Steaming Hay
You Steamed the Hay. Is Your Horse Still Breathing Dust?
Steamed hay is often treated as the answer to a dusty stable. Buy the steamer, follow the directions, and the horse’s breathing problem is handled—or so the thinking goes.
The reality is more complicated.
Steaming hay can reduce respirable particles and improve its hygienic quality. That can make it a useful part of an air-quality plan. But recent research involving horses with severe equine asthma offers an important reminder: reducing dust in one part of the horse’s environment is not the same as controlling the horse’s total exposure.
For a carriage-driving horse, that distinction matters. The respiratory system is part of the performance system. A horse cannot condition, recover, or comfortably sustain work if the airways are being repeatedly irritated.
What the steamed-hay study found
Researchers followed nine adult horses with severe equine asthma that were in remission. Each horse received dry hay for four weeks and steamed hay for four weeks, with a washout period on pellets between the two phases. The team measured lung function, airway inflammation, and clinical signs.
After four weeks, both hay treatments were associated with a mild but measurable worsening in lung function and an increase in neutrophils—the inflammatory cells measured in fluid collected from the lower airways. The researchers did not find a meaningful difference between the dry-hay and steamed-hay periods. Clinical scores did not change significantly.
That last point deserves attention. The horses did not necessarily look dramatically worse, yet testing detected changes in lung function and airway inflammation. We cannot assume that a horse’s airways are entirely comfortable simply because there is no obvious coughing fit at the barn door.
This was a small study, and it should not be read as proof that steaming never helps. The researchers worked with only nine horses, the asthma exacerbations were milder than expected, and dust exposure at the horses’ breathing zone was not directly measured. The study also examined horses with a particular disease history under a particular management setup.
Its strongest message is narrower: steamed hay alone did not prevent mild airway deterioration in this group.
The horse breathes an environment, not an ingredient
We tend to discuss hay, bedding, ventilation, and arena footing as separate management decisions. The lungs do not experience them separately. The horse receives one combined inhaled dose over the course of the day.
Think of it as a daily dust budget. Exposure may come from:
Forage and the way it is fed
Bedding disturbed by movement or mucking
Sweeping and blowing barn aisles
Poor air exchange in a closed stable
Dusty indoor-arena footing
Nearby horses eating or stirring up bedding
Transport in an enclosed trailer
A stable can look tidy and smell pleasant while still containing small airborne particles that are invisible to us.
A 2026 case study at one equestrian facility found that a substantial portion of the measured dust was in the respirable range, particularly in the indoor arena. Because this was a facility-specific study, its measurements should not be applied to every barn. It does, however, reinforce the need to look beyond the hay net when assessing air quality.
Another study measured dust directly in the breathing zones of 50 horses during feeding. The amount of contact a horse made with the hay was strongly associated with exposure to fine particulate matter.
In plain language, a horse that buries its nose deeply into forage may inhale a different dose than a horse eating the same hay with less nose-to-hay contact.
This does not mean we should automatically raise every hay net or abandon natural feeding positions. Feeding height affects more than dust exposure, and prolonged high feeding has drawbacks of its own. It means we should observe the individual horse: How does this horse eat? Where does the dust go? What other exposures surround the meal?
Why this matters in carriage-driving training
Driving horses frequently work for sustained periods, sometimes on hills, in heat, on roads, or in deep footing. They may also spend time waiting in a trailer, standing at an event, or warming up in a busy indoor arena.
Respiratory demand increases with work, so air quality is not merely a stable-management topic. It is part of conditioning and recovery.
Possible warning signs include coughing, nasal discharge, increased breathing effort, slower-than-expected recovery, or a drop in willingness or performance. None of these signs diagnoses asthma, and poor performance has many possible causes. Persistent or recurring changes deserve veterinary evaluation rather than simply more conditioning.
For instructors, this is also a valuable client-education point. When a horse seems “unfit,” ask about the entire 24-hour environment before assuming the training program is inadequate. More work is not the right answer if breathing is the limiting factor.
A more complete air-quality plan
Steamed hay may still have a place, particularly when it is recommended as part of a veterinarian-directed plan. But it works best as one control among several.
Practical steps include:
Increase fresh-air exposure. Maximize appropriate turnout and maintain real air exchange in the stable. A closed, warm barn is not necessarily a healthy barn.
Choose forage by quality, not appearance alone. Store it carefully and reject visibly moldy forage. For a horse with diagnosed asthma, discuss suitable forage forms and preparation with your veterinarian.
Use steaming or soaking correctly. Each has management, hygiene, and nutritional considerations. Follow equipment directions and veterinary or nutrition advice rather than improvising.
Select low-dust bedding. The benefit of cleaner forage can be undermined by a dusty stall.
Move the horse before cleaning. Muck, sweep, or use blowers while horses are out. Allow suspended dust time to clear before bringing them back.
Manage the working surface. Water and maintain arena footing appropriately. If the indoor looks hazy, that is a training-environment problem—not merely a housekeeping issue.
Observe feeding behavior. Look at where the horse’s nose is, how vigorously the forage is shaken, and whether visible dust clouds form during eating.
Track respiratory response alongside fitness. Record coughs, respiratory effort, recovery time, and unusual performance changes. Patterns are more useful to a veterinarian than a vague report that the horse “just isn’t right.”
The bottom line
The practical takeaway is not “never steam hay.” It is “do not let steamed hay create false confidence.”
A steamer can reduce one source of exposure, but it cannot ventilate the stable, change dusty bedding, settle the arena, or prevent sweeping beside a horse that is eating.
For the driving horse, protecting the lungs is part of building fitness. The best question is not simply, “What did we do to the hay?”
It is: “What has this horse been breathing all day?”
This article is educational and is not a substitute for veterinary diagnosis or an individualized asthma-management plan.
Research discussed
Barton et al., “Steamed hay for the prevention of severe equine asthma exacerbations,” Equine Veterinary Journal. Read the study
Jaksic et al., “Minimising feeding behaviour interference: A hay-shaker device to assess dust exposure in horses,” Equine Veterinary Journal. View the PubMed record
“Air Quality Assessment and Potential Inhalation Exposure Across Equestrian Facilities: A Case Study,” Atmosphere. Read the study
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