Objective—To evaluate whether bronchoalveolar lavage (BAL) alters respiratory mechanics of horses with recurrent airway obstruction (ie, heaves) over a 48-hour period.
Animals—6 horses affected with heaves.
Procedures—Horses were subjected to a complete BAL procedure, which included sedation with xylazine and butorphanol, intratracheal administration of lidocaine, and instillation and aspiration of two 250-mL boluses of saline (0.9% NaCl) solution through an endoscope (study 1). To evaluate the effects of saline solution, horses were subjected to the same procedure without saline solution instillation and aspiration (study 2). Lastly, the endoscope was similarly introduced into the lower airways, without sedation or saline instillation and aspiration (study 3). Respiratory mechanics were performed at baseline (time 0) and at 3, 6, 12, 24, and 48 hours after each procedure.
Results—In study 1, BAL induced a significant decrease in pulmonary resistance lasting up to 6 hours. This may have resulted from clearance of mucus in large airways. We also observed a significant increase in lung elastance and transpulmonary pressure at 12 hours after BAL in all 3 studies, which may be attributed to a circadian effect.
Conclusions and Clinical Relevance—Our results indicate that the temporal effects of BAL procedures on lung mechanics should be taken into account when designing research protocols involving horses with heaves. Future studies should address the immediate effects of BAL on lung function.