Introduction

Some horses, while they are working, sound very raspy when they breathe. If it happens only occasionally, it may only be a bit of congestion, or it could signal the start of a 'cold' or other problem. However, if the horse does not show signs of a respiratory ailment, it may be 'roaring'. The sound may be guttural, or more of a whistling or wheezing sound. Roaring isn't unusual, although it is a concern since the condition may affect the horse's performance.

Other Names for Roaring:

The horse may be referred to as a roarer or whistler. The condition may also be called whistling, Recurrent Laryngeal Neuropathy, RLN, or less often, laryngeal hemiplegia or laryngeal paralysis, which describes specific conditions within the broader condition of RLN.

Causes:

Roaring happens because the horse's airway is restricted through the larynx or 'voice box'. It is more common in larger horses, and the left side of the larynx is most often affected. Nerve damage is at the root of the problem, and that may have to do with how the nerve pathway to the area is routed. This causes the muscle to atrophy, or become flabby. As the air rushes past the slack larynx muscle, it makes a roaring, wheezing or whistling sound. Over time, as the muscle becomes weaker and weaker, the problem may become more severe, so that the horse's breathing is compromised severely. Some horses may stabilize however, and the problem may be annoying, but may not cause a decrease in performance.

Symptoms:

You may hear your horse roaring more when working your horse at the trot or canter, or any time it is working hard enough that its TPRs increases. Your horse may tire more easily. It may not be noticeable when your horse is at rest. There are no other symptoms with roaring as there would be with a viral infection, such as poor appetite or fever. If the horse works out of the noise, it may have cleared some congestion such as can be caused by hay dust. Roaring does not go away with exercise.

Diagnoses:

Your veterinarian will help you diagnose roaring. The vet will check for muscle loss in the larnyx. An internal examination using an endoscope, a tiny camera on a flexible arm, can be used to thoroughly examine the area. The vet will take note of any differences in the right and left side of the larnyx. By holding the nostrils closed, the vet will be able to observe how the two sides of the larnyx work as the horse tries to inhale and exhale. The horse may be put on a treadmill so that its breathing can be observed at a working level. Endoscopic examination can also rule out other problems like cysts, inflamed lymph nodes, infection, inflammation, tumors, or other problems that may be causing the roaring.

Treatment:

There are several surgical options to repair the damaged muscles. These include removing damaged tissue, supporting the muscle in various ways such as sutures or grafts, or placing a tube through the larynx that holds the trachea open. All options come with some risk, such as the aspiration of feed, and none are 100% guaranteed to return a horse to its optimum performance level. If you do not opt for surgery, you may have to decrease your horse's workload to keep it comfortable. Many horses used for light riding may live comfortably without surgery.

Prevention:

Unfortunately, there is no way to prevent your horse from roaring. There is some evidence that suggests that the condition may be hereditary.