Roaring in Horses - Laryngeal Hemiplegia

What is Laryngeal Hemiplegia (Roaring) in Horses?

Laryngeal hemiplegia, commonly known as roaring, is a disorder of the horse’s larynx, usually caused by a partial paralysis of the laryngeal muscles or the nerve that controls them. A classic sign of this condition is a whistling or roaring noise during inhalation, especially under exertion.

In 90% of cases, the left side of the larynx is affected by paralysis or dysfunction. When the recurrent laryngeal nerve fails to activate the arytenoid cartilage, the corresponding vocal cord can no longer fully tense. This narrows the airway, affecting the horse’s breathing. Horses can only breathe through their noses, which makes a fully functional larynx essential. The larynx acts as a gateway to the trachea, ensuring proper airflow when breathing and closing to prevent food from entering the airway during swallowing.

If the larynx does not function properly, it does not open wide enough to allow adequate airflow into the lungs. This results in breathing difficulties or even respiratory distress, leading to oxygen deprivation and reduced performance.

Symptoms of Laryngeal Hemiplegia in Horses

The most distinctive symptom of roaring is an abnormal breathing noise during exertion. Depending on the severity, the sound may resemble whistling, grunting, humming, or roaring.

The most common form is laryngeal paralysis, which is typically associated with a whistling tone – hence the term roaring.

Another factor influencing the intensity of the noise is the horse’s head and neck position:

• A flexed neck, tight rein connection, or restricted movement can exacerbate symptoms.

Other symptoms of roaring include:

• Shortness of breath
• Lack of motivation to move, sometimes even panic due to difficulty breathing under exertion
• Weakness and performance decline due to oxygen deficiency
• Irregular canter rhythm, as horses inhale with each canter stride – a breathing disorder leads to rhythm loss
• Weak, hoarse neighing
• Severe cases: respiratory distress and risk of suffocation if the arytenoid cartilage collapses into the airway

Roaring is classified into five severity grades, which help determine the need for treatment and whether the horse can continue working.

• Grade 1–2: Mild roaring, little to no effect on breathing and performance.
• Grade 3–4: Advanced laryngeal paralysis with noticeable changes in the vocal cords, increased breathing noise, and reduced performance.
• Grade 5: Severe roaring, complete paralysis of the vocal cords, requiring surgical intervention.

If the whistling noise only occurs under heavy exertion, the horse can often still be used as a leisure horse. However, regular veterinary check-ups are necessary, as symptoms may worsen over time.

Causes of roaring in horses

The exact causes of roaring are not fully understood. In many cases, the condition remains idiopathic, meaning no clear cause can be identified.

One widely discussed theory is damage or degeneration of the laryngeal nerve, particularly on the left side.

Possible contributing factors:

• Laryngeal injuries
• Guttural pouch mycosis
• Complications from general anesthesia, especially due to excessive neck extension
• Tumors or abscesses in the laryngeal region
• Poisoning
• Infections such as strangles or fungal infections (very rare)

Training and tack may also play a role:

• Excessive head flexion (rollkur)
• A too-tight throatlatch that mechanically restricts the larynx

Another potential trigger is nerve irritation from injections, particularly if medication accidentally enters a vein, damaging the recurrent laryngeal nerve.

Since symptoms can gradually worsen, early diagnosis and veterinary monitoring are crucial for effective treatment.

How is Laryngeal Hemiplegia Diagnosed?

Even though a whistling noise during inhalation is a strong indicator of roaring, a definitive diagnosis must be made by a veterinarian.

Clinical Examination

The veterinarian will begin with a clinical examination, which includes:

• Listening to the horse’s breathing for irregularities
• Palpating the larynx to check for muscle loss or structural changes

Endoscopy of the Larynx

To confirm the diagnosis, an endoscopy is performed. A flexible tube with a camera is inserted through the horse’s nose to examine the larynx.

Types of endoscopy:

• Resting endoscopy: Performed while the horse is standing still to assess structural changes.
• Dynamic endoscopy: Conducted while the horse is moving (on a treadmill or under saddle) to evaluate how the larynx functions under exertion.

An early diagnosis is crucial to determining the severity of roaring and choosing the best treatment.

Roaring in horses treatment

Surgical intervention is usually the only way to significantly improve breathing. The chosen method depends on the severity of the condition.

Roaring surgery in horses

Surgery is often the only effective treatment for horses with severe laryngeal hemiplegia (roaring). The choice of surgery depends on the severity of the condition, the horse’s intended use, and the expected outcome. Below are the most common surgical procedures used to treat roaring in horses.

Frequently Asked Questions About Roaring in Horses

What is laryngeal hemiplegia?

Roaring is a disorder caused by partial paralysis of the laryngeal muscles or nerves. This prevents the larynx from fully opening, restricting airflow.

How can you recognize roaring in horses?

A characteristic sign is a whistling or roaring sound during inhalation, particularly under exertion. Other symptoms include shortness of breath, reduced performance, reluctance to move, and, in severe cases, respiratory distress.

How dangerous is roaring in horses?

In mild cases, the condition has little to no impact on the horse. However, in more severe cases, it can cause significant breathing difficulties and performance loss. In extreme cases, the larynx may collapse to the point where the horse cannot get enough air.

Can you ride a horse with roaring?

This depends on the severity of the condition:

• Mild roaring (Grade 1–2): Riding is generally not a problem.
• Moderate cases (Grade 3–4): Some exercise limitations may occur, especially in higher gaits like the canter.
• Severe cases (Grade 5): These horses should not be used for sports as they may suffer from breathing difficulties and a risk of suffocation.

How is roaring diagnosed?

A veterinarian will perform a clinical examination, listening to the horse's breathing. To confirm the diagnosis and determine the severity, an endoscopy of the larynx is performed.

What does it mean when a horse is roaring?

Roaring refers to the abnormal breathing noise caused by restricted airflow due to laryngeal hemiplegia. It occurs primarily during exertion and is a sign of laryngeal dysfunction.

How to treat roaring in horses?

The most effective treatment is surgical intervention, such as tie-back surgery (laryngoplasty) or vocal cord removal (ventriculocordectomy). Some mild cases can be managed with adjusted exercise and monitoring.

How much does horse roaring surgery cost?

The cost varies depending on the clinic and procedure. The average prices range between $3,000 and $5,500.

• Laryngoplasty (Tie-Back Surgery): $3,000 – $4,500
• Ventriculocordectomy (Vocal Cord Removal): $2,000 – $3,500
• Nerve Transplant Surgery: $4,000 – $5,500

What is tie-back surgery on a horse?

Tie-back surgery (laryngoplasty) is a procedure where the paralyzed cartilage in the larynx is sutured open to improve airflow and reduce breathing difficulties.

What is the recovery time for a horse tie-back surgery?

Recovery typically takes 6–8 weeks, with restricted exercise during the healing process.

Is roaring in horses hereditary?

There is some evidence suggesting that roaring may have a genetic component, particularly in Thoroughbreds. However, a definitive scientific confirmation is still pending.

Can acupuncture help treat roaring in horses?

Acupuncture may be used as a supportive therapy in mild cases, but it does not replace medical treatment or surgery.

Should you buy a horse with roaring?

It depends on the severity of the condition and the intended use of the horse:

• Mild cases (Grade 1–2): Usually no issue for leisure riding.
• Moderate cases (Grade 3–4): Veterinary assessment is recommended before purchase.
• Severe cases (Grade 5): These horses are not suitable for sports and may require surgery.

Can roaring in horses be prevented?

No, roaring cannot be prevented, as its exact causes remain unclear. However, genetics may play a role. Riders should maintain correct head and neck positioning to avoid mechanical damage to the larynx.

How does roaring sound in horses?

Laryngeal paralysis causes unnatural breathing noises, which can be whistling, snoring, humming, grunting, roaring, or wheezing. The type of sound can indicate the origin of the issue:

• A deep, short wheeze is often linked to laryngeal paralysis.
• A high-pitched whistle on inhalation may indicate throat obstruction.
• A deep humming may result from a nasal injury.
• A grunting sound can indicate palate damage.

Is roaring in horses serious?

Roaring should always be examined by a veterinarian. Even mild symptoms can worsen over time, severely affecting the horse's breathing. Horses rely entirely on nasal breathing and cannot compensate for airway restrictions by breathing through the mouth. In the worst-case scenario, untreated laryngeal paralysis can lead to suffocation.

Can roaring get worse over time?

Yes, roaring is a progressive condition. Even young horses may show early symptoms that deteriorate over time. A dysfunctional larynx can also lead to other respiratory issues, such as coughing or swallowing disorders. Early veterinary diagnosis and endoscopic examination are essential for treatment.