Treating cough in horses

What Is Coughing in Horses?

Coughing in horses is primarily a response to irritation of the respiratory tract. When foreign particles, dust, mold spores, or excess mucus accumulate in the airways, the horse’s body attempts to remove them through coughing. This reflex serves as a protective mechanism, helping to keep the upper and lower respiratory tract clear of harmful substances that could interfere with normal breathing.

Healthy and unobstructed equine airways are essential for survival because horses are flight animals that depend on efficient oxygen intake. Unlike humans, a horse can only breathe through its nose (obligate nasal breathing). During intense physical exertion, a horse can move up to 100,000 liters of air through its lungs.

However, if the airways become irritated and produce excessive mucus, the airway diameter decreases. As a result, the horse receives less oxygen, which can quickly lead to reduced performance, fatigue, and respiratory distress. Coughing helps the horse expel mucus and irritants from the respiratory tract before they settle deeper in the bronchi and bronchioles.

For this reason, coughing in horses should always be taken seriously. It is an important warning sign of respiratory disease, and the underlying cause should be identified and treated promptly.

Acute vs. Chronic Cough in Horses

Veterinarians differentiate between acute cough and chronic cough in horses.

• Acute respiratory problems are often caused by foreign bodies, viral infections, or bacterial pathogens. In these cases, veterinarians usually diagnose acute bronchitis in horses.
• If acute bronchitis is not treated properly, the inflammation can spread deeper into the lungs and affect the alveoli (lung air sacs), eventually developing into chronic bronchitis.

In advanced stages, chronic airway inflammation in horses may progress to conditions such as:

• Equine Asthma (modern veterinary term)
• RAO – Recurrent Airway Obstruction
• formerly referred to as COPD in horses
• or colloquially “heaves” (also known as heave line disease)

These conditions represent the most severe stage of chronic respiratory disease in horses and require long-term management, environmental adjustments, and veterinary treatment to maintain the horse’s respiratory health, performance, and overall well-being.

Horse Cough – One Symptom, Many Causes

Identifying what triggers a cough in horses can be challenging, as it is with many equine health issues. Horses may show the same symptom, but the underlying cause can differ from one horse to the next. In other words: there are many possible reasons behind a single symptom.

If a horse suddenly starts coughing, for example while eating, a foreign body such as feed particles or dust may have entered the trachea (windpipe). The horse then tries to expel it as quickly as possible through coughing and gagging. Once the irritant is cleared, the horse usually settles again.

If, however, the horse coughs repeatedly, more frequently, or in the same situations over and over, something may be wrong. To understand why, it helps to look briefly at how equine breathing works.

How a horse breathes

When inhaling, the horse draws air in through the nostrils and nasal passages. The larynx opens and clears the way into the lungs. Air flows into the two lungs, where the bronchi and tiny alveoli (air sacs) handle gas exchange, taking in oxygen and releasing carbon dioxide. During this process, the diaphragm and intercostal muscles expand so the ribcage creates enough space for the incoming air.

When exhaling, these muscles relax, the chest narrows, and pushes the air containing carbon dioxide back out through the nostrils. You can find further explanations in the article: Breathing in horses explained – recognizing and treating respiratory problems.

Movement plays an important role in keeping the lungs clear because breathing is directly linked to locomotion. That is why it is essential that horses, as natural athletes and movement animals, get daily free exercise. This supports overall respiratory health and helps the lungs’ natural clearance mechanisms.

A resting horse typically takes 8 to 16 breaths per minute. Under heavy exertion, this can rise to up to 150 breaths per minute and around 1,500 liters of air per minute, which is remarkable. How quickly the breathing returns to normal after work depends on the horse’s fitness level.

If a horse takes around 20 breaths per minute at rest, this can already be concerning and may indicate a problem.

Why horses cough

Viruses and bacteria can trigger the immune system to produce increased mucus in the airways to trap pathogens. Coughing is then a necessary reflex to move that mucus out of the respiratory tract.

In general, causes of equine cough can be divided into infectious and non-infectious factors:

Infectious causes

• Viral infections (equine influenza, equine herpesvirus)
• Bacterial infections
• Parasites (lungworms)

Non-infectious and other causes

• Mechanical issues, for example laryngeal hemiplegia (“roaring”)
• Heart problems, especially left-sided heart failure
• Tumors and abscesses
• Poor air quality (ammonia, insufficient ventilation, high dust load, mold spores)
• High humidity leading to mold growth
• Allergic reactions to pollen, hay dust, or straw dust
• Too little movement resulting in poor air exchange in the lungs
• Untrained or weakened immune system: inadequate detoxification, overburdened liver and kidneys, and an imbalanced gut microbiome
• Genetic predisposition
• Restricted or “blocked” diaphragm
• Pulmonary edema (fluid accumulation in the lungs), which can ultimately lead to suffocation in severe cases

With horse coughing, it is possible that several triggers overlap. Alongside viruses and bacteria, suboptimal stable management and housing conditions are frequent contributors. Sensitive horses with a weakened immune system are particularly prone to bronchitis or allergic coughing. Horses affected by sweet itch (insect bite hypersensitivity) are often mentioned in this context.

Symptoms and disease progression of coughing in horses

Symptoms and disease courses differ between an acute and a chronic form.

Typical signs of acute cough

• Swollen lymph nodes around the head and throatlatch area
• Labored breathing
• Fever from 39°C (102.2°F) and above
• Lethargy, dullness
• Reduced appetite
• Increased nasal discharge, often mucoid, cloudy, yellow to green
• Wet, mucus-producing cough (productive cough), which may become dry after a few days

If a horse has acute bronchitis, additional symptoms such as fever, fatigue, and loss of appetite are common. The horse is dealing with an infection where coughing is a key sign.

The infection causes swelling of the airways and increased mucus production. This narrows the airways and makes breathing more difficult overall. If the swelling is not reduced through veterinary treatment (medication, inhalation therapy, etc.), mucus can accumulate in the bronchi. This becomes a breeding ground for bacteria and may lead to a secondary bacterial infection, further weakening the horse’s immune system.

If acute coughing does not resolve after one to two weeks, or if mucus production persists for more than two weeks, the condition may become “dragged on” and develop into chronic bronchitis, which usually presents differently:

Typical signs of chronic cough

• Dry cough
• Increased respiratory rate, even at rest
• Shortness of breath
• Reduced performance
• A visible “heave line” (in German: Dampfrinne)

Symptoms such as fever, loss of appetite, or heavy nasal discharge—common in acute cough—often disappear in the chronic form. Instead, breathing becomes increasingly difficult, even without exercise.

Chronic bronchitis in horses is also referred to as heaves, equine asthma, COB, IAD, or RAO. The lungs’ natural self-cleaning function is severely impaired, which can worsen the horse’s overall health.

A veterinarian should not only be called when the condition becomes severe, but as early as the third day of persistent coughing.

Equine asthma and heaves in horses

Heaves (advanced equine asthma) is considered the end stage of chronic bronchitis. The airways are so narrowed and restricted that the horse can no longer exhale passively. It must actively engage the rib and abdominal muscles to move air, which can be seen as a tightened abdominal wall and the characteristic heave line.

Heaves is often associated with weight loss and pulmonary emphysema. This means the alveoli can rupture and lung tissue becomes damaged, potentially leading to partial loss of functional lung tissue.

If a horse has reached this stage of respiratory disease, it is no longer curable. At that point, only dust-free management and bronchodilating medication prescribed by a veterinarian can help relieve the symptoms. However, the horse will continue to struggle with recurring flare-ups, separated by symptom-free intervals.

What’s alarming is that around 10% of horses suffer from heaves and respiratory distress. Yet heaves is usually preceded by a long disease process—one that can often be prevented with the right treatment. That’s why you should involve your veterinarian early, as soon as your horse shows the first coughs. The rule here is simple: the sooner, the better.

You can find more in-depth information on equine asthma in this article: Equine Asthma—When Your Horse Runs Out of Breath: Causes, Diagnosis, and Treatment

Diagnosis by the Veterinarian

If a horse coughs for three days in a row, a veterinarian should examine it. The vet will usually begin with a thorough anamnesis (history) on-site at the stable. They will take the horse’s temperature, auscultate the lungs for abnormal respiratory sounds and coughing noises, and assess any nasal discharge.

However, lung auscultation is not always conclusive—especially in some breeds where listening to the lungs can be more difficult. In such cases, the veterinarian may perform a blood gas analysis, which measures the oxygen saturation and gas exchange in the blood and provides valuable information about lung function.

If further diagnostics are needed, a lung X-ray and/or a bronchoscopy may be performed. During bronchoscopy, a camera is guided into the airways and a mucus sample is collected. This sample is analyzed in a laboratory for bacteria, viruses, and fungi to help select the most effective treatment.

Treatment for Horse Cough

There are several treatment options for acute equine cough, most of them medication-based. These are prescribed by the veterinarian and should be started promptly to prevent mucus from settling in the bronchi. Possible treatments include:

• Mucolytics (expectorants): Especially Sputolysin. These liquefy mucus so it can be coughed up more easily and help the horse clear pathogens from the respiratory tract.
• Antispasmodics and bronchodilators: Bronchospasmolytics relax the respiratory muscles, increasing airway volume and improving lung performance. Bronchodilators are used particularly for allergic coughing.
• Anti-inflammatories: Most commonly corticosteroids, which reduce inflammation and swelling of the mucous membranes. This increases airway diameter, allowing the horse to breathe more freely and cough up mucus more effectively.
• Bronchoalveolar lavage (lung lavage): In severe cases, the veterinarian may need to flush the lungs if the lungs can no longer self-clean effectively. This procedure must be carried out in a veterinary clinic, as the horse requires monitoring afterwards.
• Antibiotics: Used only in cases of a secondary bacterial infection, to stop bacterial growth and spread and to eliminate bacteria that have colonized the mucus.
• Inhalation therapy: Supportive inhalation with saline solution or veterinarian-prescribed medication can provide relief by humidifying the airways and thinning mucus. Vets often recommend inhalation two to three times daily. Special equine inhalers/nebulizers atomize the solution into fine particles so it can reach deep into the respiratory tract.

Important: All equipment must be thoroughly cleaned with hot water after each use and then completely dried before the next session. Otherwise, bacteria can grow inside the inhaler and be inhaled by the horse.

In addition to medication, light exercise is important during treatment. Adapt the workload to your horse’s current condition. Gentle movement stimulates metabolism and breathing and helps loosen mucus so it can be coughed up more easily.

Home Remedies for Horse Cough: Herbal Teas and Respiratory Herbs

Respiratory teas and herbs can be given alongside therapy or as a preventative measure—especially for upper airway issues. Herbs can be a useful addition because they may have anti-inflammatory, mucosa-soothing, decongestant, and antispasmodic effects.

If you want to give herbs during an acute cough, avoid pre-made tea blends. Instead, consider mixing your own herbs to better control ingredients and quality. Pay close attention to purity to ensure contaminants do not interfere with recovery. It can also be helpful to change suppliers occasionally to reduce the risk of long-term exposure to unwanted residues.

You can feed respiratory herbs either as a lukewarm infusion or mix them dry into the feed. Common cough-support herbs for horses include:

• Anise
• Caraway
• Fennel
• Chamomile
• Eucalyptus
• Peppermint
• Sage
• Thyme
• Ribwort plantain
• Fenugreek
• Iceland moss
• Black cumin

As with people, a homemade cough syrup can sometimes help soothe irritated mucous membranes in horses. Chop onions, mix them with honey, and let the mixture rest overnight. The syrup that forms can have a calming effect on the airways.

Preventing Coughing in Horses

The following measures don’t just help prevent coughing in horses—they should also be top priority when treating acute equine cough. In horses with chronic cough (e.g., equine asthma/heaves), management must be fully adapted to a low-dust environment with plenty of free movement.

By nature, the horse is an athletic, roaming animal that needs regular movement, daylight, and fresh air to keep both the body and respiratory tract healthy. Long-term prevention is only realistic when these basic needs are consistently met.

Forage and Feed Quality

It sounds obvious, yet it remains one of the most common triggers of equine respiratory problems: feed quality. To help prevent coughing, roughage (hay/haylage) should be free from mold, fungal contamination, and (dried) toxic plants. Dirt and contamination that increase dust load should be avoided at all costs.

To keep airborne dust as low as possible, it’s best to distribute hay when horses are not in the stable. Horses with existing respiratory sensitivity may benefit from dampened/soaked hay.

Minimizing Dust Exposure

Fine dust particles are often trapped in the horse’s upper airways, but if dust levels are too high, particles can reach the lower respiratory tract, irritate it, and trigger increased mucus production.

To reduce this risk, keep the stable environment as dust-free as possible:

• Muck out, sweep, and bed down when horses are not inside
• After stable work, horses should only return after at least two hours, once the dust has settled

Wood shavings and other highly absorbent, chopped bedding materials can be a practical alternative to straw to help reduce dust.

Chronically affected horses often receive soaked hay (at least 30 minutes) or steamed hay (at least 10 minutes) to reduce dust in the forage. One drawback of soaking or steaming is that nutrients—especially minerals—can be reduced. Prioritize a high-quality mineral supplement to support immune function. Alternatively, soaked hay cubes (hay pellets/hay cobs) can be fed.

Horses should also avoid work on dusty footing (indoor arenas or outdoor riding arenas). If possible, water the surface before riding or training.

➡️ Videotipp: Healthy Lungs, Happy Horse: A Clean Stable and Supportive Herbs

Fresh Air and Ventilation

Respiratory disease in horses is especially common in closed stable systems where proper air exchange is neglected. Dust, high humidity, and ammonia fumes irritate the horse’s mucous membranes. For that reason, stable aisles in particular need effective ventilation without drafts.

The stable should be mucked out daily to reduce ammonia formation. Horses should not remain inside during mucking out and bedding down—ideally, they should only return to the stable after at least two hours, once airborne dust has settled.

For horses with lung disease, switching from a conventional stable to an open barn system (outdoor/open housing) should be considered.

Stable Temperature

Stable temperature should generally match the outside temperature. Large temperature differences between indoors and outdoors can weaken the immune system and also promote the growth of mold and fungal spores in the environment.

Free, Relaxed Movement

As a natural movement animal, the horse needs plenty of free exercise to stimulate breathing and support the lungs’ self-cleaning mechanisms. Ideally, the horse can move freely for several hours a day in turnout and/or an open barn system.

In addition, you can include gentle work or calm walks. Avoid stressful peak exertion, which can overload the lungs. In those moments, breathing becomes too rapid and shallow, and insufficient air reaches the deeper airways. Instead, exercise your horse lightly and appropriately, based on its health status and fitness level.

Strengthening the Immune System

The best protection against infections and coughing is a strong immune system. Especially during the cold, wet season, it is important to pay attention to your horse’s vitamin C supply. Rosehips are a well-known natural source and can be fed fresh, dried, or powdered. The herbs mentioned earlier can also support immune resilience and help make the horse less susceptible to respiratory infections.

A healthy immune system in horses also requires healthy intestinal flora, as this is where many immune cells are formed. When the seasons change, many horses experience watery stools and diarrhea due to a change in feed. Watery stools interfere with the absorption of minerals and upset the balance of the intestinal flora. You can find more information on causes, treatments, and differences in our article: Free fecal water and diarrhea in horses.
If the intestinal flora is out of balance, intestinal rehabilitation with probiotics may be beneficial. Healthy intestinal flora provides good protection against coughing.

Detoxification

It’s not uncommon to hear the term “liver cough” when a horse’s cough is associated with impaired liver function. The liver and kidneys are the body’s primary detoxification organs and therefore play an important role in the prevention of equine coughing.

If the horse’s immune system can no longer cope with toxins and irritants, the liver and kidneys step in to metabolize and eliminate harmful substances circulating in the body. You can support these organs by feeding diuretic herbs such as birch or metabolism-supporting herbs such as hawthorn.

Vaccinations

A common cause of acute coughing in horses is a viral infection. In addition to supporting the immune system, you can protect your horse with regular equine influenza vaccinations. While vaccination does not completely rule out an influenza infection, it can significantly reduce the risk and severity.

For more information on preventing equine herpes infections, see: Equine Herpesvirus—Causes, Symptoms, Treatment, and Prevention in Horses.

FAQ – Frequently Asked Questions About Horse Coughing

How long does a horse cough last?

An acute cough in horses should improve significantly or resolve within two weeks with appropriate treatment. If the cough—and therefore mucus production—persists for longer than two weeks, bacteria can settle in the airways and multiply. This can lead to a secondary bacterial infection, which may further worsen the horse’s overall health. If a horse coughs regularly for four weeks, it is often already considered chronic bronchitis (often associated with equine asthma/heaves).

Is a horse cough contagious to other horses?

Whether horse coughing is contagious depends on the underlying cause. Very often, an equine cough is triggered by a viral infection. Similar to humans, viruses and bacteria can spread from horse to horse. Whether another horse becomes infected depends on its immune status and the level of infection pressure (how many pathogens are circulating in the environment). During high-risk seasons, supporting your horse’s immune system—e.g., through balanced nutrition and targeted vitamin and mineral intake—can help reduce the risk.

If the cough is caused by allergies, cardiac insufficiency, or other non-infectious conditions, it is not contagious.

When should you call the veterinarian for a coughing horse?

In general, you should take a cough in horses seriously—but it isn’t always an immediate emergency. For example, a horse may cough briefly after choking while eating.

However, if the horse gags and coughs and feed material comes out of the nostrils, this can indicate choke (esophageal obstruction) and a veterinarian should be called immediately.

If your horse has been coughing for more than 3 days, especially if additional signs appear (such as fever, lethargy, reduced appetite, or labored breathing), you should contact your veterinarian urgently. Early intervention helps treat not only the cough, but also the underlying cause. When in doubt: call sooner rather than later.

How much should a coughing horse be exercised?

A horse’s respiratory system is closely linked to movement. Light exercise can support recovery in both acute and chronic cough cases because it promotes circulation, metabolism, and can help open the bronchi. This can make it easier for the horse to loosen and cough up stuck mucus.

The key is that exercise must be adjusted to the horse’s condition—avoid intense work or anything that causes stress or heavy breathing. The best approach is to discuss the right amount of movement with your treating veterinarian.