Allergic Bronchitis

Description

Allergic bronchitis is the most common response by horses to allergens and eventually progresses to a condition known as "Chronic Obstructive Pulmonary Disease" or COPD. Also known as "heaves," it is characterized as a delayed sensitivity to inhaled allergens 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

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" for this condition.

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. 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.

Prevention

The first stage of prevention is obviously to remove the cause of the allergy. Clean, fresh air is a major component of bronchial health. Good ventilation for the stable or barn area is important. The stable should be kept clean and dust free. Straw should not be used for bedding, and hay should be monitored closely to make sure it isn't creating the problem. Feed pellets or horse nuts can be substituted for loose hay, often with very positive results.

Treatment

The ideal stable for a horse with COPD 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.