Horse Respiratory Issues: Management of Asthma and Other Disorders

Though equine respiratory issues are on the rise, it can be challenging to make management changes that keep these horses healthy.

The breath of a horse with a respiratory disease such as asthma
Photo by Estelle R/Shutterstock

Ask anyone with asthma what it’s like to have an attack and words like “suffocating,” “drowning,” and “an elephant on my chest” are a common refrain. The Asthma and Allergy Foundation of America explains that asthma is a “long-term disease that causes inflammation and swelling of the airways,” meaning that the asthmatic truly cannot get enough air into their lungs. Asthma in humans has been on the rise in recent years, and it certainly seems that more horse owners are also battling the disease and other respiratory issues among their horses. Being able to identify asthma triggers is an important part of keeping people—and horses—healthy.

Once asthma triggers like dust, pollen and animal dander are identified, many human asthmatics make lifestyle changes to minimize their exposure, giving them the best chance to remain healthy. While it would seem intuitive that similar lifestyle changes would be warranted in horses, a recent study conducted by the University of Lisbon found that the majority of horse owners and managers were reluctant to implement any kind of adjustment to the horse’s routine.

Knowing that these changes are imperative to—quite literally—being able to breathe, why are some horse owners slow to adopt management changes?

Clinical Signs and Diagnosis

Lais Rosa Costa, MedVet, Ph.D., DACVIM, DABVP, director of operations for the Veterinary Emergency Response Team at the UC Davis School of Veterinary Medicine, is a boarded large animal internist whose clinical and research work has focused on respiratory diseases, especially severe equine asthma.

Though equine respiratory disease ranks second only to musculoskeletal disease in disorders that limit performance horses, signs of pulmonary disease often come on slowly, causing them to be unnoticed by owners and farm managers until clinical signs are severe.

According to Costa, signs a horse may be suffering from pulmonary disease include exercise intolerance and increased respiratory rate or increased respiratory effort. A horse suffering from asthma will often cough from increased mucus production. Any of the chronic or recurrent pulmonary diseases will cause a horse to work harder to breathe, leading to poor performance and weight loss, she notes.

A man leading a pinto out of an arena
Signs a horse may be suffering from pulmonary disease include exercise intolerance, increased respiratory rate or increased respiratory effort. Photo by Firefighter Montreal/Shutterstock

It’s imperative that the root cause of horse’s health issue be defined and differentiated from other conditions, such as cardiac diseases, Costa says. This will require getting a thorough history, along with a detailed clinical examination.

“The lungs have limited ways to deal with insults, so many of these conditions manifest similarly, but the trigger is specific for the condition,” she explains.

Additional respiratory diagnostics may be needed to narrow down the source of a horse’s problem, says Kate Christie, DVM, DACVIM, an associate veterinarian with Rood and Riddle Equine Hospital in Lexington, Ky., who has a special interest in respiratory disease.

“Diagnostics are aimed at determining whether the problem is in the upper or lower airway, as well as whether the problem is infectious or inflammatory in nature,” says Christie. “The answer to these questions helps us come up with a treatment and management plan for each individual horse.”

Additional diagnostics may include bloodwork, diagnostic imaging (ultrasound examination and chest radiographs), specific airway diagnostics like endoscopy, and—if equine asthma is suspected—bronchoalveolar lavage, she explains.


Once the trigger is identified, management changes to reduce or eliminate the issues causing breathing distress are imperative for the horse’s health. This can be tricky—especially in cases of inflammatory airway disease, according to Christie.

A horse jogging in a dusty arena, which can trigger respiratory diseases like equine asthma
Triggers, such as dust, are specific to the horse’s respiratory condition. Diagnostics should be used to determine the root cause of a breathing problem. Photo by Oleksandr Zastrozhnov/Shutterstock

Though the “gold standard” of care would be to remove all dust and allergens from a horse’s environment, it’s simply not possible to completely eradicate these, as horses are expected to be ridden in arenas, to eat forage, and often to sleep on some form of bedding.

“Although it’s really difficult, environmental management is the cornerstone of treating inflammatory conditions of the lower airway,” says Christie. “You could provide the horse with all the medication in the world, but if the environment isn’t improved, the horse won’t respond as well [to treatment]. Our recommendations for environmental management are all aimed at decreasing exposure to airborne allergens, including dusts and molds.”

Some of the modifications need not be as overwhelming as they initially appear.

Horse Respiratory Health Myth No. 1: All horses with allergy issues should have wet hay.

Reality: Wetting hay is not the cure-all solution it was once believed to be.

“[Wetting hay] actually increases the amount of mold and exacerbates conditions like equine asthma,” says Costa. “Washing the hay, or—better yet—steaming the hay are effective ways to decrease organic particulate matter.”

Management change: While not everyone will be able to afford a hay steamer or the time to go to the barn twice a day to make cleaning the hay a reality, there are other ways to make a forage change work, according to Costa. A complete pelleted diet, pelleted hay, and haylage are a few options to consider, but no diet change should be done without the input of a veterinarian or an equine nutritionist to be sure the horse receives adequate and appropriate fiber and nutrients.

Horse Respiratory Health Myth No. 2: Bedding doesn’t matter if the horse isn’t in the stall when it’s cleaned.

Reality: A horse stalled on any type of bedding that contains contaminants that trigger a pulmonary response is at risk, and not just when the stall is being cleaned. Simply walking around in the stall can stir up enough dust to cause breathing issues.

While no horse should be kept in the stall while it’s being cleaned, asthmatic horses must be removed before the stall is mucked, and should remain out of the barn for at least one hour after cleaning.

Management change: Straw is one of the dustiest (and moldiest) types of bedding that can be used, with rice hulls and sawdust not far behind. Good quality wood shavings are not as bad.

“Severely asthmatic horses have to be bedded on shredded cardboard bedding or rubber mats with no bedding at all,” says Costa.

An even better solution? Turn the horse out 24/7.

“Many horses resolve [their breathing issues] completely with 24-hour turnout alone,” says Christie. The only time this recommendation varies is when horses are diagnosed with summer pasture associated recurrent airway obstruction (SPARAO). This condition is more common in the southeastern United States and is characterized by difficulty breathing when pastured in the summer. Pollens and other seasonal allergens are suspected to be the cause, according to Christie.

A chestnut resting in a stall
If a horse can’t live on 24/7 turnout, straw is the dustiest bedding, while shredded cardboard is the least. Good-quality wood shavings fall somewhere in the middle. Photo by Lindsay Helms/Shutterstock

Similar to the barn-associated equine asthma, implementation of management changes is crucial for effective care of SPARAO, and without them, these horses do not respond to medical therapies, Costa says. This is a seasonal recurrent condition that can be controlled successfully with management changes and minimal medical therapies.

Horse Respiratory Health Myth No. 3: Stall location doesn’t matter.

Reality: Similar to a real estate expert, the owner of a stalled horse with breathing issues should be concerned with one thing: Location, location, location. While owners may think stalls located near doors are more uncomfortable for the horse in cold, blustery weather, the reality is the more airflow, the better.

Management change: Though horse and barn owners can get stuck in routines that are hard to change, this adjustment is one of the easier ones to implement. Moving a horse closer to a doorway, away from the indoor arena or even to a stall with a window can offer some immediate relief to the afflicted equine.

The breath of a horse with a respiratory disease such as asthma
Move a horse with asthma toward the end of the barn aisle by the open barn door and away from any indoor arenas. Photo by Virrage Images/Shutterstock

Equine asthma is a lifelong condition for which there is no cure. But be assured that even small changes can make a big impact for a horse that has a difficult time breathing.

“I often stress that [owners] can spend a lot of money on medical therapies, but these won’t make a difference if the environment is not controlled,” says Christie. “If people are able to adhere to environmental changes and keep flare-ups to a minimum, it’s less likely that the horse’s condition will progress to recurrent airway obstruction (RAO) or heaves—a much more serious and severe category of equine asthma.”

Costa also feels that management should be the No. 1 priority.

“Our job as veterinarians is to help owners and caretakers understand the importance, although sometimes challenging, of implementing management changes [that go hand-in-hand with treatment],” says Costa. “The management changes have to be realistic. Sometimes we have to be creative. The best [way to handle the situation] is to keep a positive outlook and do the best that is possible.”

While these changes may take some planning to implement, the horse’s quality of life can quite literally depend on it.

Smoke Inhalation

A wildfire behind a herd in the mountains
Photo by Tom Reichner/Shutterstock

Horses affected by barn fires and wildfires face a different set of issues that those with equine asthma and other airway diseases. Lais Rosa Costa, MedVet, Ph.D., DACVIM, DABVP, a veterinarian at the UC Davis School of Veterinary Medicine in California, has seen multiple horses affected by smoke inhalation from wildfires.

“Smoke inhalation affects both the upper airways and the lower respiratory tract,” Costa explains. “Much of the acute signs of smoke inhalation injury are associated with toxic compounds released upon combustion [plus] inhalation thermal injury. “

The immediate concern is treating the acute smoke inhalation injury, which entails managing acute respiratory distress, decreasing inflammation, and preventing secondary infection.

Kate Christie, DVM, DACVIM, an associate veterinarian with Rood and Riddle Equine Hospital in Lexington, Ky., notes that horses involved in fires can be severely affected by smoke and particulate inhalation—sometimes days after the initial insult to their lungs.

“A massive inflammatory response may be initiated [by smoke and particulate inhalation] that causes severe pulmonary disease,” she says. “This response can be delayed from the initial exposure and is a huge problem for horses that survive barn fires. Permanent damage from smoke inhalation is also possible, and these horses may have prolonged respiratory disease that is difficult to manage.”


This article about management of horse respiratory issues like asthma appeared in the September 2022 issue of Horse Illustrated magazine. Click here to subscribe!


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