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Respiratory

RECURRENTAIRWAY OBSTRUCTION (HEAVES)

 

Recurrent airway obstruction (RAO), or “Heaves”, is a naturally occurring respiratory disease of horses. Commonly called Chronic Obstructive Pulmonary Disease (COPD), it is different from the condition we see in people. There is still much debate over the cause of this disease, but many researchers consider Heaves to be a hypersensitivity (allergic) reaction to dusts or molds commonly found in a horse’s environment.

 

Heaves is characterized by periods of constriction in the lungs caused by accumulation of mucus and white blood cells and contraction of the smooth muscle lining the airways. Horses with heaves may have a long-term, spontaneous cough and exercise intolerance. They may also have a clear to white nasal discharge and increased respiratory rate and effort. Overuse of the abdominal muscles may make a horizontal “heave line” visible along the flanks. Horses may also experience significant weight loss. Diagnosing Heaves is based on the identification of these clinical signs and a history of a seasonal disorder associated with husbandry changes such as a change in hay, increased time spent indoors, trailering, or any exposure to a dusty environment. Listening to the lungs with a stethoscope, one can hear wheezes, crackles or rattles.

 

Treatment of RAO is based on the elimination of the source of irritation. This is the most critical and often the most difficult change to implement, as dusts and molds are prevalent in most equine environments. Horses suffering from Heaves may benefit from a pelleted complete feed or hay cubes, limiting exposure to hay dust. Unless the pasture worsens the condition, horses should be kept outdoors year ‘round with a 3-walled shelter. If the horse is kept indoors, they should be stalled nearest a door or at the end of an aisle where there is maximum air flow. The bedding in their stall and those surrounding should be shredded paper, shavings, peat moss, or clay to eliminate dusts and molds. Even with careful environmental changes, many horses continue to show signs of respiratory inflammation.

 

Because stabling changes take time to implement, immediate treatment to quiet the inflammation may be necessary. This may include intravenous or oral corticosteroids, such as Dexamethasone or Prednisolone, or less effective anti-inflammatories such as Banamine ®. Equine “inhalers” are also available with drugs that open the airways, similar to those used in humans. Some horses may also require a short-term antibiotic, as the compromised airways are susceptible to respiratory infections.

 

The ability to recognize this disease in horses and implement good stable management are important components to your horse’s respiratory health. If you have questions about this article or other respiratory diseases or you think your horse may show signs of recurrent airway obstruction, please contact Thornwood Equine for more information.