Laryngeal Whistling in Horses: When the Sound Indicates Health

‍What is Laryngeal Whistling in Horses?

Laryngeal whistling in horses is a disease of the larynx, which in most cases is caused by partial paralysis of the laryngeal muscles or the supplying laryngeal nerve. A typical sign of laryngeal paralysis is a whistling sound when inhaling, which is particularly noticeable under stress.

In 90% of cases, the left side of the larynx is affected by paralysis or dysfunction. The recurrent laryngeal nerve can no longer lift the cartilage and thus no longer stretch the vocal cord behind it. This leads to a rejuvenation of the respiratory tract. As horses can only breathe through their nose, they need a fully functional larynx, which is the entrance to the windpipe. The larynx is, so to speak, the switch that opens the windpipe when breathing and closes it when swallowing. It thus prevents the horse from inhaling food and swallowing air.

If the function of the larynx is impaired, it no longer opens sufficiently to allow 100% of the inhaled air to pass into the lungs. The horse experiences breathing difficulties or even shortness of breath, and the lack of oxygen results in a drop in performance.

And why is this respiratory disease called laryngeal whistling? Although the horse's palate is very long, it is extremely narrow in relation to its body size. This means that the airflow has to overcome a certain resistance. If the larynx does not open completely, the tract becomes even narrower, the pressure is increased further and the vocal cord begins to flutter. You can imagine it like a draught in a narrow passage: The narrower the passage and the stronger the wind, the louder the wind whistles. Transferred to the horse, this means that the more air is forced through the narrowed respiratory tract, the more intense the whistling becomes - this can be heard above all at a trot or canter, when the respiratory rate and oxygen demand are at their highest.

Other names for laryngeal whistling are vocal cord paralysis or laryngeal paralysis, which describes the cause very well. Names such as tone in horses or the English form roarer, on the other hand, describe the typical symptoms of the disease.

Large horse breeds such as warmbloods, thoroughbreds or some cold-blooded breeds are often affected. Among thoroughbreds, between 3 and 8% are affected by laryngeal whistling.

Watch the following video from the ClipMyHorse.TV Academy to find out what laryngeal whistling is and what a day in the surgery to treat laryngeal whistling is like:

Symptoms of Laryngeal Paralysis

The unnatural sound under stress is probably the most prominent symptom of laryngeal whistling. Depending on the type of laryngeal disease, the sound can be a whistling, grunting, humming or roaring. However, the most common disorder is laryngeal paralysis, which tends to be accompanied by a whistling sound, which is where the disorder gets its name. It has also been shown that the horse's head and neck posture has an influence on the intensity of the breathing noise: a bent neck, a horse walking close to the reins or one that is tied up makes the symptoms more pronounced.

Other symptoms of laryngeal whistling are:

• Shortness of breath
• reluctance to move or panic because the horse cannot breathe under stress
• Weak performance and loss of performance due to lack of oxygen
• Loss of rhythm in canter: The horse breathes in with every canter jump. If there is a breathing disorder, the rhythm is also lost.
• Soft, hoarse-sounding whinnying
• Respiratory distress and suffocation if the cartilage is sucked in and completely closes the windpipe

Laryngeal whistling can vary in severity from horse to horse. It is therefore divided into five grades ranging from mild symptoms to severe breathing difficulties. In grades 1 and 2, laryngeal paralysis has no effect on the horse. In grades 3 and 4, the vocal cord has already visibly and permanently changed. At the highest grade, the vocal cord is completely paralyzed and surgery is unavoidable.

If the sound in the horse only occurs under heavy strain, the horse can continue to be used as a lightly working leisure horse. However, a veterinary examination and care at regular intervals is more than advisable, as the symptoms can worsen over time.

Causes of Laryngeal Whistling

There are several theories and theories about the exact causes of laryngeal whistling, but so far none of them have been scientifically proven. The verdict is usually unspecific origin or idiopathic.

Why the laryngeal nerve, and preferably the left base, is responsible for the hemiplegia of the larynx can possibly be explained by its length and proximity to the pulsating aorta. Another assumption is an overstretching in the womb or a genetic disposition.

Another theory could be a peripheral venous injection, when the medication is injected into the vein and thus irritates the laryngeal nerve. Experts suspect this to be the cause, especially if the right laryngeal nerve and therefore the right side of the larynx is paralyzed.

Even if the exact cause of laryngeal whistling cannot be clearly defined, there are a number of factors that can contribute to laryngeal whistling:

• Injuries to the larynx
• Air sac mycosis
• Complications during general anesthesia, e.g. due to hyperextension of the neck if the horse is lying in an unfavorable position
• Tumors
• Abscesses 
• Poisoning
• Rarer: Druse or fungal infections
• Narrow riding style (roll cure)
• Throat strap too tight

Horses are designed to escape quickly and therefore need plenty of oxygen when training or working. A clear air supply is crucial for effective breathing and an excellent supply of oxygen to the muscles. This supports a healthy immune system, high performance and the well-being of the horse. However, contaminants such as dust, dirt or allergens can clog or irritate the airways, making breathing difficult. You can find out how to protect and support your horse's lungs in this video in the ClipMyHorse.TV Academy:

‍The Sound in the Horse: Consequences of Laryngeal Whistling

The consequences of laryngeal whistling are obvious: the horse quickly runs out of breath during work and its performance is massively reduced. In the worst case, however, the horse can also suffocate if the larynx collapses completely. Swallowing can also be a danger with laryngeal whistling if the larynx no longer closes completely when swallowing. This is particularly the case after laryngeal surgery (see treatment of laryngeal whistling).

Until 2002, laryngeal whistling was still considered a warranty defect and allowed the horse to be returned to the breeder. Today, however, there are good chances for laryngeal whistlers thanks to various surgical procedures.

Diagnosis of Laryngeal Whistling

Even if the whistling on inhalation clearly indicates laryngeal whistling, the diagnosis should always be made by a veterinarian. This begins with a clinical examination by listening. Depending on the severity of the disease, the vet may be able to feel the muscle atrophy by external palpation. An endoscopy of the larynx finally confirms the diagnosis.

This can initially be carried out at rest. A flexible, thin tube with a camera is inserted through the nose to the larynx. A dynamic endoscopy can also be carried out on a treadmill or on horseback in order to determine the characteristics of the horse's sound under stress. 

How Do You Treat Laryngeal Paralysis in Horses?

In order to improve the quality of breathing, there is hardly any way around an operation for laryngeal whistling. Depending on the severity of the disease, the type of Roarer operation is selected accordingly. There is the option of laryngoplasty, ventriculocordectomy and nerve transplantation. All surgical procedures are performed under general anesthesia, but depending on the horse's temperament, some can also be performed under sedation in a standing position.

In laryngoplasty, also known as tie-back surgery, one or two non-absorbable, tension-resistant sutures are implanted in the horse's larynx to stretch open the dysfunctional half of the larynx. The trick here is not to open the vocal cord too far so that the right half of the larynx can reach the open left half when swallowing and the larynx can still close. Laryngoplasty is generally very effective as it restores the airflow. However, there is a risk that the left side will be stretched too tightly and a permanently open cartilage can lead to swallowing disorders, choking and coughing.

Ventriculocordectomy is less effective in terms of restoring airflow, but less risky. This can be performed on a sedated horse without the risk of general anesthesia. Lasers are used to scar the vocal cords, which leads to a tightening of the tissue. Depending on the severity, the vet may also decide to remove the vocal sac and vocal fold of the larynx. This is then performed under general anesthesia.

A future-oriented treatment method for laryngeal whistling is nerve transplantation. Under general anesthesia, a healthy nerve is removed from surrounding tissue and connected to the damaged laryngeal nerve or replaces it. The aim is to restore the natural stability of the laryngeal tissue in this way. Another positive aspect of nerve transplantation is that there are very few post-operative complications. It is particularly suitable for horses that are in the early stages of laryngeal whistling before the larynx collapses completely.

The costs for a laryngectomy vary from clinic to clinic, as care, accommodation and length of stay must of course be taken into account. Nevertheless, you can expect to pay several thousand euros for a l aryngectomy.

After a laryngeal pipe operation, you should allow two to three months for the surgical wound and the larynx to heal. After three weeks, you can slowly start walking again, but cantering can only be resumed after at least eight weeks or longer.

Frequently Asked Questions About Laryngeal Whistling in Horses

Can laryngeal whistling be prevented?

No, laryngeal whistling cannot be prevented, as scientists disagree on the exact causes. Therefore, there are no avoidable clues to prevent laryngeal whistling. However, it is suspected that genetics could be involved in the sound. Every rider can also pay attention to an appropriate riding style and natural contact to prevent physical damage to the larynx through squeezing or displacement of the palate.

Good to know: Performance diagnostics make it possible to assess and optimize the fitness level of a horse, regardless of whether it is a leisure partner or an athlete. These diagnostics make it possible to identify existing performance deficits and develop a customized training plan to improve the horse's performance. This is particularly important for horses with conditions such as asthma, headshaking, osteoarthritis, laryngeal whistling or heart problems, as a stress test helps to determine when exercise becomes problematic. You can find out how you can optimize your training thanks to performance diagnostics in the ClipMyHorse.TV Academy in the following video:

‍What Does Laryngeal Whistling Sound like in Horses?

Laryngeal paralysis causes unnatural breathing noises that can sound like whistling, snoring, growling, grunting, roaring or rattling. The type of sound says something about the origin of the sound in the horse. Laryngeal whistling is the generally known term, but it is not always a paralysis of the recurrent laryngeal nerve:

A deep, short rattle is more likely to be due to laryngeal paralysis, while a high, shrill whistle when inhaling is caused by a blockage in the throat. A low-pitched growl can be caused by an injury to the nose and if the horse grunts when breathing, the palate may have been injured.

How Much Does a Sound Operation on a Horse Cost?

It is not possible to give a general price range for a laryngectomy, as the costs vary between clinics and federal states. The chosen surgical technique also plays a role in the pricing. However, you should expect to pay several thousand euros for a sounding operation on a horse.

Is Laryngeal Whistling Bad for Horses?

Laryngeal whistling in horses should always be treated by a vet. Even mild symptoms can worsen over time and literally take the horse's breath away. Horses are flight animals whose airways are designed in such a way that they can only breathe easily when they are fully functional. Horses only breathe in and out through their nose. If the upper respiratory tract is damaged or restricted, the horse cannot open its mouth to get the oxygen it needs. In the worst (untreated) case, laryngeal paralysis ends with the horse suffocating.

Can Laryngeal Whistling Get Worse?

In fact, the symptoms of laryngeal whistling in horses can worsen over time. This is because laryngeal paralysis is a progressive disease in which even young horses can show the first symptoms. If a horse has a laryngeal disorder of the lower grades, this can also worsen over time. Furthermore, a dysfunctional larynx can lead to other respiratory diseases such as coughing or swallowing disorders. For this reason, a vet should be consulted at the slightest suspicion of sound in the horse and a diagnosis should be made with an endoscopy of the larynx.