The two most common reasons why horses cough are respiratory infection and recurrent airway obstruction (RAO), also known as heaves:

Respiratory infection

Horses are subject to viral respiratory infections including equine influenza and rhinopneumonitis. Along with a harsh, dry cough, a horse suffering from influenza may run a fever, have a runny nose, lose his appetite, be depressed, and exhibit muscle stiffness (similar to how you feel when you have the flu!) Rhinopneumonitis symptoms are similar.

It may not be clear which virus is affecting your horse without your veterinarian running laboratory tests, and unless your horse is a mare in foal (the rhinopneumonitis virus can cause abortion in pregnant mares), is extremely sick or develops complications, it probably doesn’t make much difference. Since both are contagious, however, a sick horse should be isolated from others in the barn until his symptoms have disappeared.

Most horses recover from respiratory infection with a few weeks’ rest, a dustfree environment, clean water, good
food and plenty of TLC. Complications include bacterial infections such sinusitis, bronchitis, and pneumonia. If your horse seems to be getting better, only to relapse with a persistent cough and yucky yellowgreen sputum (the substance he coughs up) or nasal discharge, he could have a secondary infection needing antibiotic treatment. For both equine influenza and rhinopneumonitis, the best medicine is prevention: ask your vet to put your horse on a vaccination schedule.


Heaves is a chronic condition similar to asthma in humans. It is most often seen in stabled horses exposed to irritants such as dust, mold, and ammonia from urine and manure. Symptoms may come and go and include a dry cough (especially at the start of exercise), wheezing, increased respiratory rate, flared nostrils, and slight nasal discharge. Increased efforts to exhale may eventually cause the horse to develop a “heave line” (a groove running along the abdominal muscles from the flank to the lower edge of the ribs).

Symptoms can begin between a halfhour to several hours after the horse is exposed to the cause. Your vet may need
to treat severe or frequent attacks with medication (an anti-inflammatory and/or bronchodilator). Day-to-day care, however, consists mostly of controlling your horse’s environment. Turn him out on pasture as much as possible. Keep his stall clean, and use dust-free wood shavings or peat moss rather than straw or sawdust as bedding. Make sure the stable has good ventilation. Offer your horse dampened hay. If that doesn’t help, try replacing his ration of hay with pelleted feed or moistened hay cubes.

Treating the cough

Cough, cold, and allergy remedies probably line an entire shelf at your local tack shop. While none of them will cure
your horse, they may ease his symptoms somewhat. Read the labels carefully, and talk to your vet before giving your horse any cough remedy.

Further options for treating your horse’s cough include homeopathy and aromatherapy. Oral homeopathic remedies
vary depending on the cause and type of cough (dry, raspy, wet with thick sputum, etc.) and should be prepared by a trained practitioner. Aromatherapy consists of having your horse inhale specific essential oils such as eucalyptus, lavender, pine, or tea tree. An easy way to do this is to place a few drops (6-8 drops) of essential oil in a shallow bowl of warm water and hold it under your horse’s nose for a few minutes while he inhales the vapour.

Finally, remember that cough syrups and natural or homeopathic remedies should never replace veterinary care. Call your vet first if your horse has a fever, a serious case of heaves, or a cough that just won’t go away.