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Recurrent Airway Obstruction (RAO) is the term veterinarians use for what is commonly known as “heaves.” In the past, “heaves” was also known as COPD or Chronic Obstructive Pulmonary Disease, but experts now recognize that this respiratory condition in humans is not the same as the one in horses. In fact, RAO is so much more similar to asthma in people that veterinary specialists have recently introduced the term “Equine Asthma Syndrome” and include both RAO (moderate to severe asthma) and the related IAD or Inflammatory Airway Disease (mild to moderate asthma) under it.
The signs and symptoms of RAO and summer pasture-associated RAO are frequent coughing, a decreased ability to perform physical exercise (ie exercise intolerance), labored breathing at rest, and excessive mucus in the airways leading to nasal discharge. It is mainly seen in horses aged 7 years and older, may have an inherited allergic component to it, and is reversible with proper medication and management.
An initial diagnosis of RAO can usually be made based on the horse’s medical history and a physical examination. However, additional tests to rule out other conditions or monitor the horse’s response to treatment may be needed. These include:
While there is no cure for RAO, it is possible to successfully manage it using a four-pronged approach: 1) prescription medications, 2) supplements, 3) diet, and 4) environment
Corticosteroids such as dexamethasone and prednisolone (as well as the newer beclomethasone and fluticasone) treat “heaves” by reducing airway inflammation and mucus production. Bronchodilators—which include clenbuterol and albuterol--are also important in treatment as they relieve airway obstruction and spasm.
Dry hay and dusty bedding are the cause of most of the small particles that get into a horse’s airway, as both are directly in the horse’s “breathing zone” and both contain high levels of reactive dust and allergens.
Steaming or wetting hay—or feeding bagged chopped hay, hay cubes, or pellets—is often recommended to reduce the dusts and molds in hay that can trigger an episode of “heaves.” Completely replacing hay with another fiber source such as a complete feed is an additional option.
For horses with “heaves” that live inside, good ventilation is vital, especially in the winter when many barns are closed up. If horses must be stalled, dust-free bedding should be used such as specially treated wood shavings, shredded paper or cardboard, peat moss, or other materials. Straw is a particularly poor type of bedding for these horses. Ideally, horses with “heaves” should be turned out as much as possible.