Ability of bronchodilators to prevent bovine experimental respiratory distress

This cross-over trial involving 6 Blue Belgian double-muscled calves aimed to investigate whether ipratropium bromide inhaled alone or in combination with clenbuterol hydrochloride could prevent the dramatic clinical and pulmonary disturbances that are observed during an experimentally induced bronchoconstriction. Inhaled bronchodilators significantly influenced the clinical and functional responses of bovines subjected to a 5-hydroxytryptamine perfusion. However, despite a mean (standard error) wash-out period of 11.2 (3.1) and 7.5 (0.9) d after the 1st and the 2nd one-day challenges, respectively, first-order carry-over effects (ie those remaining from the previous treatment), effects of the period during which the treatment was allocated and interaction effects did not allow a definitive interpretation of overall treatment differences.