drugs may be necessary to relax the muscles in the bronchioles, enabling the horse to breathe freely. These medications will also thin mucus and speed up its removal.

The services of a veterinarian to diagnose problems thoroughly and to prescribe treatment is essential. Emphasis of treatment should always be restoring normal air flow in and out of the horse's lungs.