Laryngeal Hemiplegia in Horses: Roaring, Noise, and Surgery Options
- Laryngeal hemiplegia, also called recurrent laryngeal neuropathy or "roaring," happens when one side of the larynx cannot open normally during breathing, most often the left side.
- Common signs are an inspiratory whistle or roar during exercise, reduced stamina, and poor performance, especially at faster work.
- Diagnosis usually requires endoscopy. Some horses need dynamic or overground endoscopy because the airway can look different during exercise than it does at rest.
- Treatment depends on your horse's job, severity, and goals. Options may include workload changes, ventriculocordectomy, prosthetic laryngoplasty (tie-back), or selected reinnervation procedures in younger horses.
- Typical 2025-2026 US cost range is about $600-$1,500 for workup alone and roughly $1,500-$6,500+ if surgery and hospitalization are needed.
What Is Laryngeal Hemiplegia in Horses?
Laryngeal hemiplegia is a disorder of the upper airway in which one side of the larynx does not open normally during inhalation. In horses, this is usually the left side and is commonly linked to recurrent laryngeal neuropathy, meaning the nerve that controls the main airway-opening muscle is not working well. As that muscle weakens and shrinks, the arytenoid cartilage and vocal fold can collapse inward during exercise.
That collapse narrows the airway. Pet parents and trainers often notice a high-pitched whistle, a harsher "roar," or a horse that seems to tire sooner than expected. Some horses mainly have noise, while others have a meaningful drop in airflow and athletic performance.
This condition is especially important in performance horses because the problem becomes more obvious when oxygen demand rises. A horse may sound normal at rest, then become noisy or short-winded at speed. Even after treatment, the airway usually improves rather than returning fully to normal, so your vet will help match expectations to your horse's intended use.
Symptoms of Laryngeal Hemiplegia in Horses
- Inspiratory whistle or roaring noise during exercise, especially at faster gaits
- Reduced stamina or exercise intolerance
- Poor performance compared with prior fitness or training level
- Needing to slow down, stop, or recover longer after work
- Noise that worsens with intensity, collection, or racing speed
- Occasional coughing or feed material at the nostrils after surgery complications, if a tie-back has already been performed
- Rarely, obvious breathing effort at rest in severe or complicated cases
Many horses with laryngeal hemiplegia look comfortable in the barn and only show signs under saddle, on the track, or during hard work. A new inspiratory noise plus fading performance is a strong reason to schedule an exam with your vet.
See your vet immediately if your horse has breathing difficulty at rest, marked distress after exercise, fever or coughing after recent airway surgery, or sudden worsening of noise and performance. Those signs can point to a more urgent airway problem or a post-operative complication.
What Causes Laryngeal Hemiplegia in Horses?
The most common cause is recurrent laryngeal neuropathy (RLN), a progressive problem affecting the recurrent laryngeal nerve. This nerve controls the cricoarytenoideus dorsalis muscle, which is the main muscle that opens the airway. When the nerve fails, the muscle weakens and the arytenoid cartilage cannot stay abducted during inspiration.
In many horses, especially taller breeds, the exact trigger is not fully defined and likely has a heritable component. Thoroughbreds and draft breeds are overrepresented, and left-sided disease is far more common than right-sided disease. Larger body size and long nerve length are thought to contribute.
Less common causes include direct trauma to the nerve, guttural pouch disease, complications from injections near the neck vessels, and certain toxic plant or chemical exposures. Your vet may also consider other upper airway disorders that can mimic roaring, because more than one dynamic airway issue can occur in the same horse.
How Is Laryngeal Hemiplegia in Horses Diagnosed?
Diagnosis starts with a history and physical exam focused on when the noise happens, how the horse performs, and whether the problem is stable or getting worse. Your vet may listen to the airway after exercise and review videos from training or competition, since the sound pattern can be very helpful.
The key test is endoscopy of the upper airway. A resting endoscopic exam lets your vet look at arytenoid movement and grade the degree of dysfunction. If the findings are mild or unclear, or if the horse only has trouble during work, your vet may recommend dynamic endoscopy during exercise. This can be done on a treadmill or overground and is often the best way to confirm dynamic collapse.
Additional testing may be recommended to rule out overlapping airway problems or to plan surgery. That can include bloodwork before anesthesia, imaging in selected cases, and a discussion of the horse's discipline, speed demands, and future goals. The diagnosis matters, but so does matching the treatment plan to what your horse actually needs to do.
Treatment Options for Laryngeal Hemiplegia in Horses
Spectrum of Care means you have options. Here are treatment tiers at different price points.
Budget-Conscious Care
- Exam and upper airway endoscopy at rest
- Training or workload adjustment based on intended use
- Monitoring for progression with repeat exams or video review
- Medical planning for concurrent airway issues if present
- Referral discussion before committing to surgery
Recommended Standard Treatment
- Referral-level airway workup with resting endoscopy and, when needed, dynamic endoscopy
- Prosthetic laryngoplasty (tie-back) to hold the arytenoid partially open
- Often combined ventriculocordectomy or ventriculectomy to reduce noise and improve airflow
- General anesthesia or standing approach depending on surgeon preference and case selection
- Hospitalization, discharge medications, and recheck planning
Advanced / Critical Care
- Comprehensive referral evaluation with dynamic overground endoscopy and surgical planning
- Laryngoplasty revision, partial arytenoidectomy, or other salvage procedures for failed or complicated prior surgery
- Laryngeal reinnervation in selected younger horses with partial paralysis
- Extended hospitalization, advanced anesthesia support, and intensive post-operative monitoring
- Management of aspiration, infection, or concurrent upper airway disease
Cost estimates as of 2026-03. Actual costs vary by location, clinic, and individual case.
Questions to Ask Your Vet About Laryngeal Hemiplegia in Horses
Bring these questions to your vet appointment to get the most out of your visit.
- How severe is my horse's laryngeal dysfunction on endoscopy, and does it match the signs I am seeing under saddle or in training?
- Does my horse need dynamic or overground endoscopy, or is the resting exam enough to make a treatment plan?
- Are there any other upper airway problems that could be contributing to the noise or poor performance?
- Based on my horse's job, is conservative care reasonable, or is surgery more likely to help?
- If surgery is recommended, would you suggest tie-back alone or tie-back plus ventriculocordectomy, and why?
- What is the expected recovery timeline before my horse can return to work, training, or competition?
- What complications should I watch for after surgery, especially coughing, fever, nasal discharge, or trouble eating?
- What is the full expected cost range, including diagnostics, anesthesia, hospitalization, medications, and rechecks?
How to Prevent Laryngeal Hemiplegia in Horses
There is no guaranteed way to prevent recurrent laryngeal neuropathy, especially when a horse has breed or body-size risk factors. Because the condition is often progressive and may have a heritable component, prevention is more about early recognition and thoughtful management than a single protective step.
Prompt evaluation of new exercise noise or unexplained performance decline can help your vet identify the problem before training plans or competition goals are heavily affected. Avoiding unnecessary trauma to the neck region and carefully managing guttural pouch disease or other nearby conditions may also reduce the chance of secondary nerve injury in some horses.
For breeding decisions, it is reasonable to discuss family history and airway performance with your vet, particularly in lines where roaring is common. Regular conditioning, realistic workload expectations, and early referral for airway endoscopy when signs appear can help pet parents make timely, practical choices.