Heaves in Horses & Respiratory Health
By: Dr. Lydia Gray, SmartPak Medical Director/Staff VeterinarianBrief Description
Recurrent Airway Obstruction (RAO) is the term veterinarians use for what is commonly known as “heaves.” In the past, “heaves” was also known as COPD or Chronic Obstructive Pulmonary Disease, but experts now recognize that this respiratory condition in humans is not the same as the one in horses. In fact, RAO is so much more similar to asthma in people that veterinary specialists have recently introduced the term “Equine Asthma Syndrome” and include both RAO (moderate to severe asthma) and the related IAD or Inflammatory Airway Disease (mild to moderate asthma) under it.
The signs and symptoms of RAO and summer pasture-associated RAO are frequent coughing, a decreased ability to perform physical exercise (ie exercise intolerance), labored breathing at rest, and excessive mucus in the airways leading to nasal discharge. It is mainly seen in horses aged 7 years and older, may have an inherited allergic component to it, and is reversible with proper medication and management.
Possible Diagnostic Tests
An initial diagnosis of RAO can usually be made 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, obtaining cells directly from the lower airway)
- Chest x-rays
- Lung function tests
While there is no cure for RAO, it is possible to successfully manage it using a four-pronged approach: 1) prescription medications, 2) supplements, 3) diet, and 4) environment
Prescription Medications Available
Corticosteroids such as dexamethasone and prednisolone (as well as the newer beclomethasone and fluticasone) treat “heaves” by reducing airway inflammation and mucus production. Bronchodilators—which include clenbuterol and albuterol--are also important in treatment as they relieve airway obstruction and spasm.
Supplements that May Lend Support
The American College of Veterinary Internal Medicine recently published a revised consensus statement on inflammatory airway disease in horses that mentions the benefit of combining omega 3 fatty acids with other management changes. The group of horses that was supplemented with omega 3s (DHA in particular) in addition to management changes demonstrated positive results sooner than the group that underwent management changes alone.Since MSM has a long track record of safe use in the horse and has been shown to be a potent antioxidant in horses, some veterinarians routinely recommend its use in seasonal allergic conditions of the respiratory tract. Finally, because RAO may place horses under additional oxidative stress of the airway, antioxidants are recommended. Vitamin C specifically is being investigated for its role in neutralizing the excessive free radicals associated with “heaves".
Other Management Suggestions
Dry hay and dusty bedding are the cause of most of the small particles that get into a horse’s airway, as both are directly in the horse’s “breathing zone” and both contain high levels of reactive dust and allergens.
Diet
Steaming or wetting hay—or feeding bagged chopped hay, hay cubes, or pellets—is often recommended to reduce the dusts and molds in hay that can trigger an episode of “heaves.” Completely replacing hay with another fiber source such as a complete feed is an additional option.
Environment
For horses with “heaves” that live inside, good ventilation is vital, especially in the winter when many barns are closed up. If horses must be stalled, dust-free bedding should be used such as specially treated wood shavings, shredded paper or cardboard, peat moss, or other materials. Straw is a particularly poor type of bedding for these horses. Ideally, horses with “heaves” should be turned out as much as possible.
Questions to Ask Your Veterinarian
- Can I continue to ride and show my horse if he has “heaves”?
- How long will my horse have to be on steroids and bronchodilators?
- Will this condition continue to worsen?
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.
