Equine Respiratory 101: Why is my horse coughing and what does it mean?

Horse standing in grass near stable.

Recurrent airway obstruction (RAO).

Equine chronic obstructive pulmonary disease (COPD).

Inflammatory airway disease (IAD).

Chronic bronchitis.

Summer heaves.

Equine asthma syndrome.

With so many terms used to describe non-infectious inflammatory airway disease in horses, it’s no wonder horse owners find themselves confused. But because chronic respiratory diseases can make breathing difficult and lead to poor performance and general health deterioration, identifying and treating it is critical.1 

The most serious of these respiratory conditions is equine asthma. A horse suffering from severe equine asthma experiences a narrowing and/or obstruction in the airway passages. Identifying equine asthma early is important because without diagnosis and treatment, the condition can have a long-term impact on the lungs.

The term equine asthma has recently been divided into mild-moderate (IAD) and severe (Heaves, RAO, and SPRAO).

Severe equine asthma affects 14% - 17% of horses in countries with a northern cool climate, with typical onset of signs beginning in horses seven years or older. The clinical signs are:

  • Increased respiratory effort at rest
  • Associated with frequent coughing
  • Exercise intolerance
  • Marked lower airway inflammation and obstruction2

Mild/moderate asthma may affect up to 68%-80% of racehorses.3 They display these clinical signs:

  • Respiratory effort generally normal at rest
  • Poor performance
  • Coughing in 38% of horses

“Horses with mild equine asthma don’t always present noticeable clinical signs,” says Steve Grubbs, DVM, PhD, DACVIM, Technical Manager, Boehringer Ingelheim. “But a horse with severe equine asthma will most likely have labored breathing, even when the horse is at rest.” 

The most effective therapy for severe equine asthma is a combination of environmental management, glucocorticoids and bronchodilators.3

The Aservo® EquiHaler® (ciclesonide inhalation spray) is indicated for the management of clinical signs associated with severe equine asthma in horses. The drug is delivered through an inhaler featuring an ergonomic handle and dosing lever, making it simple to administer. An anatomically designed nostril adaptor fits inside the left nostril of the horse, making it easy for them to inhale the medicated mist. 

Studied in over 600 horses with severe equine asthma, those treated with ASERVO EQUIHALER demonstrated improved lung function and clinical signs. In addition, ASERVO EQUIHALER demonstrates reduced risk of the side effects often associated with cortisol suppression secondary to administration of other glucocorticoids.4

“It’s important for horse owners to be vigilant and observant when it comes to identifying a potential respiratory issue,” says Dr. Grubbs. For more information, visit ASERVOEQUIHALER.com.


IMPORTANT SAFETY INFORMATION: ASERVO EQUIHALER has not been evaluated in pregnant or lactating mares. In a large clinical field study, the most common adverse reactions reported were coughing, nasal discharge, sneezing, and nasal irritation/bleeding. Administration of corticosteroids may worsen existing bacterial, fungal, or viral infection. Glucocorticoids should be used with caution in horses with a history of laminitis, or at a higher risk for laminitis. Not for use in humans.



1Couetil LL, Cardwell VG, Gerber V et. Al. Inflammatory Airway Disease of Horses-Revised Consensus Statement. J. Vet Intern Med. 2016;30:503-515.

2House A. Recurrent Airway Obstruction (RAO) in the Horse. AAEP, 2016. Accessed April 24, 2022. https://aaep.org/horsehealth/recurrent-airway-obstruction-rao-horse.

3Allen KJ, Tremaine WH, Franklin SH. Prevalence of inflammatory airway disease in National Hunt horses referred for investigation of poor athletic performance. Equine vet. J., Suppl. 36(2006) 529-534.

4Lavoie JP, Bullone M, Rodrigues N, Germin P, Albrecht B and von Salis-Sogolio M, 2019. Effect of different doses of inhaled ciclesonide on lung function, clinical signs related to airflow limitation and serum cortisol levels in horses with experimentally induced mild to severe airway obstruction. Equine Veterinary Journal.


ASERVO® and EQUIHALER® are registered trademarks of Boehringer Ingelheim Vetmedica GmbH, used under license. ©2023 Boehringer Ingelheim Animal Health USA Inc., Duluth, GA. All Rights Reserved. US-EQU-0151-2023