Do Hay Nets Make Equine Asthma Worse?

By Dr Duncan Houston

Hay nets are useful. They slow horses down, reduce wastage, and can help keep horses occupied in the stable.

But for a horse with asthma, coughing, poor performance, or breathing difficulty, the way hay is fed can make a huge difference.

The problem is not just “dusty hay.” Even hay that looks clean can release tiny respirable particles, mould fragments, endotoxins, and other irritants that sit right in the horse’s breathing zone while they eat. In horses with equine asthma, that can be enough to trigger coughing, airway inflammation, mucus, and reduced performance. (Merck Veterinary Manual)

Quick Answer

Yes, hay nets can make equine asthma worse in some horses, especially when dry hay is fed from a net inside a stall. Research and veterinary reports show that horses eating from stall hay nets can have much higher dust exposure than horses eating hay from the ground or a lower position. (DVM360)

For horses with asthma, the safest approach is usually to reduce dust exposure as aggressively as possible. That means avoiding dry hay in high nets, improving ventilation, using low-dust bedding, and considering soaked hay, steamed hay, haylage, hay cubes, pellets, or pasture where appropriate. (Merck Veterinary Manual)

What Is Equine Asthma?

Equine asthma is a chronic inflammatory disease of the lower airways. It is an umbrella term that includes mild to moderate asthma, previously called inflammatory airway disease, and severe asthma, previously called recurrent airway obstruction or heaves. Summer pasture-associated asthma is another form where outdoor allergens are a major trigger. (MSD Veterinary Manual)

In mild to moderate cases, the signs can be subtle. A horse may cough occasionally, tire earlier than expected, take longer to recover after work, or simply feel “not quite right” under saddle. Increased breathing effort at rest is not typical in mild to moderate asthma. (ScienceDirect)

In severe cases, horses may cough frequently, produce more airway mucus, flare their nostrils, breathe with obvious abdominal effort, or show a visible “heave line.” These horses are not just a bit dusty or unfit. Their lungs are inflamed and struggling. (MSD Veterinary Manual)

Why Hay Is Such a Big Trigger

Hay is one of the most important dust sources for stabled horses. The frustrating part is that hay does not need to look mouldy or dusty to cause problems. Even good-quality hay can contain organic dust that irritates sensitive airways. (Merck Veterinary Manual)

The most important dust is often the dust you cannot easily see. Fine respirable particles can travel deep into the lungs and trigger inflammation. This is why a stable can look clean but still be a poor environment for an asthmatic horse. (AAEP)

The horse’s “breathing zone” matters most. Dust sitting in the roof space is less important than dust directly around the nostrils while the horse is eating. When the horse’s nose is pushed into hay for long periods, exposure increases. (AAEP)

Why Hay Nets Can Be a Problem

Hay nets are not automatically bad for every horse.

For many healthy horses, they can be practical. They slow feeding, reduce waste, and help mimic longer foraging time. The issue is that asthma changes the rules.

When a horse eats from a hay net, especially a net inside the stall, the nose often stays close to the hay for long periods. That means the horse is inhaling directly from the dustiest part of the feeding setup.

Research discussed by equine respiratory specialists found a fourfold higher dust exposure in horses eating from hay nets inside the stall compared with horses eating from hay on the stall floor. (DVM360)

Another veterinary review reported that stall hay nets can increase dust exposure by three to four times compared with ground feeding. (The Horse)

That does not mean every hay net must be thrown into the bin. But if a horse has asthma, chronic cough, recurrent mucus, or poor performance linked to airway inflammation, a dry hay net in a stall should be treated as a genuine risk factor.

Is Feeding Hay on the Ground Better?

For many asthmatic horses, feeding from the ground or a very low feeder is better than feeding from a high net or rack.

A lower head position more closely matches natural grazing. It may also help airway drainage and reduce the amount of dust falling directly into the nostrils and eyes. The key is that the feeding area must still be clean. Feeding hay directly onto dusty bedding or a dirty stall floor is not ideal.

A good compromise is a clean rubber mat, a low feeder, or a ground-level feeding system that keeps the horse’s head low without forcing the nose deep into dry forage.

Risk Framework: How Worried Should You Be?

Low Risk

This is more likely if your horse:

• Has no cough

• Breathes normally at rest

• Performs normally

• Lives mostly outdoors

• Eats low-dust forage

• Has good ventilation and low-dust bedding

For these horses, hay nets may be acceptable, but still watch for coughing, nasal discharge, or reduced performance.

Moderate Risk

This is more concerning if your horse:

• Coughs during feeding or exercise

• Has mild nasal discharge

• Takes longer to recover after work

• Is stabled for long periods

• Eats dry hay from a net

• Has signs that come and go with stable management

This is the stage where changing the feeding system can make a big difference. Do not wait for obvious breathing difficulty before taking action.

High Risk

This is high risk if your horse:

• Coughs frequently

• Has repeated asthma flare-ups

• Has visible mucus on endoscopy

• Shows reduced performance despite fitness

• Has increased respiratory effort after exercise

• Gets worse when stabled or fed dry hay

These horses should have a veterinary assessment and a proper environmental plan. Medication may help, but long-term improvement depends on reducing dust exposure. (Merck Veterinary Manual)

Critical

This is urgent if your horse:

• Has laboured breathing at rest

• Flares the nostrils while standing still

• Uses the abdomen heavily to breathe

• Has a visible heave line

• Seems distressed, weak, or reluctant to move

• Has fever, depression, or abnormal nasal discharge

• Cannot comfortably eat, walk, or settle

A horse with breathing difficulty at rest needs urgent veterinary attention. Do not just remove the hay net and “see how they go.”

What Else Can Look Like Equine Asthma?

Not every coughing horse has asthma.

This is where proper veterinary reasoning matters. A cough may be caused by airway inflammation from dust, but it can also be caused by infection, viral respiratory disease, bacterial disease, strangles, equine influenza, equine herpesvirus, exercise-induced pulmonary haemorrhage, guttural pouch disease, sinus disease, aspiration, parasites, or less commonly cardiac disease.

In practice, the pattern matters.

A horse that coughs mainly while eating hay or soon after stabling is very suspicious for environmental airway irritation. A horse with fever, thick nasal discharge, swollen lymph nodes, sudden illness, or multiple affected horses on the property needs a different investigation pathway.

Veterinarians may use history, physical examination, rebreathing examination, endoscopy, tracheal wash, bronchoalveolar lavage, and sometimes lung function testing to confirm lower airway inflammation and rule out other causes. Bronchoalveolar lavage is especially useful because it helps identify the type of inflammatory cells present in the lower airways. (Purdue Vet College)

When Is This an Emergency?

Treat it as urgent if your horse is struggling to breathe.

Red flags include:

• Increased breathing effort at rest

• Nostril flaring

• Strong abdominal effort with each breath

• A heave line

• Distress or anxiety

• Weakness or collapse

• Fever with respiratory signs

• Thick, smelly, bloody, or one-sided nasal discharge

• Sudden worsening over hours

• A horse that cannot eat or settle because of breathing effort

Mild coughing is not the same as respiratory distress. But breathing difficulty at rest is never something to leave until tomorrow.

What Should You Do Right Now?

1. Remove the Dry Hay Net

If your horse has asthma or coughs while eating, remove the dry hay net as the first practical step.

This is not about blaming one piece of equipment. It is about reducing the dust sitting directly around the nostrils.

2. Feed From a Low, Clean Position

Use a clean mat, low feeder, or ground-level system. The goal is to keep the head low without forcing the horse to inhale from inside a dusty pile of hay.

Avoid feeding directly on dusty bedding.

3. Change the Forage, Not Just the Feeder

Forage is often the main exposure source, so changing the feeder alone may not be enough.

Options include:

• Steamed hay

• Properly soaked hay

• Haylage, where appropriate

• Hay cubes

• Forage pellets

• Complete pelleted feeds

• Fresh pasture where suitable

Steamed hay with low-dust bedding has been shown to produce very low respirable dust levels in the horse’s breathing zone compared with dry hay and straw systems. (ScienceDirect)

4. Use Soaked Hay Properly

Soaked hay can help some horses with severe asthma, and a controlled trial found that soaked hay improved clinical scores, lung function, and mucus scores over a six-week period.

But the details matter.

In that study, hay was soaked for 45 minutes, and dried-out leftovers were discarded between meals. Leaving soaked hay sitting around as it dries can increase bacterial growth and may re-release particles as it dries.

Soaking hay badly is classic stable science: looks like you’ve helped, but the lungs may politely disagree.

5. Improve the Whole Stable Environment

Focus on the full breathing zone, not just the hay.

Helpful changes include:

• Maximise ventilation

• Use low-dust bedding

• Avoid straw for sensitive horses where possible

• Remove horses during mucking out

• Avoid sweeping or using blowers near horses

• Do not store hay above stalls

• Avoid round bales for asthmatic horses

• Keep horses outdoors as much as safely possible

Environmental management is considered the single most important part of controlling equine asthma. Medication can help clinical signs, but signs commonly return if the horse remains in an allergen-rich environment. (Merck Veterinary Manual)

6. Speak to Your Vet About Medication When Needed

Some horses need corticosteroids, bronchodilators, inhaled therapy, or nebulised medication to control inflammation and open the airways.

The mistake is thinking medication replaces dust control. It does not. Bronchodilators may help a horse breathe more easily short term, but if the airways are opened while the horse is still inhaling dust, the underlying problem has not been fixed. (AAEP)

Common Mistakes Owners Make

Keeping the Hay Net but Changing Everything Else

Changing bedding, adding supplements, and opening a window may help, but if the horse is still eating dry hay from a net with its nose buried in the dust source, the biggest trigger may still be sitting right in front of them.

Assuming Clean-Looking Hay Is Safe

Good hay can still release respirable dust. If the horse coughs while eating it, the horse is giving you useful clinical information.

Soaking Hay and Leaving It All Day

Soaked hay should not sit around for long periods. Feed it promptly and remove leftovers before they dry out or spoil.

Treating the Cough Without Fixing the Environment

Medication may improve signs, but long-term control usually fails if the horse stays in the same dusty setup.

Ignoring Mild Coughing

A cough during exercise or feeding is not just a cute stable noise. It can be an early sign of lower airway inflammation.

How To Prevent Flare-Ups

The best asthma plan is boring, consistent, and slightly annoying to maintain. Very glamorous. Very effective.

Focus on:

• Low-dust forage every day

• Ground-level or low feeding for sensitive horses

• Steamed hay or correctly soaked hay when needed

• Hay cubes, pellets, or haylage for horses that react badly to hay

• Low-dust bedding

• Good stable ventilation

• More turnout where safe and practical

• Keeping the horse away during sweeping, mucking out, and hay handling

• Monitoring cough, respiratory rate, recovery after exercise, and performance

If you change from hay to soaked hay, pellets, cubes, or haylage, keep the full diet balanced. Horses still need adequate fibre, calories, minerals, and safe feeding routines.

Will My Horse Be Okay?

Many horses with mild to moderate asthma do very well when the trigger is identified early and the environment is cleaned up properly.

Severe equine asthma can be managed, but it is usually a long-term condition. These horses often need strict dust control, careful monitoring, and medication during flare-ups.

The key point is this: do not judge the horse only by how dramatic the cough sounds. Some horses with airway inflammation show subtle signs, especially poor performance or slow recovery. Others only look obviously sick once the disease is more advanced.

If your horse’s cough improves after changing from a hay net to low-dust ground feeding, that is useful information. If the cough continues, worsens, or returns every time the horse is stabled, your vet needs to investigate further.

FAQs

Are hay nets bad for all horses?

No. Many horses tolerate hay nets well. The concern is highest in horses with asthma, coughing, airway mucus, poor performance, or sensitivity to dry hay. In those horses, a hay net can keep the nose too close to the dust source for too long.

Can a horse with asthma still eat hay?

Some can, but dry hay is often a major trigger. Asthmatic horses may do better with steamed hay, properly soaked hay, haylage, hay cubes, pellets, or pasture, depending on their individual condition and diet needs.

Is soaked hay better than dry hay for equine asthma?

Often, yes, if it is done properly. Soaked hay can reduce dust exposure and has been shown to improve clinical signs and lung function in horses with severe asthma under strict feeding conditions. It should be fed promptly and leftovers should be removed.

Should I feed hay on the ground?

For many asthmatic horses, feeding from a low position is preferable to a high hay net or rack. Use a clean surface or low feeder so the horse is not eating from dusty bedding or manure-contaminated ground.

How long does it take for a horse’s asthma to improve?

Some horses improve within days if medication is used, but environmental improvement often takes weeks. If your horse has laboured breathing, worsening cough, fever, or poor performance that does not improve, organise a veterinary assessment rather than waiting.

Final Thoughts

Hay nets are convenient, but convenience is not always lung-friendly.

For a healthy horse, a hay net may be useful. For an asthmatic horse, especially one eating dry hay in a stall, it can place the nose directly into the highest-risk dust zone for much of the day or night.

The real goal is not simply “no hay nets.” The goal is clean air around the nostrils, low-dust forage, good ventilation, and a feeding system that supports the horse’s lungs rather than constantly challenging them.

If your horse coughs, struggles with performance, or breathes harder when stabled, the feeding setup is one of the first places I would look.

If you are unsure whether your horse’s cough is mild irritation or a sign of equine asthma, ASK A VET™ can help you work through the signs, feeding setup, and next steps with clearer guidance.