A thorough physical exam is performed on horses with clinical signs of respiratory difficulty or persistent coughing. The veterinarian will listen to the chest to detect abnormal lung sounds such as wheezes or crackles. Sometimes it is helpful to place a bag over the horse's muzzle to allow the horse to re-breathe carbon dioxide, causing the animal to take deeper breaths, which make the lung sounds louder and easier to hear.
Samples of the fluid and secretions in the trachea and lungs may be taken and evaluated under the microscope. Culturing this material may reveal an underlying bacterial infection. Allergy skin testing also can be done to determine if the horse is allergic to certain insects, feeds, and plants that may cause the symptoms of COPD. The examining veterinarian may need to draw blood and submit it to a laboratory for a diagnosis, or to rule out potential causes of disease.
It is important that the caretaker or owner of the horse notice the environment that the horse is kept in, and the beginning of any clinical signs of breathing difficulty or coughing. For example, the horse may become more ill when stabled in a barn, or the symptoms may grow more severe when the animal is out to pasture during certain seasons of the year. This kind of information will help a veterinarian diagnose the cause of the allergies.
