Laryngeal hemiplegia in the horse : an update

Laryngeal hemiplegia is a progressive upper airway dysfunction in the horse. It is not only seen in thoroughbred racehorses but also in warmblood horses, draft horses and in potties. The condition is most frequently seen on the left side. The left laryngeal recurrent nerve gradually loses function and the function of the left cricoarythenoideus dorsalis muscle is compromised. This condition is most often idiopathic. It possibly leads to exercise intolerance but a respiratory noise is often the primary complaint of the owner. Right sided laryngeal hemiplegia is almost always related to other pathologies causing the nerve to malfunction. The diagnosis is not always easy because of the restricted availability of endoscopy in the field. A better understanding of laryngeal ultrasound examination might offer a new possibility in diagnosing laryngeal hemiplegia. If abnormal inspiratory sound is the only problem, laser treatment alone can be satisfactory. If the horse shows clear signs of exercise intolerance, further treatment is needed. If correctly executed, the outcome of laryngoplasty is good. Other techniques, like nerve grafting and pacemakers, are being explored and might even be regarded as better alternative treatments in the future, as these are more physiologic compared to laryngoplasty. In sporthorses presented with idiopathic laryngeal neuropathy without postoperative complications, the prognosis is good.