Equine asthma encompasses all of the inflammatory-type diseases that horses can get in their lungs, according to Dr. Amy Polkes. She owns an equine internal medicine mobile consulting practice called Equine IMED. She primarily practices in Maryland and Virginia, but she also attends horses in Pennsylvania, New York, and Connecticut, in addition to working part-time for Antech Diagnostics, a part of Mars Petcare.

(Editor’s note: The content of this podcast is the expert’s approach to the topic. Please consult with your practitioner if you have questions.)

What Is Equine Asthma Syndrome?

Polkes is a member of the American College of Veterinary Internal Medicine specialists, which in 2016 published a statement about equine inflammatory airway disease. “Recurrent airway obstruction (heaves) and IAD (inflammatory airway disease) represent a spectrum of chronic inflammatory disease of the airways in horses resembling human asthma in many respects,” the group noted. They decided to use the term equine asthma syndrome.

“The inflammatory disease in horses was close enough to asthma in people that we were going to give it a blanket term of equine asthma,” Polkes said. “So, that may be the horse that is young that has just a little bit of inflammation to a much older horse that has more of the typical type disease that you see where that used to be called COPD (chronic obstructive pulmonary disease) or RAO (recurrent airway obstruction, often called heaves), where they’re having trouble breathing at rest.”

Effects of Inflammation in the Lower Airway

Polkes said different cell types can cause inflammation in the horse’s lower airway, making it hard for air to get out. “There might be mucous, but it’s basically an obstruction in the lower airway,” she explained.

“And the reason that they have this sort of cough that can happen—or they have exercise intolerance—is because they can’t get air in and out of their lungs very well. Again, just like a person with asthma,” she continued.

Most of these horses don’t have a fever. They also don’t have nasal discharge, and their bloodwork is normal, she noted.

Diagnosing Equine Asthma

Polkes said veterinarians will do a bronchoalveolar lavage (BAL) to see what types of cells or other debris is in an affected horse’s airway.

Asthma in horses is most often driven by the environment, Polkes said. Causes can be dust and mold in the barn or hay.

Hay stored above stalls often creates a dusty environment for the horses living in the barn below. Horses can also be exposed to dust when eating from round bales, as they often stick their noses deep into the bale.

Horses moved from one location or country to another might have airway reactions to the new environment.
“The most important thing is environment, because we can treat the inflammation and we can treat the clinical signs, but we don’t often cure asthma,” stated Polkes. “We manage it just like in a person. When they have asthma, they have asthma.”

How to Treat Equine Asthma

Management is the most important part of treating equine asthma, said Polkes. She mentioned medications and supplements that can help improve the clinical signs of equine asthma.

Some management tools might include not storing hay over stalls and having good airflow in the barn. Polkes said some horses do better living outside, but others react to allergens in the outdoor environment and do better inside.

She recommends against feeding horses with whole round bales. If that is the best available forage, then Polkes suggests covering it with a large bale hay net to keep horses from burrowing their noses deep into the bale.

Other ways to mitigate environmental allergens include watering arenas before riding. You also can steam, soak, or wet hay before feeding it.

While steroids—including inhaled steroids—are used to treat equine asthma, Polkes warns against using those in horses with insulin dysregulation. Those horses are more prone to laminitis when receiving steroids.

Testing for Allergies

Polkes doesn’t do elimination allergen testing (i.e., for timothy hay). However, she said you can do serum allergy testing to get a general idea of what a horse is allergic to, such as grasses, weeds, or trees.

Polkes said it is important to assess horses when they first show signs of asthma. “It’s something that we want to catch as early as we can because the more severe they get, the harder it is to get them back into control,” she said. “So, it’s really important to notice even some little signs that you might see. Maybe they’re just coughing a couple of times and you might not think anything of it, but if you haven’t spoken to your vet about it, I would definitely recommend that.”

Final Words

Horses with pituitary pars intermedia dysfunction (PPID, formerly known as Cushing’s disease) might have chronic sinus infections or more severe asthma.

Polkes said horse owners also need to recognize when the environment changes. For example, some states have gotten more rain and snow, and some have been really dry.

“All these changes can affect how grasses, molds, weeds—all these things—have an effect on them,” Polkes said. “So, sometimes horses may be affected that never were affected [with equine asthma] before.”

Sign up for My Senior Horse’s FREE newsletter to get the latest information about equids 15 years and older delivered straight to your inbox!   

  • Kimberly S. Brown and Jewell

    Kimberly S. Brown is an award-winning writer and publisher. She founded My Senior Horse for Equine Network and Linda Mars in her retirement, and now she is an editor of the brand. Brown previously had spent 10 years at Equine Network. Prior to that she worked for three years in equine nutrition after she retired from nearly 30 years working at The Blood-Horse. Brown spent the last 15 years of her time at that organization creating and developing the award-winning The Horse and TheHorse.com.

    View all posts