Nutritional Management of Horses with Respiratory Disease

Robert Jacobs , Ph.D.

Research Manager, Equine Innovation

Nutritional management of horses with respiratory disease should be focused on reducing the airborne particulate that causes airway inflammation and mucous buildup. Certain strategies can be applied to dietary selection and feeding practices to help support horses with these aggravating conditions.

Respiratory disease can be a painful condition for horses and a challenging situation for horse owners to deal with. Nutritionally, there are a number of factors that can both exacerbate respiratory disease in horses as well as alleviate certain risk factors and contributing issues. While a blanket term of ‘Equine Asthma’ can sometimes be associated with these conditions, there are distinct differences in recurrent airway obstruction (RAO), sometimes referred to as heaves, and inflammatory airway disease.

In both cases, specific management and nutritional changes can help to support these horses and provide relief from the discomfort associated with the airway inflammation and mucous buildup.
  1. Forage management
  2. Concentrate selection
  3. Alterations in living conditions

Forage Management for Horses with Respiratory Disease

Regardless of the specific diagnosis, proper forage management can be critical in providing relief to the horse with respiratory disease. The overall goals when selecting forage for horses suffering from IAD, RAO, or seasonal allergies should be to reduce the particulate that may be inhaled and to reduce or eliminate exposure to molds and other allergens that may be present in forage. This may include restricting pasture access and/or selecting hay that is less dusty and with longer fibers to reduce the overall particulate count in the air. Further, ensuring that hay is tested for and is absent of any molds, mildew, or other allergens is paramount. Feeding management of hay to horses with these conditions can include soaking hay to reduce the dust; research has shown that simply wetting hay is not sufficient and that to reduce the particulate, hay must be completely submerged in water. Steaming hay utilizing a high temperature steam chamber will also reduce the particulate and microbial contamination. However, it is important that hay be steamed appropriately at a temperature no less than 200 degrees F. Homemade steamers that do not get hot enough may actually exacerbate mold and mildew growth and may become a fire hazard in the barn. Feeding horses from hay nets or pillows is not recommended, as horses are more likely to bury their faces in the net exposing them to increased particulate. For this reason, it is recommended that for horses with respiratory disease, hay be offered from a dust free surface at ground level. Forage alternatives such as pellets, cubes, or hay stretcher products, such as Purina® Impact® Hay Stretcher are additional options to reduce the airborne particulate associated with airway inflammation.

Concentrate Selection for Horses with Respiratory Disease

Similarly, to forage selection, when feeding concentrate to horses with respiratory disease, the overall goal should be to reduce the excess particulate. Selecting feeds with a recent manufacturing date and ensuring feeds are stored in climate-controlled storage will help to reduce moldy feed concerns. Feeding dust-free feeds such as a textured diet like Purina® Omolene® 200 can reduce the increased particulate associated with some pelleted feeds. Other options for reducing dust from concentrate diets are to soak the feeds in water (immediately prior to feeding to avoid mold growth), or coating of feed in oil. However, adding oil to feed will increase the overall calorie content of the diet and is not recommended if horse is obese. In cases where removal of all hay is necessary to reduce the dust and particulate, a complete feed can be utilized. Feeds such as Purina® Omolene® 400, Purina® Equine Senior®, and Purina® Equine Adult® are formulated to contain all the necessary fiber, calories, protein, and other nutrients that a horse needs without any supplemental forage when fed appropriately. Regardless of dietary selection, feeding horses from a clean pan at ground level will help to reduce unnecessary particulate inhalation from the ground.
Studies related to dietary supplementation targeted at reducing symptoms of respiratory disease are limited. It has been suggested that antioxidant supplementation, particularly Vitamins C and E and selenium, may be of some benefit to horses with heaves.1 However, the best nutritional strategy to support proper respiratory function is to provide a daily ration that meets all essential nutrient requirements.

Alterations in Living Situations for Horses with Respiratory Disease

In addition to medical treatment and nutritional modification, alterations in living conditions for horses with respiratory disease can help support these individuals. When considering bedding for stalled horses, utilization of dust-free materials such as shredded paper, straw, peat, or pelleted bedding should be explored. In many cases, removal of horses from enclosed barn living and allowing access to pasture may help reduce the overall particulate load on the horse. Horses that reside in a barn may benefit from well-ventilated stalls with hay and bedding stored far away from their stalls. Reducing the amount of birds in a barn can also remove feathers and bird dander, common causes of airway inflammation. Finally, bedding should be changed regularly for these horses and horses should be kept from reentering their stalls for at least an hour after cleaning to allow dust and other particulate to settle.


The main goal in feeding and managing horses with respiratory disease is the reduction of particulate and dust that is associated with airway inflammation. Forage should be selected appropriately and fed either soaked, steamed, or in a different form to limit the exacerbation of disease. Concentrate diets should also be soaked or coated with oil to reduce dust. Feeding complete diets such as Purina® Omolene® 400, Purina® Equine Senior®, and Purina® Equine Adult® can provide the nutrition necessary to support the needs of the horse without any forage. Finally, living conditions for these horses should be optimized to promote airflow and reduce particulate accumulation.
Kirschvink, N., L. Fiévez, V. Bougnet, et al. Effect of nutritional antioxidant supplementation on systemic and pulmonary antioxidant status, airway inflammation and lung function in heaves-affected horses. Equine Vet J. 2002; 34:705-712.

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