What is Roaring?
Roaring in horses, otherwise known as laryngeal hemiplegia, is a respiratory disease that has a negative effect on a horse’s upper airway. The larynx is like a bridge between the nasal passage in the trachea (windpipe). It contains cartilage that lets air flow into the trachea while protecting the horse’s airway when he swallows. When a cartilage, or more than one cartilage, suffers a lack of nerve stimulation (innervation), the throat then becomes paralyzed or severely weakened. The horse may exhibit noticeable raspy sounds or wheezing. This typically occurs during exercise or any type of strenuous activity. Furthermore, the decrease in the airflow into the lungs may also cause your horse to resist any exercise.
The cartilages that are affected by roaring are the arytenoids. The arytenoid cartilages are responsible for the air flowing into the windpipe, and they open to allow the air in. When roaring occurs, these cartilages do not open properly, thus significantly decreasing the amount of air which needs to flow into the lungs. Roaring in horses is not a life-threatening disease and there are treatment options which are obtainable to keep your horse performing.
Roaring in horses is a condition in which the upper airway ceases to work properly, thus lacking in the amount of flowing air into the lungs. This results in a wheezing or abnormal whinny from the horse during and after physical activity.
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Symptoms of Roaring in Horses
If your horse is showing symptoms of roaring, make an appointment with your veterinarian. Symptoms of roaring commonly occur between the ages of three and seven years. Symptoms can include:
- Resistance to exercise
- Whistling during activity or canter
- Roaring or wheezing sound made during physical activity
- Difficulty breathing after physical activity
- A change in sound of the horse’s whinny
Although laryngeal hemiplegia can affect any breed or type of horse, it seems to affect performance horses more often. Types of horses commonly affected by roaring are:
- Draft Horses
- Racing Thoroughbreds
- Quarter Horses
- Males, taller than 15 hands
Causes of Roaring in Horses
Causes of laryngeal hemiplegia, or roaring, include the shrinking (atrophy) of the muscles within the larynx. Causes include:
- Trauma (if on the right side)
- Nerve damage
- Lack of nerve signals for arytenoids to function properly
- Lack of air flow to the lungs
Diagnosis of Roaring in Horses
If your horse is exhibiting any of the above symptoms, make an appointment with your veterinarian. Your veterinarian will carefully perform a physical examination, asking questions about his symptoms, the severity of the symptoms, and when they occur. He may perform bloodwork, a biochemistry profile, and any other preliminary laboratory testing.
He will carefully listen to your horse in order to investigate the way he is breathing and to hear any abnormal sounds. After listening to your horse, your veterinarian may perform an examination of your horse’s respiratory system. This is typically done by using an endoscopic procedure to rule out any other conditions that may be contributing to your horse’s breathing difficulties. This is performed by placing a thin, flexible tool in and through the nose, and inside the pharynx. This method is highly effective in looking for abnormalities in the larynx as the horse is breathing. Typically, the left side is affected in laryngeal hemiplegia. This test may also be performed as the horse is walking on a treadmill in order to have an increased activity to get accurate results.
There is also another procedure which is very similar to this without having the horse walk on a treadmill. This method is known as an overground endoscopic procedure. This test uses a camera which is placed near the horse’s nose and connected to the bridal. There is also a transmitter that is placed on the back of the rider which sends a signal to an electronic monitor. This shows the larynx’s activity as the horse is performing normal physical activity. If this method is available, your veterinarian may suggest this type of diagnostic tool.
If your horse is diagnosed with roaring in horses, your veterinarian will explain the level, or “grade”, of his condition. He will then explain the various treatment options that are available.
Treatment of Roaring in Horses
Treatment will depend on your horse’s condition. There are a variety of treatment methods for this condition which include:
Prosthetic laryngoplasty is a very common method of treatment. The veterinarian will place your horse under general anesthesia and “tie back” the paralyzed, abnormal-working cartilage. The cartilage is placed through an incision in the throat.
Cordectomy, otherwise known as ventriculectomy, is a method performed by removing the vocal cord and the ventricle, which is underneath the affected cartilage (arytenoid). This results in a more open and wider airway. Your horse will be placed under general anesthesia for this procedure, and an incision is placed underneath the jaw and into the horse’s airway. A laser procedure may be used instead, which is placed up into the nostril.
Another surgical procedure, an arytenoidectomy, is performed to remove the affected arytenoid. This results in a larger, wider opening into the trachea. An incision is placed into the throat as your horse is under general anesthesia. This surgical procedure has more risks than others; it is usually performed when other surgical methods are not successful.
Neuromuscular Pedicle Graft
This surgical procedure has a goal of restoring the nerves within the paralyzed cartilage. This is performed by removing a nerve from a neck muscle and placing it within the muscle that controls the affected cartilage. This is known as innervation, and generally takes several months, and sometimes close to a year, in order for the nerves to begin working again.
Recovery of Roaring in Horses
Depending on the type of surgical procedure, your horse will have varying methods of recovery. Your veterinarian will explain to you in full detail how to care for your horse. He will also need to see your horse again to remove any sutures or staples.
It will be recommended that your horse rest in his stall for a time set forth by your veterinarian. He will explain when you may allow your horse to resume activity. Your companion may be placed on prescription antibiotics, throat sprays, and anti-inflammatory medications. All of his aftercare will be dependent on the type of procedure and how well he is progressing toward recovery.
Prognosis is typically good, but this will depend on the severity of your horse’s roaring. Active horses or performance horses do have a prognosis of fair to good in terms of returning to normal activity if they respond well to the treatment.
Roaring Questions and Advice from Veterinary Professionals
When my horse is roaring but doesn't show signs of exercise intolerance, is she still okay to continue regular work? The roaring is there and she takes about 1-2 min to return to normal breathing after strenuous work.
Exercise intolerance is a symptom of laryngeal hemiplegia but not seen in every case. Roaring is normally caused by the arytenoid cartilage not functioning normally. A crude test is called a ‘slap test’ where you hold the larynx in one hand and slap the thorax with the other; you should feel the larynx move (don’t try if you’re not familiar with this test, most horse owners are). I would recommend calling out your Veterinarian as airway narrowing from inflammation, polyps, tumours and foreign bodies may cause audible noise as well. Regards Dr Callum Turner DVM
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