Chronic Obstructive Pulmonary Disease or COPD often is miss taken for asthma. It is usually an allergic reaction to dust that causes obstruction in the air passages in the lungs of horses. It usually affects horses that are six years of age or older, who are stabled, eat hay, and/or alive in dust-prone stables, near arenas or other dusty areas.
Initially the horse may have asthma-like symptoms, begin developing a chronic cough, wheeze during exercise and develop a shallow cough when feeding, with a resulting reduction in performance.
As the inflammatory response to environmental dusts or other causative factors such as bacterial, parasitic and viral infections develops, it leads to a narrowing of the airways within the lungs. The small airways of the lungs narrow as the smooth muscles surrounding the lung tissues begin to constrict.
As the disease progresses, mucus and exudates accumulate, making it more difficult for the horse to breathe. Even at rest, the horses, expiration will appear broken into two parts, hence the name broken wind. Once a horse has noticeable problems breathing, the problem is already severe
Because the air appears to be able to enter the lungs normally, the usual elastic recoil of the lungs is not powerful enough to push the air out again past the obstructions in the passage ways. As a result, the horse has to push forcefully with the muscles of the thorax and abdomen in order to empty the lungs.
Historically, this muscular effort gave rise to the name heaves. Over a period of time the muscles may become over-developed and it is possible to see a 'heave line' between the muscles along the lower belly.
Although no definitive cause for COPD has been determined and there continues to be some dispute about the kind of hypersensitivity that causes the disease, the biggest culprit in the development of chronic obstructive pulmonary disease appears to be poor-quality hay. If hay is poorly cured or old, dust and mold are released which the horse inhales, and over a period of time, the dust and/or mold can create an inflammation in the air passage ways.
Poor quality grains may also have mold spores and dust that the horse inhales during the eating process. Dusts and molds in bedding, pollens, dust and other irritants in the environment are also contributory causes of COPD.
Typically, a horse that has been in remission and is again exposed to dusty or moldy feeds or surroundings has a reaction within about 90 minutes, indicating that once the lung tissues are affected, the damage and sensitivity are ongoing, even during periods of remission.
The disease is rare in warm, dry climates and in areas where horses spend little time in stables. Most published evidence supports the theory that the disease is an allergic response that follows exposure to dust and molds.
Other causes include toxins from the intestinal tract, viral infections, exposure to cold air and genetic predisposition, although evidence to support these theories is lacking.
Lung worm infestations sometimes mimic COPD and should be ruled out before beginning treatment.
Good stable and feeding practices can help avoid and control COPD. Make sure that any fodder and bedding is mold and dust free. Switching to pellets and alfalfa cubes will lower the dust content of the air.
Always provide plenty of fresh air in a clean environment with good ventilation through the stable. It's better to use horse blankets or rugs than it is to completely close off the stable area.
Switching to shredded paper or rubber matting for bedding may help with the problem. .If the cause of COPD is allergies, treatment will be highly individualistic which means that a veterinarian will need to run tests to determine what the allergens are, the exact type of drug, dosage, method of administration, and dose frequency.