Why Is My Horse Coughing? Common Causes, Red Flags and What To Do

By Dr Duncan Houston

A horse may cough once after inhaling dust and never do it again. That is very different from a horse that coughs every time it trots, repeatedly while eating, after travelling, or while standing quietly in the stable.

The cough itself is only a clue. What matters most is when it happens, how often it occurs, whether the horse has a fever, and whether breathing, appetite or performance have changed.

Some causes are manageable environmental problems. Others, including choke, pneumonia, influenza, EHV and severe equine asthma, require prompt veterinary attention.

Quick Answer

An isolated cough in a bright horse with a normal temperature and normal breathing may simply reflect temporary airway irritation. Repeated coughing, coughing during exercise, coughing with nasal discharge, reduced performance or coughing that continues beyond 24 to 48 hours should be investigated.

A resting temperature of 101.5°F or 38.6°C or higher, particularly after travel or contact with other horses, should raise concern for infectious disease. Isolate the horse and contact your veterinarian. Laboured breathing, feed coming from the nostrils, collapse or significant bleeding from the nose is an emergency.

When Is a Coughing Horse an Emergency?

Call a veterinarian immediately if your horse has:

• Laboured breathing while standing at rest

• Marked nostril flaring

• Strong abdominal effort with every breath

• Blue, grey or very pale gums

• Rapid deterioration over minutes or hours

• Collapse, severe weakness or inability to stand

• Feed, water or saliva coming from the nostrils

• Repeated retching, neck stretching or distress while eating

• Heavy or unexplained bleeding from one or both nostrils

• Fever with neurological signs

• A high fever with depression, poor appetite or rapidly increasing breathing rate

• Severe signs after recent long-distance transport

• Foul-smelling discharge with respiratory distress

• Suspected aspiration after choke

Feed or water coming from the nostrils strongly suggests a swallowing problem or oesophageal obstruction, commonly called choke. Remove access to feed and water and contact a vet. Continuing to eat or drink can worsen aspiration into the lungs. (Merck Veterinary Manual)

Is It Normal for a Horse to Cough Occasionally?

One isolated cough can occur when a horse inhales dust, feed particles or another irritant. The airway uses coughing to remove material that should not be there.

Repeated coughing is different.

A horse that coughs during most rides, repeatedly when eating hay, every morning in the stable, or while resting may have active airway inflammation. Mild equine asthma can be subtle, and affected horses may breathe normally at rest while still experiencing cough, excess airway mucus and reduced performance. (Merck Veterinary Manual)

A warm-up cough should therefore not automatically be dismissed as the horse “clearing its lungs.” It may indeed be moving accumulated mucus, but the reason that mucus is present still deserves attention.

What Does the Timing of the Cough Tell You?

The timing does not provide a diagnosis on its own, but it can narrow the possibilities considerably.

When the horse coughs	More likely considerations
While eating dry hay	Dust irritation, equine asthma, swallowing dysfunction
With feed or saliva from the nostrils	Choke, dysphagia or pharyngeal dysfunction
On entering a dusty stable	Airway irritation or equine asthma
At the start of exercise	Airway mucus or inflammation, often mild equine asthma
Throughout exercise	Asthma, respiratory infection or lower airway disease
With abnormal noise during fast work	Dynamic upper airway obstruction
After strenuous exercise	EIPH may be considered, but coughing alone does not diagnose it
After transport	Viral infection, bacterial pneumonia or pleuropneumonia
During hot, humid pasture conditions	Summer pasture-associated severe equine asthma
At rest with visible breathing effort	Severe asthma, pneumonia or another serious respiratory disorder

The Most Common Causes of Coughing in Horses

1. Dust, Mould and Environmental Irritation

Horses inhale large quantities of air, particularly during exercise. Dust from hay, bedding, arenas and stable aisles can irritate sensitive airways.

Common triggers include:

• Dry or visibly dusty hay

• Mould spores

• Fine arena dust

• Straw or dusty bedding

• Poor stable ventilation

• Hay stored above stables

• Ammonia from urine

• Smoke

• Polluted air

• Sweeping or blowing stable aisles while horses remain inside

A brief exposure may produce an isolated cough. Repeated exposure can contribute to persistent lower airway inflammation and equine asthma.

The important point is that hay does not need to look mouldy to contain respirable dust and microscopic particles. Even apparently good hay can trigger signs in susceptible horses. Environmental allergen reduction is considered the foundation of equine asthma management. (Merck Veterinary Manual)

2. Mild to Moderate Equine Asthma

Mild to moderate equine asthma was previously called inflammatory airway disease.

It commonly affects young and athletic horses and may cause:

• Occasional or recurrent coughing

• Coughing during warm-up

• Excess mucus in the trachea

• Reduced stamina

• Longer recovery after exercise

• Poor performance

• Noisy breathing during work

• Normal breathing while resting

These horses are not usually febrile unless another disease, such as bacterial pneumonia, is also present. Some horses show little more than a few coughs and unexplained loss of performance. (Merck Veterinary Manual)

In practice, this is one of the easiest forms of respiratory disease to underestimate. The horse may still compete, finish the ride and appear comfortable in the stable, but small reductions in airflow can matter considerably during harder exercise.

3. Severe Equine Asthma

Severe equine asthma was previously known as recurrent airway obstruction, heaves or broken wind.

Affected horses may show:

• Frequent coughing

• Increased breathing effort at rest

• Nostrils flaring while standing quietly

• A prolonged or forced exhalation

• Abdominal effort when breathing

• Wheezing

• Exercise intolerance

• Thick nasal mucus

• Weight loss in chronic cases

• A visible “heave line” along the abdomen

Severe asthma is a progressive inflammatory airway disease. Long-standing inflammation can remodel and narrow the airways, and some structural changes may become irreversible. (Merck Veterinary Manual)

A horse struggling to breathe at rest needs urgent veterinary care. Do not exercise the horse to assess how bad the problem is.

4. Summer Pasture-Associated Equine Asthma

Some horses develop severe asthma primarily while at pasture during warm, humid weather.

Possible environmental triggers include grass pollen, fungal spores and other seasonal airborne particles. Signs may improve when the horse is removed from pasture and housed in a carefully managed low-dust environment. This pattern has been documented most often in hot, humid regions, but can occur elsewhere. (Merck Veterinary Manual)

Clues include:

• A predictable summer pattern

• Coughing that worsens on pasture

• Increased breathing effort during hot, humid periods

• Improvement during cooler months

• Improvement when removed from the triggering environment

This is not simply a horse being “allergic to grass.” The diagnosis still requires veterinary assessment because infection, cardiac disease and other respiratory conditions can look similar.

5. Equine Influenza

Equine influenza is highly contagious and can move quickly through groups of susceptible horses.

Typical signs include:

• Sudden fever

• A frequent, harsh or dry cough

• Watery nasal discharge that may later become thicker

• Depression

• Reduced appetite

• Enlarged lymph nodes

• Poor performance

Horses showing coughing, fever or nasal discharge should be isolated immediately while infectious disease is investigated. Vaccinated horses can still develop influenza, although vaccination generally reduces disease severity and viral shedding.

A cough after a show or event should not automatically be blamed on arena dust, particularly if the horse also has a fever or other horses are affected.

6. Equine Herpesvirus

EHV-1 and EHV-4 can cause fever, nasal discharge, lethargy, reduced appetite and coughing. EHV-1 can also cause abortion, neonatal disease and the neurological condition EHM.

Fever may be the earliest or only initial sign. A horse with respiratory signs after travel or exposure should be isolated, and fever accompanied by weakness, wobbliness, urine dribbling or loss of tail tone is an emergency. (AAEP)

7. Strangles

Strangles is caused by Streptococcus equi and can produce:

• High fever

• Depression

• Thick nasal discharge

• Painful lymph node swelling

• Difficulty swallowing

• Coughing

• Abscess formation under the jaw or behind the throat

The fever commonly develops before the characteristic lymph node swelling and mucopurulent discharge. Suspected cases need isolation and veterinary testing because infected horses may spread the organism before the disease looks dramatic. (Merck Veterinary Manual)

8. Bacterial Pneumonia and Pleuropneumonia

Bacterial pneumonia may develop independently or as a complication of:

• Viral respiratory disease

• Long-distance transport

• Choke

• Aspiration

• General anaesthesia

• Swallowing dysfunction

• Severe illness

Signs may include:

• Fever

• Depression

• Reduced appetite

• Increased respiratory rate

• Shallow or painful breathing

• Soft coughing

• Nasal discharge

• Reluctance to move

• Abnormal lung sounds

• Foul-smelling breath or discharge

• Chest pain

A cough may be surprisingly mild or absent in horses with serious pleuropneumonia. Rapid, shallow breathing, depression and recent transport can be more important clues than the sound of the cough itself. Foul-smelling discharge is particularly concerning for anaerobic infection or necrotising pneumonia. (Merck Veterinary Manual)

9. Choke and Swallowing Disorders

A horse coughing during eating may simply be reacting to dusty forage. However, repeated coughing combined with swallowing difficulty must be treated differently.

Signs of choke or dysphagia include:

• Feed or water coming from the nostrils

• Heavy salivation

• Repeated coughing

• Stretching or arching the neck

• Repeated attempts to swallow

• Anxiety or distress

• Feed material around the mouth and nose

• A palpable swelling along the neck in some cases

Choke is an obstruction of the oesophagus, not the windpipe, so the horse may still breathe. The major dangers are oesophageal damage and aspiration pneumonia.

Remove all feed and water and call your veterinarian. Do not hose water into the horse’s mouth, administer oil orally or attempt to force the obstruction down. (Merck Veterinary Manual)

Pharyngeal paralysis and other swallowing disorders can produce similar signs and may be associated with guttural pouch disease, neurological disease or local injury. (Merck Veterinary Manual)

10. Exercise-Induced Pulmonary Haemorrhage

Exercise-induced pulmonary haemorrhage, or EIPH, involves bleeding into the lower airways during strenuous exercise.

It is most strongly associated with racehorses and horses performing intense high-speed work. Possible signs include:

• Poor performance

• Longer recovery

• Frequent swallowing after exercise

• Coughing after strenuous work

• Blood at the nostrils in a small minority of cases

Visible bleeding from the nostrils is uncommon. Most affected horses are diagnosed through endoscopic examination after exercise or by finding evidence of previous bleeding in bronchoalveolar lavage fluid. Coughing after work does not by itself confirm EIPH. (Merck Veterinary Manual)

Spontaneous, heavy or repeated nasal bleeding should not automatically be called EIPH. Guttural pouch mycosis, trauma, ethmoid haematoma and other potentially serious conditions must be considered.

11. Upper Airway Disorders

Dynamic upper airway disorders may only become apparent when the horse exercises at speed.

Examples include:

• Recurrent laryngeal neuropathy

• Dorsal displacement of the soft palate

• Pharyngeal collapse

• Aryepiglottic fold collapse

• Epiglottic entrapment

These conditions more commonly cause abnormal respiratory noise and reduced performance than coughing. Resting endoscopy may appear normal, so dynamic endoscopy during exercise may be needed. (Merck Veterinary Manual)

The practical distinction is useful:

• Coughing more often directs attention toward airway irritation, inflammation or infection.

• Roaring, gurgling or choking noise during exercise raises greater concern for upper airway obstruction.

A horse can, of course, have both. Horses do enjoy making diagnostic problems a group project.

12. Less Common Causes

Other causes of coughing include:

• Lungworm, particularly in horses grazing with donkeys

• Migrating parasites in young horses

• Fungal pneumonia

• Equine multinodular pulmonary fibrosis

• Smoke or chemical inhalation

• Thoracic trauma

• Heart failure

• Lung masses

• Foreign material within the airway

• Guttural pouch disease

• Sinus or dental disease

• Aspiration associated with neurological dysfunction

Current AAEP respiratory guidelines include infectious, inflammatory, parasitic, cardiac, neoplastic, toxic and traumatic conditions among the recognised differentials for acute respiratory signs.

What Does Nasal Discharge Mean?

Nasal discharge provides useful clues, but colour alone does not provide a diagnosis.

Clear or Watery Discharge

Clear discharge may occur with:

• Early viral respiratory infection

• Environmental irritation

• Exercise

• Equine asthma

• Normal temporary airway moisture

A clear runny nose does not automatically mean allergy, particularly if the horse has a fever, cough or recent infectious exposure.

White or Mucoid Discharge

White or cloudy mucus may occur with chronic airway inflammation, asthma, viral disease or accumulated respiratory secretions.

Yellow or Green Discharge

Yellow or green discharge contains inflammatory material and may occur with:

• Bacterial infection

• Secondary bacterial infection after a virus

• Strangles

• Pneumonia

• Guttural pouch infection

• Sinus or dental disease

It increases concern, particularly when accompanied by fever, depression or foul odour, but it does not automatically identify the organism or prove that antibiotics are required.

Discharge From One Nostril

Persistent one-sided discharge points more toward a local problem, such as:

• Sinusitis

• Dental infection

• Nasal mass

• Guttural pouch disease

• Foreign material

• Ethmoid haematoma

Sinus disease commonly produces unilateral purulent, bloody or malodorous discharge. (Merck Veterinary Manual)

Discharge From Both Nostrils

Bilateral discharge is more consistent with disease affecting the pharynx, trachea or lungs, including viral infection, asthma or pneumonia.

Foul-Smelling Discharge

A strong foul smell is concerning for:

• Anaerobic bacterial pneumonia

• Necrotising lung infection

• Dental sinusitis

• Guttural pouch infection

• Retained infected material

This needs prompt veterinary assessment. (Merck Veterinary Manual)

Feed or Water From the Nose

This is not ordinary nasal discharge. It suggests choke or impaired swallowing and requires urgent veterinary attention. (Merck Veterinary Manual)

How Worried Should You Be?

Low Concern

This may include:

• One isolated cough

• No fever

• Normal appetite

• Normal behaviour

• Normal breathing at rest

• No nasal discharge

• No recent travel or known exposure

• No recurrence during exercise or feeding

What to do: record when it happened and monitor closely for the next 12 to 24 hours. Check the horse’s resting temperature. Reduce obvious dust exposure.

If the cough recurs, particularly during exercise, arrange a veterinary assessment.

Moderate Concern

This includes:

• Several coughs during a ride

• Recurrent coughing while eating

• Coughing that returns over multiple days

• Mild nasal discharge

• Reduced stamina

• Slower recovery after exercise

• No fever or breathing difficulty at rest

What to do: stop intense work, check temperature at least twice daily and arrange a veterinary examination. Review hay, bedding, ventilation and stable dust while waiting.

A cough that appears during most exercise sessions should not be managed indefinitely by simply warming the horse up for longer.

High Concern

This includes:

• Resting temperature of 101.5°F or 38.6°C or higher

• Coughing after travel or competition

• Several horses coughing

• Thick nasal discharge

• Depression or reduced appetite

• Increased breathing rate at rest

• Persistent cough beyond 24 to 48 hours

• Painful or swollen lymph nodes

• Recent choke

• Recent long-distance transport

What to do: isolate the horse and contact your veterinarian the same day. Avoid sharing buckets, tack, thermometers, grooming equipment or airspace where possible.

Critical

This includes:

• Laboured breathing at rest

• Blue or grey gums

• Severe abdominal breathing effort

• Feed or water from the nostrils

• Collapse

• Major nasal bleeding

• Rapid deterioration

• Severe illness after transport

• Fever with neurological abnormalities

• Inability to swallow

• Suspected aspiration pneumonia

What to do: seek emergency veterinary care immediately.

How Do Vets Diagnose the Cause?

The most useful information often starts with the history.

Your veterinarian may ask:

• When did the coughing begin?

• Does it occur at rest, while eating or during exercise?

• Has the horse travelled recently?

• Are other horses affected?

• What is the vaccination history?

• Has the forage, bedding or stable environment changed?

• Is there nasal discharge?

• Is the discharge from one nostril or both?

• Has performance changed?

• Has there been choke, sedation or anaesthesia?

• Is the problem seasonal?

• Does the horse improve when kept outside or away from hay?

Physical and Respiratory Examination

The examination may include:

• Rectal temperature

• Resting respiratory rate and effort

• Nasal airflow

• Lymph node assessment

• Tracheal and lung auscultation

• Sinus percussion

• Examination for abnormal respiratory noise

• Rebreathing examination, but only when the horse is not in respiratory distress

AAEP diagnostic guidance also recommends considering recent travel, vaccination, environmental changes, donkey exposure and parasite history.

Nasal Swabs and PCR

PCR testing may be used to investigate:

• Equine influenza

• EHV-1 and EHV-4

• Strangles

• Equine rhinitis viruses

• Other infectious respiratory pathogens

Testing is most useful when samples are collected at the appropriate stage of illness. The horse should be isolated while waiting for results if contagious disease is possible.

Endoscopy

Endoscopy allows examination of:

• Nasal passages

• Pharynx

• Larynx

• Guttural pouches

• Trachea

• Airway mucus

• Blood associated with EIPH

Dynamic endoscopy during exercise may be needed when abnormal noise or performance loss occurs only during work.

Tracheal Wash

A tracheal wash collects material from the trachea and is particularly useful when bacterial lower respiratory infection is suspected.

The sample can be used for:

• Cytology

• Bacterial culture

• Antimicrobial susceptibility testing

Bronchoalveolar Lavage

Bronchoalveolar lavage, commonly called a BAL, collects cells and fluid from the smaller lower airways.

BAL cytology is the principal test for confirming and characterising equine asthma. It can also provide evidence of previous pulmonary bleeding. BAL is not appropriate in every horse, particularly one experiencing uncontrolled respiratory distress at rest. (Merck Veterinary Manual)

Thoracic Ultrasound and Radiographs

Imaging may help detect:

• Pneumonia

• Pleural fluid

• Lung consolidation

• Abscessation

• Pulmonary fibrosis

• Masses

• Other structural disease

Thoracic ultrasound is particularly useful for examining the surface of the lungs and pleural space.

Blood Testing

A complete blood count and inflammatory markers may support a diagnosis of infection or inflammation, although normal blood results do not rule out equine asthma.

Does a Coughing Horse Need Antibiotics?

Not automatically.

Antibiotics do not treat:

• Equine influenza

• EHV

• Equine asthma

• Dust irritation

• Most uncomplicated viral respiratory infections

• EIPH

• Dynamic upper airway obstruction

Antibiotics may be needed when there is evidence of:

• Bacterial pneumonia

• Pleuropneumonia

• Aspiration pneumonia

• Strangles complications

• Bacterial sinusitis

• Guttural pouch empyema

• Secondary bacterial infection after viral disease

Starting antibiotics before examination and appropriate sampling can reduce diagnostic yield and may result in the wrong drug being used.

The cough is not the diagnosis. Treating every cough with antibiotics is a bit like treating every limp with the same horseshoe.

How Is Equine Asthma Treated?

Treatment usually combines environmental management with veterinary-prescribed medication.

Environmental Management

This is the most important long-term component.

Possible changes include:

• Replacing dusty hay with a genuinely low-dust forage

• Properly steaming hay

• Soaking hay when appropriate and managing it hygienically

• Feeding from ground level when safe

• Improving stable ventilation

• Removing the horse while sweeping or blowing aisles

• Avoiding hay storage above the stable

• Changing dusty bedding

• Avoiding round bales in affected horses

• Reducing arena dust

• Limiting exposure to smoke, ammonia and pollutants

Some horses improve dramatically after environmental change. Medication may control signs temporarily, but signs commonly return when the horse remains in the same allergen-rich environment. (Merck Veterinary Manual)

Corticosteroids

Systemic or inhaled corticosteroids may be prescribed to control airway inflammation.

These should only be used after appropriate veterinary assessment. Corticosteroids can suppress fever and inflammatory signs, and their use in a horse with unrecognised infection can complicate the situation.

Bronchodilators

Bronchodilators can rapidly improve airflow in selected horses, but they do not control the underlying inflammation and should not be used as the sole treatment for equine asthma. (Merck Veterinary Manual)

What Should You Do Right Now?

If your horse has started coughing:

1. Stop strenuous exercise.
   Do not continue galloping or jumping to see whether the horse “works through it.”

2. Take a rectal temperature at rest.
   Allow the horse to cool after exercise before interpreting the reading.

3. Watch the horse breathe while standing quietly.
   Look for nostril flare, abdominal effort, prolonged exhalation or a rising respiratory rate.

4. Check appetite and demeanour.
   A bright horse eating normally is less concerning than a dull horse refusing feed.

5. Look at the nasal discharge.
   Note whether it is clear, thick, foul-smelling, bloody, one-sided or bilateral.

6. Identify when the coughing occurs.
   Record whether it happens with hay, at warm-up, throughout exercise, after transport or while resting.

7. Check the other horses.
   Multiple coughing horses make infectious disease more likely.

8. Isolate if infection is possible.
   Fever, recent travel, nasal discharge or other affected horses should trigger immediate separation.

9. Record a video.
   A short recording of the cough, breathing effort or exercise noise can be useful for your veterinarian.

10. Call urgently if the horse worsens.
    Do not wait overnight if breathing becomes difficult, feed appears at the nostrils or the horse becomes depressed.

Common Mistakes Horse Owners Make

Assuming a Warm-Up Cough Is Normal

A single cough can happen. Repeated coughing during most rides suggests mucus or airway inflammation and deserves investigation.

Relying Only on Mucus Colour

Clear discharge can occur with viral infection, and yellow discharge does not automatically prove primary bacterial disease. Temperature, laterality, smell and the horse’s overall condition matter more.

Waiting for a Very High Fever

A temperature does not need to reach 102.5°F before it matters. A resting temperature of 101.5°F or higher, especially following travel or exposure, is enough to justify isolation and veterinary advice. (AAEP)

Continuing to Exercise the Horse

Working through respiratory inflammation can prolong recovery and worsen airway irritation.

Starting Leftover Antibiotics

The cough may be viral, inflammatory, mechanical or exercise-related. Using the wrong antibiotic delays diagnosis and contributes to antimicrobial resistance.

Treating Asthma Without Changing the Environment

Medication cannot permanently outrun a dusty stable and allergen-rich forage.

Missing Choke

A horse coughing during eating with feed or saliva at the nostrils is not simply reacting to dusty hay.

Assuming Every Post-Exercise Cough Is EIPH

EIPH requires appropriate diagnostic evidence. Asthma and airway mucus are also common causes of exercise-associated coughing.

How Can Coughing and Respiratory Disease Be Prevented?

Not every respiratory problem can be prevented, but risk can be reduced.

Practical steps include:

• Maintain appropriate influenza and EHV vaccination

• Isolate new and returning horses

• Take temperatures after travel

• Avoid shared water buckets

• Do not submerge communal hoses in buckets

• Improve stable ventilation

• Reduce respirable dust

• Use low-dust forage and bedding

• Avoid sweeping around stabled horses

• Keep hay storage away from breathing zones

• Address arena dust

• Investigate repeated exercise coughing early

• Manage choke and dental risk

• Allow horses to lower their heads during transport where safe

• Stop travelling or competing horses showing respiratory signs

AAEP recommends immediate isolation of horses with coughing, nasal discharge or fever. Horses returning from shows or similar events should be separated and monitored for at least 14 days under influenza biosecurity guidance, with longer periods appropriate for some EHV risks.

Will My Horse Be Okay?

Most horses with mild irritation, uncomplicated viral infection or well-managed mild asthma recover or return to useful work.

The outlook depends on the cause.

The prognosis is generally better when:

• The problem is identified early

• Breathing remains normal at rest

• There is no pneumonia

• The environment can be improved

• Infection is isolated quickly

• The horse receives adequate rest

• Choke is resolved before significant aspiration occurs

• Asthma has not caused major permanent airway remodelling

The outlook becomes more guarded when:

• Severe breathing difficulty is present

• Pneumonia or pleuropneumonia develops

• Aspiration has occurred

• Severe asthma has been present for years

• The horse continues to be exposed to the trigger

• There is significant swallowing dysfunction

• The horse deteriorates after transport

• Diagnosis and treatment are delayed

The earlier recurring cough is investigated, the better the chance of managing the disease before it becomes a larger welfare or performance problem.

FAQs About Coughing in Horses

Should I ride my horse if they are coughing?

Do not undertake strenuous exercise until you know why the horse is coughing. One isolated cough may not require extended rest, but recurrent coughing during work, fever, discharge or reduced performance warrants stopping exercise and arranging an assessment.

How long should I monitor an occasional cough?

A single cough in an otherwise normal horse can be monitored for 12 to 24 hours. Check temperature and breathing. Contact your vet if the cough recurs, continues into the next day or appears during exercise.

Does clear nasal discharge mean allergies?

No. Clear discharge can occur with environmental irritation, exercise, asthma or early viral infection. Fever, exposure history and other signs help distinguish the cause.

Does yellow or green mucus mean my horse needs antibiotics?

Not necessarily. Thick coloured discharge increases concern for infection or accumulated inflammatory material, but colour alone does not determine the cause or correct treatment.

Can dusty hay make a horse cough?

Yes. Hay dust, mould particles and other respirable material can trigger temporary irritation or contribute to equine asthma. Repeated hay-associated coughing should not simply be accepted as normal.

Is coughing after exercise a sign of bleeding in the lungs?

It can occur with EIPH, but asthma, mucus and airway irritation are also common. EIPH is usually diagnosed through post-exercise endoscopy or airway fluid analysis rather than coughing alone. (Merck Veterinary Manual)

Final Thoughts

A cough is not a diagnosis. It is the respiratory system telling you that something has irritated, inflamed, obstructed or entered the airway.

The main questions are:

• Is the horse febrile?

• Is breathing normal at rest?

• Does the cough recur?

• Does it happen while eating or exercising?

• Has the horse recently travelled?

• Are other horses affected?

• Is there nasal discharge, and what does it look and smell like?

• Has performance changed?

One isolated cough may mean very little. A repeated cough, especially during exercise, is not something to normalise. Fever, breathing difficulty, feed from the nostrils or rapid deterioration changes the situation completely.

Check the temperature, stop hard work, isolate when infection is possible and investigate the pattern rather than guessing from the sound of the cough.

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If you are unsure whether your horse’s cough can be monitored or needs urgent attention, ASK A VET™ can help you review the pattern, temperature, respiratory signs and recent history while your local veterinarian provides examination and treatment when hands-on care is needed.