Recurrent Airway Obstruction: They Don't Call It 'Heaves' Anymore

At a workshop in 2000, an international group of veterinary investigators eliminated the term chronic obstructive pulmonary disease (COPD) to technically describe the equine respiratory ailment commonly known as "heaves." They elected to instead refer to it as recurrent airway obstruction (RAO) to indicate that this respiratory condition is not the same as COPD in humans.

RAO is defined as episodes of obstructive lower airway disease triggered by exposure to hay and bedding and characterized by difficulty breathing, severe airway inflammation, a large number of neutrophils, airway hyperreactivity, and reversibility with bronchodilator treatment. Owners recognize the condition from these signs:

  •  Cough;
  •  Labored breathing;
  •  Flared nostrils at rest;
  •  Nasal discharge;
  •  Coughing up mucus;
  •  Depression;
  •  Elevated respiratory rate at rest;
  •  Exercise intolerance or poor performance;
  •  Increased movement of abdomen during breathing.

Veterinarians diagnose RAO through history, physical examination, and bloodwork. They use specific respiratory system tests if necessary (endoscopy, chest radiographs, bronchoalveolar lavage, and pulmonary function testing).

RAO is managed with a four-pronged approach: diet, environment, prescription medications, and supplements. The most important thing an owner can do is reduce the horse's exposure to organic dust. This means either removing hay completely from the horse's diet and replacing it with another source of fiber, or thoroughly soaking hay before feeding. "Heavey" horses generally do better when kept outside the barn as much as possible, as exposure to bedding, barn dust and hay from other horses can induce an episode. Corticosteroids such as dexamethasone are given to reduce inflammation, and bronchodilators such as clenbuterol are given to relax airway smooth muscle, relieving bronchospasm. Research is on the benefit of antioxidants like Vitamin C and certain herbs in the management of RAO is ongoing.

Article by Lydia F. Gray, DVM, MA, medical director/staff veterinarian for SmartPak. The next GetSmart lecture "Equine 911: When to call the vet and when to treat it yourself" will be held at the SmartPak Retail Store in Natick, Mass., on October 17, 2007. For more information and a complete presentation schedule for fall visit

About the Author

Lydia Gray, DVM, MA

Lydia Gray, DVM, is Medical Director and Staff Veterinarian for SmartPak Equine. She was previously the executive director of the Hooved Animal Humane Society in Woodstock, IL, and an Owner Education Director for the American Association of Equine Practitioners.

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