Lower Airway Inflammation and Your Horse

By Wendy Mollat, DVM, DACVIM, Pilchuck Veterinary Hospital

Recent veterinary studies suggest that up to 80% of stabled horses have lower airway inflammation. Long-term resolution is dependent upon reducing exposure to inhaled allergens and irritants.

What Is Lower Airway Inflammation? > Lower airway inflammation (often referred to as “heaves”) occurs commonly in horses, and is characterized by marked non-infectious airway inflammation, coughing, increased mucus within the trachea and poor performance. Equine lower airway inflammation is classified as either Inflammatory Airway Disease (IAD) or Recurrent Airway Obstruction (RAO). While both IAD and RAO are associated with exposure to airborne allergens, dust, endotoxin and noxious gases, the two conditions have different clinical presentations:

  • Inflammatory Airway Disease occurs in all ages and breeds. Affected horses typically exhibit chronic intermittent cough, varying degrees of exercise intolerance and increased airway mucus secretion. Nasal discharge may be observed in horses less than 2 years old, but is less commonly present in the mature horse.
  • Horses with Recurrent Airway Obstruction exhibit labored breathing at rest or severe exercise intolerance, much like humans with asthma. These horses often have a well-defined “heave line” along the abdomen that develops secondary to an increased abdominal push during exhalation.

Diagnosing Lower Airway Inflammation > Diagnosis is based on clinical signs, absence of fevers, lack of a systemic inflammatory response on blood work and compatible changes in the bronchoalveolar lavage fluid. This fluid is obtained by passing a tube similar to a stomach tube down the trachea into the small airways. A small amount of saline is then infused into the airway and re-collected for analysis. In addition, lung X-rays and a transtracheal wash for bacterial culture may be recommended to rule out pneumonia or other non-inflammatory airway problems.

Long-Term Management > Effective long-term management depends largely upon environmental changes to reduce exposure to dust and other airway irritants. In many cases, short-term treatment with corticosteroid +/- bronchodilators may be necessary to get the inflammation under control.

Increasing the amount of time on pasture, soaking or steaming* hay prior to feeding, or switching to a pelleted/cubed diet can improve your horse’s environment and prevent recurrence of the inflammation and clinical signs. Don’t overlook other potential risk factors, including stall/barn cleaning, location of hay and bedding storage, and proximity of your horse’s stall to the arena. The good news? In many cases, with appropriate management and occasional medical treatment, horses with equine inflammatory airway disease frequently return to their previous level of athletic performance.

* HAYGAIN Hay Steamer Available for Rent > Soaking hay may reduce dust, but it is labor-intensive, requires a lot of water and may affect the palatability of hay. Alternatively, a complete pelleted or hay cube diet might result in expensive barn repairs! Pilchuck Veterinary Hospital offers a HAYGAIN (HG-600) hay steamer unit on a rental basis. This steamer effectively produces a dust- and mold-free hay product in about one hour. Our use of this product in-house has led to positive results. To learn more about the HAYGAIN unit or to make an appointment, please contact equine reception at Pilchuck at 360.568.3111.

This article originally appeared in the May 2013 Washington State Quarter Horse Association newsletter. 


Article added May 3, 2013.