Norm Ducharme, DVM, MSc, Dipl. ACVS, recently joined the elite group of equine veterinary specialists invited to share their careers’ culminations during the Frank J. Milne State-of-the-Art lecture, held annually at the American Association of Equine Practitioners Convention. Ducharme, renowned for his work in equine upper respiratory disease diagnoses and treatments, described both tried-and-true approaches to managing upper airway disease as well as novel approaches currently under investigation. Ducharme currently holds the position of James Law Professor of Surgery in the Section of Large Animal Surgery at the Cornell University Hospital for Animals, in Ithaca, New York. He is also a staff surgeon at Cornell Ruffian Equine Specialists, in Elmont. He gave the address during the latest edition of the convention, held Dec. 3-7 in Orlando, Florida.

Ducharme began his presentation with a brief review of some important basics:

• The equine upper respiratory tract consists of all respiratory structures from the nose to the extrathoracic trachea, including the larynx and associated structures;
• Upper airway obstruction can negatively impact a horse’s athletic performance as well as quality of life; and
• Abnormal airflow patterns can result in upper respiratory noise; however, the intensity of such noises does not necessarily correlate with the degree of airway obstruction.

“Horses faced with impaired ventilation use one of three strategies to compensate: increasing the driving inspiratory pressure, uncoupling … gait and respiratory frequency, or changing the duration of inspiratory and expiratory times,” Ducharme said.

Those strategies ultimately manifest as the two leading clinical signs suggestive of upper respiratory disease: poor performance and abnormal respiratory noise