Effects of inhalation of albuterol sulphate, ipratroprium bromide and frusemide on breathing mechanics and gas exchange in healthy exercising horses.

This study is about investigating the impact of pre-exercise inhalation of certain drugs on the breathing mechanics and performance of healthy horses during exercise. It concludes that these drugs don’t have noticeable effects, as horses’ bodies naturally maximize bronchodilation during exertion.

Research Purpose and Methodology

• The study aimed to explore whether pre-exercise inhalation of a bronchodilator could better the breathing mechanics and improve the performance of healthy horses.
• The drugs tested were ipratropium bromide administered by nebulization half an hour before exercise, frusemide given two hours before exercise, and albuterol sulphate administered using a metered dose inhaler two hours prior to exercise.
• The drugs were administered independently of each other in a cross-over experiment, with a different set of horses used for each.
• The horse’s execution of incremental exercise tests was monitored, with the team observing oxygen consumption, carbon dioxide production, arterial blood gases, heart rate, and measures of breathing mechanics.

Findings of the Study

• No meaningful effects were observed on the tested variables from any of the drugs used. This includes measures like total pulmonary resistance (resistance of the airways in the lungs) and nasopharyngeal resistance (resistance of the airways in the nose and throat).
• The researchers also calculated the resistance of the lower airways, derived from the difference between the total pulmonary resistance and the nasopharyngeal resistance. These measures were unaffected as well.
• An explanation suggested by the researchers for this lack of effect is that, in healthy horses, maximal bronchodilation—a widening of the bronchi and bronchioles, to allow more airflow to the lungs—is naturally stimulated by the body’s sympathoadrenergic response to exercise. In other words, the horse’s body naturally optimizes airflow to the lungs when exercising.

Conclusion of the Research

• Due to the body’s natural mechanisms, it was concluded that pre-exercise inhalation of a bronchodilator by a healthy horse is unlikely to improve performance capacity.
• This leads to the assumption that there may be little benefit in administering these drugs to healthy exercising horses.