Parker County Today December 2017 - Page 55

gases and atmospheric pollutants (ozone), and/or persistent respiratory viral infections. Chronic IAD often develops after overt viral respiratory tract infection and may result from inability of the immune system to fully eliminate viruses or bacteria from small airways. Exercise-induced pulmonary hemorrhage (EIPH) occurs in the majority of racehorses and is observed sporadically in many other sports that require strenuous exercise for short periods of time. The incidence of EIPH in racehorses is high but the cause and treatment are controversial. Horseman and track veterinarians generally believe that EIPH adversely affects performance, and one investigation demonstrated positive correlation between poor finishing position and endoscopic identification of blood in the airway. Conflicting data regarding the impact of EIPH on race performance may reflect the difficulty in defining performance and individual performance potential. Rapid acceleration to high-intensity exercise results in equally rapid increases in pulmonary arterial and capillary pressures. Pulmonary capillary pressures are suspected to exceed the capacity of the pulmonary system to maintain vascular integrity resulting in “stress failure” of capillaries and hemorrhage from the pulmonary vascular system. Some investigators believe that EIPH occurs secondary to IAD which may result in proliferation of vessels originating from the bronchial circulation. This region of new blood vessel formation may be fragile and more prone to rupture during maximal exercise. Identification of the ideal therapeutic agent for EIPH that will eliminate pulmonary hemorrhage without impairing race performance will not occur until the cause of the disease is understood. Given the universal nature of this disease in horses that maintain a high level of performance, a single agent is unlikely to completely eliminate the problem in horses that perform high-intensity exercise. Chronic obstructive pulmonary disease (COPD) is a chronic, recurrent allergic respiratory disease in horses exacerbated by exposure to molds in hay and straw. Obstruction to airflow in small airways results from bronchoconstriction, excessive mucus production, and cellular debris. Clinical manifestations of COPD range in severity from exercise intolerance to labored breathing at rest. Chronic obstructive pulmonary disease is uncommon in young racehorses; however low-grade COPD is an important cause of exercise intolerance and poor performance in middle-aged horses. The single most important principle for treatment of COPD is environmental management directed toward minimizing antigen exposure. Molds present in hay and straw are the most common source of antigen; therefore, affected horses are often successfully maintained in a pasture environment. If this is unsuccessful or infeasible, medical management may be necessary. Standard treatment regimens include anti-inflammatory therapy, bronchodilator therapy, and broad-spectrum antibiotics. Nonsteroidal anti- inflammatory drugs and antihistamines are ineffective in controlling the clinical signs of COPD. Dr. Craig Sweatt • Dr. Tom Hutchins • Dr. Stacy McLeod 8283 FM 920 • Weatherford, Texas • 817-458-3355 Small Animal •Equine •Livestock •Ambulatory Services 53