Prophylactic effects of sodium cromoglycate on chronic obstructive pulmonary disease in the horse.

When stabled in a controlled environment, horses effected with chronic obstructive pulmonary disease (COPD) became clinically asymptomatic in 4 to 32 days (mean [+/-sd] 9.1 +/- 4.9 days), the time being influenced most by the severity of the disease judged on maximum intrathoracic pressure change (Max delta Ppl) and the age of the animal. Sodium cromoglycate, a drug widely used for prophylaxis of allergic respiratory disease in man, was administered by inhalation to 56 COPD-affected horses. The results showed that a linear response existed between the number of successive days treatment with this drug and the duration of remission of clinical signs of COPD while horses were exposed to natural antigen (poor quality straw bedding). Sodium cromoglycate given as a single daily dose (80 mg) on one day and on 4 successive days prevented clinical signs for mean 3.6 days and mean 24.3 days, respectively. These results indicate that prophylactic treatment with inhaled sodium cromoglycate is an effective method of controlling the clinical signs of COPD.