Inhaled Corticosteroids, Management Changes Help RAO Horses

A combination of inhaled corticosteroids and environmental antigen avoidance helped horses with heaves.

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Imagine horses with recurrent airway obstruction (RAO, or more commonly heaves) wearing Darth Vader-like masks and breathing in corticosteroids every day sun, rain, or snow. That was essentially the scene at at the Université de Montréal in Quebec, Canada, during a yearlong study investigating the effect of inhaled corticosteroids (ICS) and antigen avoidance in horses with RAO.

Mathilde Leclere, DVM, PhD, Dipl. ACVIM, presented results of that study “Inhaled Corticosteroids and Antigen Avoidance in Heaves: A Yearlong Study” at the 2013 American College of Veterinary Internal Medicine Forum, held June 12-15 in Seattle, Wash.

RAO is a chronic and debilitating airway disease of the horse formerly known as chronic obstructive pulmonary disease. It describes a condition similar to asthma in humans in which the horse is seemingly unable to “catch its breath,” leading to the following clinical signs described in the’s Fact Sheet “Recurrent Airway Obstruction in Horses“:

  • Cough at the start of exercise (early stage of RAO);
  • Frequency of coughing increases;
  • Increased respiratory effort (even at rest);
  • Nasal discharge but no fever;
  • An obvious abdominal lift at the end of exhalation;
  • A heave line (a line running diagonally from the point of the hip forward to the lower edge of the ribs in the external abdominal oblique muscle caused by the persistently increased respiratory effort); and
  • Weight loss due to the difficulty of eating while trying to breathe.

Leclere’s team found ICS treatment improved the clinical signs of RAO, much like it does for human asthma, even in the face of persistent exposure to hay dust. Antigen avoidance (limited exposure to hay, dust, mold, pollen, and ammonia) also helped reduce clinical signs. But, horses got the most relief from RAO when both receiving ICS and avoiding environmental antigens

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Written by:

Michelle Anderson is the former digital managing editor at The Horse. A lifelong horse owner, Anderson competes in dressage and enjoys trail riding. She’s a Washington State University graduate and holds a bachelor’s degree in communications with a minor in business administration and extensive coursework in animal sciences. She has worked in equine publishing since 1998. She currently lives with her husband on a small horse property in Central Oregon.

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