Surgery of the Alar Folds in Horses

Upper respiratory tract (URT) disorders are common in racing and sporting horses and often result in poor performance and abnormal respiratory noise during exercise. Alar fold collapse (AFC) was first described in 1967 by Foerner in four American Saddlebred horses. Foerner also described a surgical treatment that is the foundation for today’s technique. AFC is less commonly reported relative to other URT disorders, and is potentially underdiagnosed. Standardbreds and Saddlebreds seem especially predisposed to this disorder relative to other breeds of performance horses.

During the period January 1998 to December 2013 approximately 600 horses were referred to the Norwegian School of Veterinary Science for suspected URT obstructive disorders. Four hundred and seventy-eight patients were harness racehorses, the remainder Thoroughbreds, riding horses, and ponies. Horses that were not diagnosed with an obvious “resting” endoscopic abnormality such as recurrent laryngeal neuropathy or epiglottic entrapment underwent a comprehensive, standardized dynamic evaluation of nasopharyngeal, laryngeal, and nostril regions on a high-speed treadmill. A total of 25 horses from this population were diagnosed with bilateral AFC and received alar fold (AF) resection surgery at our clinic performed by one of the 2 authors.

Alar fold collapse was diagnosed when horses had constant filling of the AFs at inhalation, and an abnormal vibrating noise at expiration during entire duration of the treadmill examination or other exercise. The diagnosis was confirmed by temporarily tying open the AFs during exercise. The noise then dramatically improved or disappeared.  [...]