“ROARERS” (LARYNGEAL HEMIPLEGIA)

Many people involved with performance horses have come across the term “roarer”, but some may be unaware what this actually entails.

In the normal horse the larynx acts as a “gateway” to both the trachea (“windpipe”) and the oesophagus (“food pipe”). The cartilages of the larynx open with exercise to allow for maximal air intake and are capable of closing to prevent food or water entering the airways during swallowing.

In “roarers”, one side (usually the left) of the larynx is not able to fully open due to nerve damage resulting in paralysis of the muscles responsible for pulling the laryngeal cartilages into the open position. This means that instead of the airway becoming wider with vigorous exercise it actually narrows as the paralysed cartilage is pulled into the airway by negative pressure. It is this cartilage flapping in the airway that results in the “roar” or whistle heard as horses breathe in.

A good rider or driver can hear that the noise occurs as the horse inspires. This can help differentiate from noises associated with problems occurring during expiration (eg displaced soft palate).

The diagnosis is usually confirmed by endoscopy in order to visualise the problem. Some horses with low level workloads may cope very well with reduced function of their larynx, however those that perform high intensity exercise usually require surgery if they are to continue to compete.

At Riverdene, surgery is performed by specialist equine surgeon Dr Nick Kannigieter. Surgery involves a combination of a “tie back” where the offending cartilage is sutured back into the “open” position and a “ventriculectomy” where the vocal cord is encouraged to scar outwardly.

While this procedure can be very successful, it is not without potential complications. These include: suture pull through, infection, wound problems, coughing, food aspiration etc.

Horses that have had tie back surgery for roaring should be fed at ground level for the rest of their lives to minimise the risk of aspiration of food material.

If you have any concerns about your horse’s respiratory system, exercise tolerance or performance level, please feel free to contact us at the clinic to discuss this further.