Roaring (Laryngeal Paralysis) in Horses - Causes, Treatment and Associated Conditions

Key takeaways

A horse which groans excessively or ‘roars’ during exercise may have laryngeal paralysis.

This condition is caused by damage to a nerve inside the neck which controls the opening of the throat
In laryngeal paralysis, the throat (larynx) is unable to open fully, causing noise as the horse inhales and exhales through a smaller airway
Laryngeal paralysis is not life-threatening, and is more common among taller male horses and racehorses
Injury or toxicosis may result in roaring, however in general the underlying causes of laryngeal paralysis are not well understood
Diagnostics include a physical examination, ultrasound, and a range of endoscopies
Treatment is not always necessary, especially in less active horses
Horses experiencing poor performance or exercise intolerance may require retirement, unless further treatment is pursued
Surgical correction is possible; prognosis after surgery is variable

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A closer look: Roaring (Laryngeal Paralysis) in Horses

The larynx is the airway within the throat. “Roaring” noises may be heard from horses when control of this opening is compromised, reducing the airflow through the larynx. In most cases, this is associated with paralysis of one of the nerves within the throat.

Laryngeal paralysis is not life-threatening, and horses with a less intense workload may never require treatment.

Horses with more intense exercise regimes, such as racehorses, may benefit from surgery to improve performance.

Risk factors

This is due to their inability to intake oxygen properly.

Laryngeal paralysis occurs more commonly in some breeds, such as Thoroughbreds and Warmbloods, suggesting a genetic inheritance. Tall male horses are also predisposed to developing this condition.

Possible causes

The larynx is the entry point to the windpipe, located at the top of the throat. In a healthy horse, the larynx opens and closes regularly during breathing. Laryngeal paralysis affects the nerves responsible for opening the larynx, causing cartilage to partially block the airway.

The cause of this condition is often unknown. In addition to breed disposition, other suspected causes include toxicosis and injury or as a complication of surgery in the neck or throat region.

Main symptoms

Testing and diagnosis

Diagnostics include:

A physical exam
Ultrasound
Endoscopy to visualize the larynx
Dynamic endoscopy, to visualize the function of the larynx during exercise

Steps to Recovery

Treatment is not always necessary. In cases where no exercise intolerance is present and owners are willing to tolerate the noise, no treatment is needed. In cases with poor performance, a reduced workload is often sufficient to maintain quality of life. In cases where maintaining previous levels of performance is desired, surgery is indicated to open the airway. Surgical intervention often requires additional follow up appointments to monitor recovery and ensure the larynx is healing appropriately.

Laryngeal paralysis is a lifelong condition, although a good quality of life is often attainable without treatment. In some cases, the condition’s severity progresses over time, requiring retirement from performance or surgery.

Prognosis for surgical intervention varies. An operation may not completely reverse the paralysis, and horses performing intense exercise (such as a race horse) may still require retirement or changes in activity.

Prevention

Avoiding breeding an affected horse may prevent laryngeal paralysis from being passed on to subsequent generations. Otherwise there are no effective methods for preventing laryngeal paralysis.