No two lungs are exactly alike—especially when it comes to equine airway disease. According to French researchers, when investigating lung conditions using bronchoalveolar lavage (BAL), ensure you’re checking both lungs in the process.

BAL is a diagnostic tool used to evaluate equine lung conditions that involves injecting a horse’s lung with sterile fluid before drawing it back out again for analysis. The current practice is to “wash” just one of the horse’s lungs. But limiting the BAL to a single lung can lead to missed diagnoses and false negatives, said Marianne Depecker, a PhD candidate at the animal physiopathology and functional pharmacology department at the University of Nantes-Angers-Le Mans, in Nantes, France. She presented study results on the topic at the French Equine Research Day, held February 28 in Paris.

“A BAL procedure will effectively represent the entire sampled lung, but one sampled lung is not representative of the other,” she said.

Depecker and colleagues performed bilateral BALs in 138 French Standardbred harness racing horses—the largest population of BAL research horses to date. Comparing samples from both lungs of each horse, they found significant differences from one lung to another within individual horses