There are many causes of heavy breathing in horses. In order to determine what the potential causes are, it is important to know some basic information about the horse. Things such as age, weight and breed are all helpful factors, as well as any history of illness.
Overexertion can be ruled out if the horse is standing at rest, but in general it is easily distinguished from an underlying health issue. A horse that is over exerted from exercise will be evenly covered with sweat, will have a bright expression and normal responses. A resting pulse rate for a normal horse ranges between 38-40 beats per minute. Anything above this range could be a sign that the animal is in distress. The easiest way to check for a pulse is to use a stethoscope, usually directly behind the elbow of the horse. Using a watch with a second hand, count the number of heart beats in a fifteen second span, then multiply by four. This number is will be the pulse rate.
A horse that is breathing heavily should also be checked for a fever. The normal temperature range for a healthy horse is anywhere from 99 to 101 degrees, although this is a general range. What is normal for one horse may not be the same as another. However, if the horse has a temperature above 101.5, it should be counted as a possible sign of fever.
Causes of heavy breathing in horses can be many. One condition, called Chronic Obstructive Pulmonary Disease (also known as heaves), is quite similar to asthma in human beings. Heaves is usually a chronic and progressive disease, more common in horses that are kept in stables. Usually the trigger comes from dust in the surroundings or in the hay. Pollens and mold can also cause heaves, and it is important to maintain as clean and dust free environment as possible for a horse affected with this disease. Symptoms include coughing, increased nasal discharge, labored breathing, and if the disease progresses, the horse can develop a "heave" line along it's abdomen from labored breathing. Fever does not usually accompany a true case of heaves, so if there is a temperature it is possible that there is another cause for heavy breathing.
Fever generally indicates an underlying infection and can coincide with influenza, pneumonia, bronchial infections and other diseases. In these cases, an animal may be listless and lack an appetite altogether. Sometimes the animal may exhibit coughing and a purulent discharge.
If your horse is exhibiting any signs of respiratory distress, it is crucial to immediately contact a veterinarian in order to treat the animal most effectively. Veterinarians are specially trained to properly examine and diagnose illnesses in horses and licensed to administer medications the animal may need. Every horse owner should have some basic equine first aid knowledge in order to properly care for horses. This information can help the horse owner understand some very basic facts about horses, ultimately providing the best care to their equine friends.