HORSES

Respiratory Diseases

By R. D. Scoggins.

The principal use for most horses is related to their athletic ability. This necessitates physical soundness, with horses traditionally sound in "wind and limb". Any disease that affects the respiratory system may potentially interfere with the horse's soundness of wind.

Even animals used very little physically or only for breeding need to be free of respiratory disease. Horses not worked, but kept only as pets, may cause their owners distress if chronic respiratory disease causes the horse apparent difficulty.

A number of disease conditions may interfere with respiratory health. Respiratory disease can affect horses of any age, and chronic problems may seriously reduce the usefulness of horses at maturity.

Respiratory diseases may be due to infectious agents, mechanical problems, allergic responses, or a combination of these. Mechanical problems may create breathing difficulties for horses, while bacterial, viral and allergy producing agents can all cause respiratory disease.

Respiratory disease reduces usefulness of the affected animal, since the horse is unable to tolerate vigorous exercise. A discussion of some of the more frequently seen problems of the respiratory system follows.

Sinusitis. In this condition, sinuses of the horse's head become inflamed. Causes include infectious agents, mechanical problems, and tumors.

Sinusitis rarely is a contagious disease unless it is caused by a specific virus or bacteria. The person who cares for the horse may notice a discharge from one or both nostrils. It may be quite thick in consistency and tinged with blood, and frequently has a strong unpleasant odor. Occasionally, the side of the horse's face may appear swollen. There are no geographical limitations to the occurrence of sinusitis.

Veterinarians diagnose sinusitis by physical examination, cultures of the discharges, x ray examination, and sometimes by surgery accompanied by biopsy or the removal of a small piece of the involved tissue.

Prevention includes periodic examinations for apparent abnormalities, an active immunization program to prevent infectious diseases, and periodic dental exams to prevent tooth disease from affecting the sinuses.

Palate Elongation. With this mechanical condition the soft portion of the roof of the mouth extends too far back into the upper throat or pharynx, where it may interfere with breathing during strenuous exercise. Veterinarians diagnose the condition by examining the horse's throat with an endoscope, a flexible instrument with lights that allows them to look into body cavities or spaces.

Horses cannot breathe through their mouths due to the physical design of their pharynx. Elongation of the soft palate reduces normal airflow to the point that horses are unable to tolerate hard exercise.

Because this is a developmental problem of the horse's anatomy, there is no effective prevention. Treatment consists of surgically removing the excess portion of the palate.

Bleeders

EIPH Exercise Induced Pulmonary Hemorrhage (or bleeding) is a serious condition in equine athletes. Racehorses are most frequently affected. The more strenuous the exercise, the more frequently bleeding occurs. Some studies indicate that over 60 percent of horses being raced may exhibit some degree of bleeding after racing.

The hemorrhage occurs from minute vessels in the lungs. Although seldom fatal, bleeding can interfere with the horse's breathing and result in what appears to be choking or difficulty in obtaining air.

Since blood does not always appear at the nostrils, owners may not be aware that bleeding is occurring. Some horses show visible blood when they lower their head and blood flows from the nostril.

Considerable controversy surrounds the origin and treatment of bleeders. Diuretics have been utilized with mixed success. Some hormonal therapy has been attempted using conjugated estrogens. Use of various types of fumes to "smoke" a horse's head had some temporary popularity among horsemen.

Various other chemical agents have been used unsuccessfully to prevent EPIH.

Proponents of interval training suggest that more rigorous conditioning programs resulting in horses in better physical condition would reduce EPIH. Considerable research is needed to determine the specific cause of bleeding among equine athletes.

"Heaves"

Allergic equine respiratory disease is primarily seen clinically as a condition termed "heaves" by horsemen or pulmonary emphysema by veterinarians.

This resembles asthma or emphysema in humans. It has several components of its clinical condition including reduced exercise tolerance, a frequent soft cough, a distinct push with the abdominal muscles when air is being expelled, and a crackling or squeaking sound over the lung fields when listened to with a stethoscope.

The condition frequently follows a bout of respiratory disease accompanied by severe coughing. It sometimes appears suddenly with severe respiratory distress in bronchial asthma-like attacks. The condition usually is progressive. It frequently is associated with feeding of roughage that contains a high content of dust, pollen or mold spores.

Preventive steps include a vigorous vaccination program against infectious respiratory disease, along with prompt treatment and adequate rest until complete recovery occurs from any attack of respiratory disease. Avoid feeds with dust, pollen or mold. Allow horses to live in a fresh air environment as much as possible.