Roaring in Horses (Laryngeal Neuropathy)

What is Roaring in Horses? 

Roaring in horses, or in medical terms, Laryngeal Neuropathy, is a very well documented and common disease seen in horses worldwide and affects the upper airways. It can affect any horse breed but is most commonly seen in warm-blooded horse breeds aged two to six years old. 

It is a disease that causes a very characteristic “whistling” or “roaring” sound when the horse breathes, often during exercise, due to part of the larynx – a part of the throat – being too small, causing turbulence of the air when it moves from the nostrils, through the larynx and down to the lungs. But what causes roaring in horses, and can anything be done? Take a read below. 

The Causes of Laryngeal Neuropathy

What initially causes laryngeal neuropathy, the etiology, is often unknown (also called idiopathic). Only in 6% of cases can a cause be determined for sure. Some conditions that can cause laryngeal neuropathy include: 

• Injection of local irritative medication into the muscles of the throat. 
• Trauma to the neck or throat. 
• Infection in the guttural pouch. 

In the vast majority of cases, we simply don’t know what causes the disease. Luckily, we do know what happens afterward! 

The laryngeal nerve is a very long nerve that runs down both sides of a horse’s neck. These nerves are what control the muscles in the throat. In turn, these muscles control the arytenoid cartilage in the throat. 

The arytenoid cartilages can be pictured like two triangular pyramid-shaped structures that originate from each side of the throat and meet in the middle–like small doors of the throat.

Whenever the horse breathes in, the arytenoid cartilage will be pulled back by the muscles to allow air into the lungs.

What happens with roarer horses is that the laryngeal nerve (often the left) stops working correctly. This leads to neurogenic atrophy (deterioration) of the muscles innervated by the nerve. These muscles can then not pull back the arytenoid cartilage. Effectively part of the larynx is paralyzed and is blocking the airway. 

The reduced circumference or constriction of the throat causes air turbulence around the rima glottidis. In turn, the very characteristic roaring sound can be heard – especially when the horse is exercising.

Horses That Are Predisposed to Roaring

Any horse can develop Laryngeal Neuropathy, but recent studies suggest it is more common in tall horses simply because the laryngeal nerve is longer, which, in many ways, makes sense. The longer the nerve is, the more significant is the risk of something going wrong along the way. 

Some studies also suggest that it is more often seen in warm-blooded horses. Whether this is simply due to them generally being taller than other breeds like Islandic horses, or a predisposition due to other factors, is difficult to assess. 

Most often, the conditions present when the horse is around two to six years old. However, as it is a degenerative condition (meaning it can worsen over time), it could affect the horse before it starts displaying any symptoms. 

Diagnosing Roaring in Horses

Often a tentative diagnosis can be made based on the symptoms the owner report. Most experienced horse owners will have heard a roarer horse at some point in their life and will recognize it on their own relatively quickly. Besides the roaring or wheezing, the most common symptoms are: 

• A decreasing exercise tolerance. 
• Difficulty breathing during or after exercise. 
• Unwillingness to gallop – or stops suddenly.  

A definite diagnosis can only be made after an endoscopic examination of the larynx, preferable during exercise. This should not be done when the horse is sedated, as some sedative drugs can cause the arytenoid cartilage to lose its ability to abduct – giving a false-positive diagnosis. 

When doing an endoscopic exam of the throat and larynx, the mobility and abduction of the arytenoid cartilage will be assessed and judged on a grading scale from one to four, depending on how affected the horse is. 

On this scale, one is normal abduction and synchronized movement of the cartilage during respiration. Four are laryngeal hemiplegia (complete immobility of the arytenoid cartilage and vocal cords during inspiration). 

Available Treatment Options

Laryngeal neuropathy can be very uncomfortable for some horses, while it for others won’t matter much. What treatment option will suit a specific horse depends on several factors: 

• Use: A horse primarily used for light riding in the forest or maybe isn’t being ridden at all will have different needs compared to a competing racehorse. 
• The condition: How badly affected the horse is will have a significant impact on what treatment is necessary and valuable. 
• Economy: Surgery is expensive. Not all owners will have the capital for costly treatment and may therefore have to opt for a cheaper conservative therapy (if the veterinarian can defend this from an animal welfare point of view). 

In the end, there are currently two options when it comes to treating roaring in horses: Surgery or conservative therapy. 

Surgery 

The most common treatment option for roaring in horses is laryngoplasty surgery, also called a tie-back surgery. Sometimes in combination with a ventriculocordectomy (VCE).

With a tie-back surgery, the horse will be sedated, and an incision on the side of the throat will be made to access the crycoarythenoideus muscle. From here, a small suture will be passed through the muscle into the arytenoid cartilage, and this will then be tied together. 

Effectively ‘tying back’ the cartilage–hence the name and preventing it from abducting and obstructing the airway. 

A ventriculocordectomy is when part of the vocal cord is removed to allow even more air to pass through the area. 

The surgery is almost always a success – depending slightly on the success criteria, which can vary between countries. In most cases, the surgery is considered a success if the horse can perform like before the roaring presented and with no to minimum sound coming from the horse when it breathes. 

As with all surgeries, there are risks of complications afterward, including the risk of pneumonia and infections. They are luckily rare, though. 

The most common long-term complication afterward is lack of abduction. Over time the suture placed in the muscle and the arytenoid cartilage can soften, and the cartilage can move back and obstruct the airways. 

This is, however, not something that happens immediately and not to all horses, why it is not considered a big issue in most cases. 

Conservative Treatment 

For some horses and owners, surgery isn’t an option. This could be due to the current economy, logistics, or other practical reasons. If the obstruction isn’t too significant, some horses can live relatively comfortable lives, despite some degree of roaring. As long as a veterinarian regularly checks it to ensure it isn’t getting any worse. 

For horses that can’t be operated on, the best option is to limit strenuous exercising and perhaps only use the horse as a pleasure mount. 

What to Do if Your Horse is Roaring or Whistling

What type of treatment a specific horse needs depends on the unique needs of the owner and horse. So, if you suspect your horse is suffering from laryngeal neuropathy, consult your veterinarian. It will not go away, and in severe cases, it can be very uncomfortable for the horse. Imagine constantly not being able to breathe correctly. 

A veterinarian will confirm the suspected diagnosis and guide you towards the best treatment option for you both. 

The Outcomes and Aftercare Required

Generally speaking, roaring in horses is rarely a life or death issue – it’s a performance issue. A horse only used for walks can live an exceptionally happy and otherwise healthy life with a mild roaring case. However, if your horse is a performance horse or experiencing significant discomfort, it will need to be treated by a veterinarian.

Luckily though, most surgeries to treat roaring in horses proceeds without complications and will almost immediately afterward improve the horse’s quality of life, even more so after they’ve healed completely.

The healing does take some time, though, with at least 12 weeks of rest and then slowly increasing exercise and intensity. If you follow your veterinarian’s recommendations, the majority of horses will be able to go back to performing in competitions, as well as galloping across the field, as soon as they are appropriately restituted and healed. 

If you enjoyed this article and you are considering becoming an Equine veterinarian, you can read our article on How do you Become an Equine Vet.