Equine asthma treatment study underway

With dust being the instigator, Laurent Couëtil, DVM, PhD, and his team are looking at how to reduce it

Laurent Couëtil uses an equine nebulizer to administer treatment for asthma.

Having already invented a means of diagnosing equine asthma, a professor at Purdue’s College of Veterinary Medicine is focusing his attention on treating horses with the condition.

Laurent Couëtil, DVM, PhD, professor of large animal internal medicine, director of Purdue University’s Equine Sports Medicine Center, has spent majority of his career treating and researching equine asthma.

“Milder equine asthma has been difficult to detect because horses don’t necessarily show many signs besides the fact they’re not performing well,” says Dr. Couëtil. “Some of them cough once in a while, but it isn’t crippling them. Now that we have the tools to look for it, we realize it’s very common.”

“In humans, the most common test performed to test for asthma is forced exhalation. The nurse trains you to take in the deepest breath possible and blow out as hard as you can. This is easy for people because we can follow instructions, but you can’t tell a horse to do that, so I worked with Purdue engineers to develop a pulmonary function test for horses.”

Corticosteroids are typically used to treat equine asthma; however, they come with a risk of drug violations in racehorses, suppress the horse’s immune system, and may result in life threatening infection.

Couëtil’s research shows the causes of equine asthma are generally environmental with the biggest risk being a dusty environment.

In a recent study, Couëtil worked with Purdue researchers to equip horses at a racetrack with sensors near their noses to measure how much dust they were inhaling. The findings showed most of the dust they inhaled came from hay.

“We know dust is the problem, but now we’re trying to figure out how to reduce it. In our next study, we’re testing different types of hay to see if we can reduce the amount of dust horses are coming into contact with while they’re eating,” Couëtil says.

In the study, some horses will be fed steamed hay, incubating in a sauna-like case for an hour killing much of the mold and dust, and other horses will be fed baled silage or haylage, a hay baled at a higher moisture content than dry hay and stored in a tightly sealed plastic wrap. When fed with a lower-dust feed option, Omega-3 fatty acid supplements were shown to enhance and hasten recovery.

“The horses that were fed the supplement improved much quicker and to a much greater extent. Many of them stopping coughing within a couple weeks,” Couëtil says. “The next step for us is trying to understand the mechanism that makes that happen.”

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