Heaves in Horses...What can you do about it?

Rodney Belgrave, D.V.M., M.S., Diplomate ACVIM

Please consult your veterinarian if your horse is exhibiting signs consistent with heaves.  Clinical signs can mimic other more potentially life threatening conditions, which should be ruled-out prior to pursuing aggressive medical therapy with corticosteroids.

Heaves, often referred to as Recurrent Airway Obstruction, is a condition that commonly affects stabled horses, especially as the wintertime approaches.  In the Southern part of the country it is  more prevalent in pastured horses during the summer.  The disease is often characterized by cough, increased expiratory effort, nostril flare, and a white to yellow nasal discharge.  In the more advanced cases, severe respiratory distress can ensue.  Heaves is likely caused by an allergic reaction to inhaled spores or dust leading to inflammation of the lower airways.  A variety of molds found in hay, along with barn dust are the most common offending allergens.  Because this disease is an allergic type reaction, subsequent episodes tyically occur with increasing severity.  As such, middle aged to older horses are most commonly affected.  The disease is most frequently seen in the wintertime, due to the fact that barns tend to be closed and their ventilation compromised.

The seasonal onset of clinical signs, along with the prior history of the patient, are often sufficient to arrive at a diagnosis.  Diagnostic procedures such as a transtracheal wash or a bronchoalveloar lavage can be usedful in establishing the severity of the condidtion.  The procedures, in addition to blood work are helpful in ruling out the presence of a secondary bacterial infection. 

Management changes are the first line of defense for the treatement of heaves.  Heaves horses should be stabled as little as possible.  Removing the horse from the stable and barn while cleaning the stall and sweeping th aisle will also minimize exposure to dust or molds is essential for the long-term management of the condition, and clinical signs may improve within 3-5 days of implementing strict environmental changes.  Since hay and straw are the primary source of molds and dust, the use of pelleted feed are good alternatives.  Corticosterioids are the mainstay of therapy for heaves.  These can be administered intravenously (dexamethasone), intramuscularly, or via inhalation (fluticasone).  These drugs help reduce the inflammation and allergic reaction in the airway.  A 2-4 week course of therapy is usually sufficient to control the contidion.  Bronchodilators are also frequently used in conjunction with corticosteroids.  Examples of bronchodialtors include clenbuterol (Ventipulmin ) and albuterol.  Albuterol is poorly absorbed when administered via the inhalant route.  Medical therapy is rendered ineffective if environmental changes are not simultaneously implemented.