Respiratory Problems in Horses: Coughing, Heaves, and Stable Dust

A horse that coughs, or seems to run out of breath faster than usual while being ridden, is sending a signal you shouldn't ignore — but shouldn't overreact to either. Coughing has many possible causes, ranging from a harmless irritation to a chronic respiratory condition. This overview helps you judge what you're seeing and when the vet needs to get involved.

What Coughing Can Mean

A single cough at the start of work, after which the horse breathes easily for the rest of the session, is usually harmless — comparable to clearing your throat. Persistent coughing, coughing at rest, or a horse that's audibly struggling to breathe is not.

The most common underlying causes, broadly, are:

• Irritation from dust or ammonia in the stable, often the start of a bigger problem.
• Viral or bacterial respiratory infections, usually accompanied by fever, nasal discharge, and lethargy.
• Allergic or inflammatory airway conditions, of which heaves is the best-known chronic form.
• Exercise-related complaints, where the horse only coughs or becomes short of breath during or right after work.

Which one it is, you can rarely say for certain from the outside. The combination of signs — fever or not, discharge or not, at rest or only during work — largely determines the direction, and that assessment belongs with the vet.

Heaves: The Chronic Form

Heaves — also known as RAO (recurrent airway obstruction) or, under the broader modern term, equine asthma — is what Dutch vets call dampigheid: a chronic, recurring airway inflammation. It isn't a contagious disease but a hypersensitivity reaction of the lower airways, usually to dust, mould spores, and allergens in hay and bedding.

Characteristic signs:

• Coughing that keeps coming back, often worse in the stable than in the field.
• Reduced stamina; the horse is out of breath sooner than it used to be.
• In more severe cases, visibly increased abdominal breathing effort, sometimes with a heave line along the flank (an exhalation groove).
• Sometimes a bit of clear nasal discharge.

Heaves usually can't be cured, but in many horses it can be kept well under control by adjusting the environment and, where needed, with medication from the vet. The sooner you remove the triggers, the better the outlook usually is.

When to Call the Vet

If in doubt, calling is always defensible. Get in touch in any of these cases:

• Fever (a resting temperature clearly above normal, which sits roughly around 37.5–38.5°C — measure it yourself if unsure and report the value).
• Labored breathing at rest, flared nostrils, or audibly heavy or wheezy breathing without the horse having just worked.
• Coloured or thick nasal discharge, especially from both nostrils.
• Coughing that persists for days or keeps coming back.
• Not wanting to eat, lethargy, or a rapidly declining condition.

Acute, severe respiratory distress where a horse is visibly struggling for air is an emergency — don't wait on that. The vet can use listening, possibly bloodwork, an endoscopy, or an airway lavage to determine where the coughing is coming from. Don't improvise medication yourself; dosage and drug choice belong with the treating vet.

Stable Dust: The Biggest Lever You Control

With almost all non-infectious respiratory complaints, the environment is the most important factor. A horse stands with its nose close to hay and bedding, exactly where the most dust and mould spores are released. The following adjustments reduce the dust load:

Sweeping, shaking out straw, and emptying a hay net briefly cause the highest dust concentration. Don't do that with the horse in the stable. In a horse with confirmed heaves, soaking or steaming hay is often the single most effective measure.

Coughing or Labored Breathing During Exercise

A horse that only coughs while being ridden, or gets out of breath faster than you're used to, deserves attention. Sometimes it's a harmless warm-up cough in the first few minutes; sometimes exercise is exactly the moment a dormant respiratory problem becomes visible, because breathing is under heavier load then.

Watch for a horse that:

• consistently doesn't want to go forward, or tires sooner than in comparable periods;
• keeps panting longer after work than makes sense for the effort delivered;
• coughs as soon as it picks up canter or works in a dusty indoor arena.

For competition riders, there's another factor: medication for respiratory complaints often falls under anti-doping rules. What you give your horse and what withdrawal period applies should be discussed with your vet and checked against the official source — see the clean-sport and anti-doping policy of the KNHS (the Dutch equestrian federation) and, for international starts, the FEI (the international equestrian federation). Never wing this on a hunch.

In Short

An occasional cough at the start of work is usually harmless; persistent coughing, labored breathing at rest, fever, or thick nasal discharge are not, and belong with the vet. Heaves is a chronic respiratory condition you can often manage well by making the environment low-dust. The biggest gains usually come from soaked or steamed hay, low-dust bedding, good ventilation, and more turnout. If you're unsure about the severity or about medication around a competition, run it by your vet — improvising here is worse than making a phone call.

See also: Veterinary Health Care: Vaccinations, Deworming, and Dental Care · Daily Horse Care: The Basic Routine · Recognizing Colic and Other Emergencies in Horses · Glossary