Feeding Horses with Heaves (Equine Asthma)

Heaves is a common “catch all” term used to describe different types of a non-infectious chronic respiratory disease where horses are having difficulty breathing. Heaves has also been called chronic obstructive pulmonary disease (COPD), recurrent airway obstruction (RAO), inflammatory airway disease (IAD) and many others. Briefly:

  • COPD. Classical descriptor of heaves but no longer in favor due to the differences in the types of disease.  
  • RAO. Most common term associated with the classical form of heaves. Usually observed in older horses at rest or after exercise. 
  • IAD. A type of heaves observed in younger horses, and usually only seen after bouts of exercise. 

The even newer term being used by many equine veterinarians to capture all the different forms of heaves is “equine asthma.” This captures the wide spectrum of heaves and in favor due to being so similar to human asthma. While there is no cure for heaves, management is key to ensure these horses do not suffer while leading healthy and happy lives. 

What Causes Heaves in Horses?

Heaves are caused by an allergic reaction to a variety of inhaled particles. These can be dust, mold, pollen, or other pollutants. Susceptible horses will inhale the allergen and their airways constrict making it difficult for them to breathe. This is because with the allergic reaction in the respiratory tract, thick mucus is produced, as well as a thickening of the lining of the lung and associated tissues. Not only does this make it difficult for the horse to breathe, but it also causes them to cough in trying to clear their respiratory tract. 

The most consistent sign of a horse suffering from heaves is a chronic cough. They will also display flared nostrils with nasal discharge and will be exercise intolerant.  In chronic cases, horses will lose weight due to stress. Also, with the constant strain of breathing and coughing, the abdominal muscles strengthen and may produce what is called a “heave line.” This can be seen along the lower abdomen below the rib cage. 

Poor air quality is the number one contributor to any type of heaves in horses. It most commonly manifests itself in horses kept in barns with poor ventilation. Contributing causes include:

  • Dusty or moldy hay 
  • Dusty bedding 
  • Environmental pollen or mold 
  • Summer pastures in hot and humid environments (Summer Pasture-Associated Obstructive Pulmonary Disease or SPAOPD)

Heaves differs from other types of allergic reactions in horses. This is primarily a respiratory disease caused by the inhalation of airborne particles. However, allergies will always remain a concern. Thus, you can learn more about other types of allergies in horses by reading:

It is important to remember that if you suspect your horse is suffering from heaves to discuss this with your veterinarian. While there is no cure, there are treatment options. However, management is seen as one of the most important aspects of helping your horses. 

How Can I Manage My Horse That is Suffering From Heaves?

The number one management goal for any owner that has a horse suffering from heaves is to try and eliminate the offending allergens. While it may be difficult to completely eliminate the offending particles, steps can be taken to reduce exposure. 

The most common offender for inducing an allergic reaction in horses suffering from heaves is hay. Even the highest quality hay will still have some dust and mold that can induce an allergic reaction. General tips include:

  • Purchase the highest quality hay possible with the least amount of dust and mold. 
  • If problems persist, soak, or steam the hay to reduce dust/mold. However, wet, or moist hay will develop mold over time. Thus, it is best not to leave it wet for long periods of time. 
  • Avoid feeding round bales due to higher levels of dust and mold. Additionally, horses tend to push their noses into round bales, leading to higher exposure of allergens.  
  • In extreme circumstances with persistent allergic reactions to hay, hay can be eliminated, and the horse moved to a complete feed. More information can be learned by reading our article What is a Complete Feed?

Heaves is most often observed in stalled horses. This is especially true during winter months when many horses are kept indoors due to weather extremes. Thus, management tips on reducing exposure to allergens include:

  • Ensuring the barn is well ventilated, even in winter months. 
  • Change to dust free bedding. Straw is often cited as the worst bedding for horses suffering from heaves due to high levels of dust and mold. Shredded paper, peat moss, or other dust-free options should be used. 
  • Increase turn out time for horses. Also, ensure a horse is turned out when cleaning stalls or the barn. 
  • Avoid using leaf blowers in barns and do not leave equipment or vehicles idling in a barn. 
  • Keep aisleways, riding arenas, and other areas with high foot traffic moist to reduce dust. 

For many horses that suffer from heaves, ideally, they could live out on pasture. However, for those horses that suffer heaves from seasonal pollen or SPAOPD, living out on pasture is not ideal. Especially during those times of year when the horse’s heaves can be triggered. Thus, being stalled would be more appropriate. However, the above principle of minimizing dust and other allergens in the barn should still be adhered to.  

How Can Dietary Management Help My Horse That Suffers From Heaves?

Unfortunately, there is no one clear management tool or cure for heaves. However, diet can contribute to improving a horse’s outlook with heaves. First, like all horses, horses that suffer from heaves need forage, or in those extreme circumstances a complete feed, to ensure they are receiving the fiber and nutrients they need. Second, horses should be on a high-quality concentrate feed appropriate to their life stage and use to ensure they are receiving their daily nutrient requirements.  

Depending on the concentrate feed chosen, supplemental feed may be appropriate, especially those high in the omega-3 fatty acids. Because heaves induce an allergic (inflammatory) response, diets higher in omega-3 fatty acids, especially those high in DHA, have been viewed as being beneficial. 

Research has also supported the use of supplemental omega-3 fatty acids in horses with heaves. A study published by Nogradi et al., concluded that omega 3 fatty acid supplementation improved clinical signs and removed airway obstruction in horses suffering from heaves. More work is needed, but this study does demonstrate that diet can help improve the quality of life for horses suffering from heaves. 

  • Tribute’s Natural Remedy® is a DHA omega 3 fatty acid supplement that may help alleviate allergic inflammation in horses suffering from heaves.

Take Home Message 

The most important point to remember is that if you suspect or know your horse is suffering from heaves is to discuss this with your veterinarian. They can help you with treating your horse and alleviate their clinical symptoms. Second, horses that suffer from heaves require a careful and detailed management plan. For those owners that are careful, these horses go on to live happy, productive, and healthy lives. If you are concerned with your feeding plan for your horse, please feel free to contact us for any help or advice.



Nogradi, N. et al. 2015. Omega-3 fatty acid supplementation provides an additional benefit to a low-dust diet in the management of horses with chronic lower airway inflammatory disease. J. Vet. Intern. Med. 29:299-306. 

Article By: Chris Mortensen, Ph.D.
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