Abbreviated as COPD, chronic obstructive pulmonary disease is a lung disease in horses that closely resembles asthma in human beings. COPD is especially common in cold climates where horses are kept indoors for long periods of time near mouldy hay. Mature horses, usually age seven and older, that are kept stabled during the winter are most susceptible to COPD. Typically, horses suffering from COPD are allergic to the mould particles in hay dust, though pollens, chemicals and other substances can also trigger this condition.
Heaving to expel air from the lungs at the end of an exhale is often one of the first symptoms of COPD in horses, and using a stethoscope to detect wheezing can often confirm the condition. The typical breathing pattern in a COPD horse is characterised by prolonged, laboured respiration. Heaving of the abdomen caused by hypertrophy from coughing, acute attacks of laboured breathing, nasal flaring, severe coughing and development of heave lines should trigger an immediate call to your veterinarian after removing the horse from the proximity of any hay that may harbour mould spores.
Weight loss and exercise intolerance are also symptoms of COPD in horses. While there are other known causes of these symptoms, a COPD horse will have difficulty breathing as well, which creates an intolerance to exercise. The dust in hay or grain can trigger an attack. After attempting these activities and having repeated COPD attacks, a horse will most likely discontinue trying, for fear of another attack.
COPD in horses is the most common cause of intermittent coughing, which may be productive, usually during feeding and exercise. This intermittent coughing is too frequently overlooked and written off as an innocuous barn cough. A COPD horse's abdominal muscles will typically respond by assisting with expiration, which can lead to hypertrophy of these muscles. Hypertrophy of the muscles leads to classic heave lines. Wheezes from overexpanded lung fields are generated by airway restriction and may also present as crackles in the breathing. By not having a cough checked by a veterinarian, severe and irreversible lung damage can occur.
A horse with COPD may have a thick mucus nasal discharge, especially after even the mildest of exercise. Mucus accumulation in the airways is caused by an over-the-top response to dust in the barn getting into the horse's lungs. This accumulation can cause an inflammation and irritation from too much mucus being produced. Oftentimes the abundance of mucus being produced will cause the airways and lungs to close down. Once this has occurred, the horse will not get enough oxygen circulating through the body. Lack of oxygen, build-up of mucus and extreme coughing will undoubtedly hinder a horse's exercise, performance and even low-stress daily activities.