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Roarers


“Roarers” are horses that make unusually loud noise as their breathing becomes faster and deeper with increasing exercise. Roaring is caused when one or both arytenoid cartilages in the throat become paralyzed and partially block the airway instead of being automatically retracted as the horse breathes.


According to Bryan Waldridge, D.V.M., staff veterinarian for Kentucky Equine Research, this paralysis is more common on the left side of the horse’s throat and is termed left-sided laryngeal hemiplegia. Treatment of the condition involves tie-back surgery in which the cartilage is pulled to the side and sutured to keep it from interfering with the flow of air. In some horses, the vocal cords are also removed (ventriculocordectomy) to increase airflow and reduce noise as the horse breathes.







Various types of material including standard sutures and plastic cable ties have been used to secure the cartilage, with varied success in keeping the tissue in place after the surgery. Lycra sutures, which have more elasticity than rigid ties, have been used with good results in some horses. A report published in Equine Veterinary Journal indicated that Thoroughbred racehorses have a good prognosis for racing when Lycra sutures are used in tie-back procedures, with post-surgery increases in both performance index and Beyer Speed Figures. Use of Lycra sutures led to a lower surgical failure rate and fewer postoperative complications than when other materials were used in the procedure.

Signs & symptoms of a roarer


•Usually seen in horses between 3–7 years old
•Exercise intolerance that has gotten worse over weeks to months
•Classic “whistling” or “roaring” noise heard during exercise (usually while cantering or higher activity)
•Sound of the horse’s whinny may change
•Gasping for breath after exercise
•Veterinarians may note muscle atrophy (or shrinking) at the throat latch area


Diagnosing a roarer

Laryngeal hemiplegia is a graded on a scale of 1–4, with 4 being complete paralysis of the cartilage. Standing endoscopy can diagnose cases that are grade 3–4 and some cases that are grade 2. High-speed treadmill endoscopy or over ground dynamic respiratory examination may be necessary to diagnose cases that are questionable on standing endoscopy and can be used to ensure that no other concurrent upper airway problems are contributing to the exercise intolerance or respiratory noise. Additionally, laryngeal ultrasound can be used to evaluate the density of laryngeal muscle fibers to determine if they are correctly innervated. 






 

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