Heaves in Horses & Respiratory Health

By: Dr. Lydia Gray

SmartPak strongly encourages you to consult your veterinarian regarding specific questions about your horse's health. This information is not intended to diagnose or treat any disease, and is purely educational.

Brief Description

Recurrent Airway Obstruction (RAO), commonly referred to as “heaves”, is defined as episodes of obstructive lower airway disease in horses, triggered by exposure to hay and bedding. Signs include:

  • Coughing
  • Labored breathing
  • Flared nostrils at rest
  • Nasal discharge
  • Depression
  • Elevated respiratory rate at rest
  • Exercise intolerance or poor performance
  • “Heave line” (abnormal abdominal muscle development caused by coughing and labored breathing)

Supplements that May Lend Support

There is good evidence that some herbal supplements are beneficial to horses with “heaves”. Because the condition often occurs in older horses and places them under additional oxidative stress, antioxidants are recommended. Vitamin C in particular is being investigated for its role in neutralizing the free radicals associated with “heaves”.

Possible Diagnostic Tests

“Heaves” can usually be diagnosed 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:

  • Bloodwork
  • Endoscopy
  • Bronchoalveolar lavage (BAL)
  • Blood gas measurement
  • Chest x-rays
  • Lung biopsy
  • Lung function tests

Prescription Medications Available

Corticosteroids such as dexamethasone and prednisone are used to reduce airway inflammation, while bronchodilators such as Ventipulmin® (clenbuterol) are used to relieve airway obstruction.

Other Management Suggestions


Dust in hay is one of the worst offenders to a horse with “heaves”, so replacing hay with another fiber source such as a complete feed is often recommended. Soaked hay or hay cubes are other alternatives.


For horses with “heaves” that live inside, good ventilation is imperative, especially in the winter when most barns are closed up. If they must be stalled, dust-free bedding should be used - straw is a particularly poor type of bedding for these horses. Ideally, horses with “heaves” should be turned out as much as possible. Horses with “heaves” may be exercised, but only as much as their condition allows.

Questions to Ask Your Veterinarian

  • How long will my horse have to be on steroids and bronchodilators?
  • Why is it called RAO and not COPD anymore?
  • Can I continue to ride and show my horse if he has “heaves”?

Additional Resources

Further Reading for You

From our site:
From the SmartPak Ask the Vet Blog:
Heaves in Horses – What to do?
From The Horse Journal:
  • Chronic Cough Solutions, November 2001
  • Get on Top of Horse Allergies, June 2007
  • Knock out Allergies, April 2005
  • Managing the Horse with Heaves or COPD, March 2004
  • Stop Stable Cough as Soon as You Hear It, November 2005

Further Reading for Your Veterinarian

Courouce-Malblanc A, Forier G, Pronost S, et al. Comparison of prednisolone and dexamethasone effects in the presence of environmental control in heaves-affected horses. Vet J. 2008 Feb;175(2):217-333.

Herszberg B, Ramos-Barbon D, Tamaoka M, et al. Heaves, an asthma-like equine disease, involves airway smooth muscle remodeling. J Allergy Clin Immunol. 2006 Aug;118(2):382-388.

Anour R, Leinker S, van den Hoven R. Improvement of the lung function of horses with heaves by treatment with a botanical preparation for 14 days. Vet Rec. 2005 Dec 3;157(23):733-736.

About Dr. Lydia Gray

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