How Barn Air Quality Affects Your Horse’s Respiratory Health

Veterinarians are seeing an increase in respiratory issues like equine asthma, sometimes referred to as “heaves.”

Dust, mold, fungal spores and ammonia can all cause inflammation when inhaled by horses. This can lead to an increase in mucus production, allergic reactions and risk of infection.

Many horses spend the bulk of their day inside a barn and are only outdoors when being ridden or turned out for short periods. For these horses, air quality in the barn is of great importance.

“When we expose horses to dust and particulate matter, we increase the risk of respiratory issues. High ammonia levels in the barn also contribute to poor air quality and exacerbate these issues,” notes Carissa Wickens, PhD, PAS, Associate Professor in the Department of Animal Sciences and Extension Equine Specialist at the University of Florida.

Wickens points out that air quality should be considered anytime a horse is in a confined space. This includes not only the barn, but indoor arenas, trailers and vans. 

Is Your Horse Coughing?

Coughing when starting to exercise can be a sign of a respiratory problem. If your horse coughs regularly or has recently started coughing, this should not be ignored. Consider the following:

  • Is coughing frequent or infrequent?
  • Is it only during exercise or does he cough while standing in the stall?
  • Does he cough while eating?
  • Does it sound deep or shallow?
  • Is there any nasal discharge?
  • Is his respiratory rate normal or elevated?

“It’s not uncommon for horses to cough at certain times of the year when there are more allergens, pollen and mold, but you need to pay attention, observe and know what’s normal for your horse. Know his normal vital signs,” says Wickens.

If changes occur, such as increased respiratory rate, coughing, and/or nasal discharge, this warrants a visit from the veterinarian.

“Consult with your vet and get symptoms addressed early,” says Wickens. “The sooner you address and treat any respiratory issues, the better.”

Evaluate Bedding

The type of bedding used can definitely contribute to dust and particulate levels in the barn.

Straw quality varies considerably. Even the cleanest straw contains spores that can cause respiratory irritation when inhaled by the horse.

“People may think straw is cleaner, but that’s not always the case. There’s more ammonia with straw and less with shavings, but both have the potential for dust and particulates,” says Wickens.

“The happy medium is a bedding that is low in dust and low in particulate matter, but at the same time has good absorption, to help reduce moisture and ammonia,” she notes. “This becomes a bit of a conundrum because some of our most absorbent beddings are wood products.”

When using shavings, Wickens recommends bigger — not fine — flakes, and avoiding sawdust. The smaller the flake, the faster it breaks down and the more dust you’ll have.

She says studies have shown that paper and cardboard bedding are less dust producing but may not be as absorbent as shavings.

“Peat bedding has very low dust and particulate matter, but it’s not common or practical in our industry in North America,” says Wickens, adding that peat is often used in the UK.

Stall Flooring

Horse owners may not be aware that the type of flooring in their stalls and barn also contribute to dust and particulate matter in the air.

For example, clay flooring, which is common in many barns, eventually breaks down because of the weight of the horse. This is often seen as a fine layer of clay dust on stall walls and horizontal surfaces like window ledges, etc.

Rubber mats over the top of clay floors will help, but crushed rock will hold up better and offer more drainage than clay.

“The worst thing is dirt floors without mats. At least add rubber mats over dirt and replace rubber stall mats when they become worn,” says Wickens.

“If you are starting from scratch, consider drainage under the stalls so ammonia can’t get trapped under or in the flooring,” she advises. “If you have concrete floors and interlocking rubber stall mats that offer a tight junction between seams, this prevents urine from being trapped underneath.”

Seamless rubber flooring systems are one of the best stall flooring choices but are also one of the most expensive options.

What’s That Smell?

If you can smell ammonia in the barn, this is never good.

“Ammonia is a respiratory irritant to stalled horses. When a horse is spending enough time in the stall that they are lying down and sleeping, their face is right at floor level which is where ammonia concentration is highest,” says Wickens, who advises using a stall amendment that mitigates ammonia in the air.

“A lot of people clean the stall, spread lime, put down bedding and then put the horse right back in the stall, but this initially puts more ammonia in the air. If you use lime, let the stall sit and put the horse in later in the day,” she advises, adding that stall amendments with active ingredients that trap ammonia or prevent ammonia from becoming volatile are preferred over lime.

Interestingly, Wickens points out that the horse’s diet influences ammonia level. Research has shown that horses fed higher levels of protein have more nitrogen levels in their urine. It is nitrogen that breaks down into ammonia and causes the telltale smell.

One simple way to decrease ammonia levels in the barn is to not feed excessive protein. For example, idle horses and “easy keepers” usually don’t require high protein diets.

Cleaning Stalls

If you’ve been cleaning stalls while your horse is inside the stall or just moving him to a neighboring stall, it’s time to change that practice.

Studies show that cleaning stalls greatly raises dust and particulate levels in the barn because of tossing and sifting bedding to separate out manure and soiled areas. Those levels are even higher when blowers are used to clean barn aisles.

“When you’re cleaning your stall and see little floating motes in the ray of sunlight coming in, this is dust and particulate matter,” says Wickens. “Small management changes can go a long way in reducing your horse’s exposure to dust and particulate matter and ammonia.”

The best practice is to clean when horses are out of the barn so they’re not breathing in the dust and particulate matter stirred up by cleaning. Then let everything completely settle before putting horses back in their stalls.

Ventilation Is Important

Take a close look at your horse’s barn. If it has a low-pitched roof and a full or partial overhead loft, this presents a ventilation problem. If the loft is used to store hay or straw, this can be a major contributing factor to dust and particulates in the air. Overhead lofts are also a fire hazard — even if you don’t use them to store hay.

For effective natural ventilation, there should be a fully vaulted ceiling over the stalls ¬— no loft.

Proper ventilation takes place from bottom to top, not only from side to side. If the barn is well-designed, fresh air is drawn in at low levels and rising warm air escapes out of ventilation devices, such as clerestories, ridge vents, dormers with vents and cupolas.

“Good ventilation is about more than just putting in fans. You need inlets and outlets for regular air exchange,” says Wickens.

While you may not be able to totally redesign your existing barn, you can make changes to bring in more fresh air.

If there is a loft, keep it empty. Store hay and straw in structures that do not house horses.

Exterior openings, including windows and vented doors, will allow for more air movement. Replace solid stall fronts and doors with open-steel mesh stall fronts and stall doors to provide more air exchange.

Even in cold weather, exterior doors can be open more than shut.

“When it’s warm in a barn, this might be more comfortable for the people, but when it’s cold, that means more air movement, which is better for the horses,” notes Wickens, adding that the goal is to have good air movement, but to avoid drafts on horses in stalls.

Indoor Exercise

Many owners ride in an indoor arena or use it for turn-out so their horses can get out of the stall and have some exercise.

Research has shown that when horses are exercised indoors there can be very high particulate levels if the surface is not dampened.

“Regular maintenance of the surface, regardless of how it’s used for exercise or turn out, needs to be done to keep dust levels down. Depending on the surface, this may mean wetting it down,” says Wickens. “Some of the newer synthetic surfaces don’t need to be dampened, or require a different conditioning agent or method. It depends on the surface and how it should be managed.”


Although short-duration trailering may not pose much of a problem with respiratory issues, extended travel definitely can.

One big concern is that when a horse is tied in the trailer for hours, he doesn’t get a chance to fully lower his head and clear his airways and nasal passages.

Wickens points out that it’s much healthier if the horse can be loose when traveling so he can lower his head. If this is not possible, at the very least you should walk the horse around once at your destination and give him the opportunity to stretch his neck and drop his head.

Don’t use sawdust to bed trailers for long trips! It may soak up urine, but it’s high in dust and particulate matter.

Air Quality Index

You’ve likely heard “Air Quality Index” mentioned on weather reports, but haven’t realized how it can apply to horses.

The National Collegiate Athletic Association (NCAA) already uses the AQI when making recommendations about athletic activities. This includes rescheduling athletic activity or moving it indoors when the AQI is 200 or above.

Wickens says these parameters may also be applicable to equine athletes and advises horse owners to monitor AQI.

“Days with poor air quality may not be good days for strenuous exercise,” she says. “If your horse is suffering from respiratory issues, this is part of the management and something to consider.”

Courtesy of Stable Talk by Farnam