Arytenoid chondritis in the horse is a progressive, inflammatory condition of the arytenoid cartilages that is thought to develop after ulceration or penetration of the mucosal surface of the arytenoid cartilage. It is commonly unilateral but may also present as a bilateral condition. Local bacterial invasion leads to infection, heat, and hyperemia of the surrounding cartilage, which is quite painful and may lead to some degree of laryngeal paresis. If left untreated, the horse can develop excessive granulation tissue that projects into the tracheal lumen and may cause partial obstruction. This can cause an inspiratory and expiratory stridor. If infection extends into the body of the cartilage, it can cause deformation of the cartilage, reduced airflow, and exercise intolerance. Coughing may be a feature at any stage of the disease.
Diagnosis is primarily made with upper airway endoscopy, although calcification of the cartilage may be seen in chronic cases using radiography, and ultrasonographic features have been described. In young Thoroughbreds, a diagnosis of arytenoid chondritis is often made around sales time. These cases are often mild, acute, and not associated with clinical signs. Some care should be taken to look for a kissing lesion on the contralateral arytenoid.
The condition will often respond to broad-spectrum antibiotic treatment, which is often administered parenterally, followed by multiple weeks of potentiated sulfonamide medication orally. Some clinicians will also use a daily throat spray of antibiotics and/or anti-inflammatory agents delivered through a nasopharyngeal catheter. Response to treatment is monitored endoscopically and stopped when the lesions have resolved. The prognosis for complete resolution is generally good.
In horses with excessive granulation tissue production, surgical resection of the granulation tissue can be achieved either using a nasal snare or a laser through an endoscope. If lesions are larger or less accessible, surgical resection can be performed through a laryngotomy in the standing or anesthetized horse. In severe cases with cartilage deformation or lack of response to other approaches to treatment, a partial arytenoidectomy may be required. However, the prognosis for racing after arytenoidectomy is guarded and related to the severity of the condition, and it may only offer a way to salvage the horse for less athletic endeavors.