Why is My Horse Coughing?

Updated December 15, 2023 | By: Dr. Jamie Whittenburg, DVM

Just like with people, horses will cough occasionally and usually there is no further issue. Coughing serves to clear the airways of small debris and irritants.

However, if a horse is repeatedly having coughing episodes, has other signs of illness, or is having respiratory difficulty, she needs prompt veterinary attention. It is important to be able to recognize differences in coughs and possible causes so that you can provide your horse with the necessary care.

What Causes a Horse to Cough?

Horses may cough for many different reasons, some of which may be benign, while others could be serious. Noting when the coughing is occurring can help in determining what type of cough it is and get to the root of the underlying cause.

Exercise Induced Cough

It is common for a horse to cough a few times at the beginning of a workout. This may happen when warming up or when your horse exerts herself upon being released into a pasture. Her coughing should not last longer than a few minutes and it should resolve with continued exercise.

Persistent coughing or a wet, productive cough is cause for concern. This may indicate laryngeal hemiplegia (commonly called roaring), exercise induced pulmonary hemorrhage, or pneumonia. If continued exercise worsens the coughing, or if any breathing difficulty like wheezing is seen, call your veterinarian.

Coughing During Eating

A momentary cough while eating can often be normal. Dust from hay can irritate the airways as the horse initially begins to eat. However, repeated coughing, choking, or difficulty swallowing that results in a cough are cause for concern.

If the cough is persistent while the horse is eating, common causes include:

• excessive dust in the hay or feed
• heaves
• allergies
• a respiratory infection
• dental disease

These potential causes should be addressed as soon as possible with the help of your veterinarian.

Travel Induced Cough

When horses travel, they are exposed to both infectious agents and stress. Additionally, horses are often unable to lower their heads as they normally would when tied inside a trailer, which can result in debris getting trapped in their lungs.

This combination can lead to contagious respiratory diseases, commonly known as shipping fever. These infections are most often caused by viruses but can involve bacteria as well. A veterinarian should examine your horse if she is coughing and has recently traveled.

Upper and Lower Respiratory Infections

Respiratory infections can occur in horses at any time in their lives, not just after travel. Like people, horses can contract both viral and bacterial infections. The most common signs you may see in your coughing horse that may indicate a respiratory infection include:

• fever (body temperature above 101.5 degrees Fahrenheit)
• mucous or nasal discharge
• decreased appetite
• lethargy or a reluctance to be as active as normal

Seeing these signs should prompt a call to your vet. It is important to note that the absence of fever does not definitively rule out a respiratory infection.

Allergic Cough

Some horses that have allergies or Inflammatory Airway Disease (IAD) may cough when exposed to allergens, such as hay, grass, dust, sawdust, or smoke. The lungs have an inflammatory response to the allergen’s stimulation which results in coughing.

Generally seen in older horses, Recurrent Airway Obstruction (RAO), also called heaves, is a more common airway disorder. Though this condition is also commonly triggered by an inflammatory reaction to an inhaled allergen, horses with heaves have difficulty breathing while at rest. Owners may note a persistent cough and an exaggerated contraction of the abdominal muscles when the horse exhales.

These disorders differ in that a horse with IAD will not show increased respiratory effort while at rest, and oftentimes these horses tend to be younger than those with RAO.

Coughs in Foals

A special case for concern is a cough in a very young horse or foal. Young horses are at increased risk of serious disease and death from pneumonia. Anatomical abnormalities, such as a cleft palate, can also cause recurrent coughing in foals and can quickly lead to aspiration pneumonia. A foal with a cough should be evaluated by a veterinarian as soon as possible.

Diagnostics Veterinarians May Use for Coughing Horses

Your veterinarian will first ask for a complete history of your horse. They will ask about the timing of the cough, its severity, your horse’s travel history, vaccination status, and what she is being fed. It can be helpful to have a video of your horse’s coughing episode to show your vet, as she may not be coughing at the time of examination.

The next step will be a thorough physical examination as well as taking your horse’s temperature. Blood work may be performed to assess your horse’s general health and to look for inflammatory markers. If parasites are suspected, a fecal egg count may be done.

Further diagnostics may be warranted if those basic tests cannot determine the cause or severity of your horse’s condition. Advanced diagnostics may include:

• Ultrasound - If fluid is heard in or around the lungs, ultrasound may be utilized as a noninvasive way to examine the lungs. An ultrasound will enable your veterinarian to visualize the lungs and identify if areas of the lungs are non-aerated or have pockets of excess fluid.
• Secretion Sampling - If a sample of the material and cells in the respiratory tract is needed, your veterinarian may perform a trans tracheal wash (TTW) or a bronchoalveolar lavage (BAL). Typically, a TTW will be used to find infectious causes, whereas a BAL is used to examine the cells in the lungs for signs of inflammatory disease.
• Endoscopy – An endoscopic exam entails passing a long thin camera into the horse’s nose and airway. The camera enables your veterinarian to visualize the nasal passages, guttural pouches, trachea, and upper airways. Often this test is required to identify anatomical abnormalities.

Treatment for Coughing in Horses

Appropriate treatment will largely depend on the cause and the case’s severity. Working closely with your veterinarian from the first sign of symptoms is key to having a successful outcome for your horse.

Environmental changes such as reducing dust in the barn and stall bedding, wetting or steaming your horse’s hay, and not letting her out into dusty paddocks or pastures can help alleviate symptoms.

Coughs caused by infections may require antibiotics, and horses with parasites will need to be dewormed. Allergic airway diseases can also be treated with specific anti-inflammatory medicines, immunotherapy, or inhaled medications such as bronchodilators. These medications are often delivered via a spacer or nebulizer.

Although rare, a horse with a severe condition, like pneumonia, will need to be hospitalized so she can receive aggressive treatment. Anatomical issues, like paralysis of the larynx seen in cases of roaring, may require surgery.

Supplements That May Lend Respiratory Support

In some cases, especially those caused by allergies, there may be a nutritional supplement that can help your horse. Some ingredients to look for in supplements to support your horse’s respiratory system include:

• Omega 3 Fatty Acids – Research has found that feeding the essential omega-3 fatty acid DHA can improve lung function and decrease inflammation in the airways of horses with respiratory issues [1].
• MSM - A potent antioxidant, MSM may be beneficial for horses with seasonal allergic reactions on the skin or in the respiratory tract.
• Mushrooms – Certain mushrooms, like cordyceps and reishi, are rich in antioxidants, may support a normal inflammatory response and healthy immune function.
• Vitamin C – Another key antioxidant, Vitamin C works in combination with Vitamins A and E to protect tissues of the respiratory system as well as the connective tissues in joints, skin, hooves, and teeth.
• Whole-Food Extracts and Adaptogenic Botanicals – There are reported benefits for herbs, such as American and Siberian Ginseng, that can modulate the horse’s response to stressors and regulate the immune system [2]. Ingredients like ashwagandha root extract [3] and turmeric (curcumin) work to combat oxidative stress in the body. Additionally, spirulina and jiaogulan may support respiratory function and skin health [4].

Prognosis for a Coughing Horse

Many horses will occasionally cough, and that can be quite normal. A cough that is persistent, wet, and produces mucus, causes respiratory difficulty, or affects a very young horse, should be addressed as soon as possible by a veterinarian.

In horses affected by a disease, a prognosis is dependent on the underlying cause. Your veterinarian will work with you to find solutions to help your horse breathe easier.

Questions Horse Owners Frequently Ask

Can Worms in Horses Cause Coughing?

Yes, certain parasites, such as roundworms and lungworms, can cause a horse to cough. Worms are especially prevalent in younger horses. All horses should follow a basic deworming program with additional targeted treatments for medium and high egg-shedders.

Why Does My Horse Have a Sudden Dry Cough?

A sudden dry cough can be normal from time to time, such as at the beginning of exercise. The horse uses a quick cough to clear her airways of debris and mucus. However, if the cough is persistent, there may be an underlying issue.

Ask the Vet Video on Coughing During Warm Up

In this video, Dr. Lydia Gray sheds light on a rider’s question about a horse that coughs and sneezes constantly when warming up under saddle.

Evidence-Based References

1. Nogradi, N., Couetil, L. L., Messick, J., Stochelski, M. A., & Burgess, J. R. (2015). Omega-3 fatty acid supplementation provides an additional benefit to a low-dust diet in the management of horses with chronic lower airway inflammatory disease. Journal of veterinary internal medicine, 29(1), 299–306.
2. Maimes, Steven. (2007). Adaptogens: Herbs for Strength, Stamina, and Stress Relief.
3. Priyanka G., Anil Kumar B., Lakshman M., Manvitha V., Kala Kumar B. (2020). Adaptogenic and Immunomodulatory Activity of Ashwagandha Root Extract: An Experimental Study in an Equine Model. Frontiers in Veterinary Science, volume 7.
4. Kellon, Eleanor. “Use of the Herb Gynostemma Pentaphyllum and the Blue-green Algae Spirulina Platensis in Horses [PDF].” (2006).