Arytenoid chondropathy refers to pathologic enlargement of one or both bilateral arytenoid cartilages resulting in poor performance, respiratory noise, and respiratory obstruction.
Etiology and Pathogenesis of Arytenoid Chondropathy in Horses
The etiology is unknown; however, injury to the overlying mucosa is thought to a possible point of entry for bacterial inoculation of the arytenoid cartilage. Due to marked inflammation and infection, the arytenoid cartilage becomes deformed and is unable to abduct, compromising airflow.
Clinical Findings and Diagnosis of Arytenoid Chondropathy in Horses
Clinical signs are similar to those described for recurrent laryngeal neuropathy and include poor performance or exercise intolerance, respiratory noise, and eventual respiratory obstruction. Horses who are not in regular work may not present until dyspnea is apparent at rest.
The diagnosis is made based on endoscopic observation of an enlarged and/or misshapen arytenoid cartilage that has little to no movement. Presence of granulation tissue along the axial border of the corniculate process of the arytenoid cartilage may be present. Ulceration of the opposing arytenoid cartilage (aka “kissing lesion”) may also be present. Marked edema of the tissues adjacent to the larynx is common.
Although chondritis may be confused with laryngeal hemiplegia, misdiagnosis can be avoided by observation of the shape and size of the arytenoid cartilages. In arytenoid chondritis, the arytenoids thicken and lose their characteristic shape. Abduction and adduction are usually limited. The axial (medial) surface of the arytenoid cartilage may be distorted with granulation tissue protruding through the mucosa, and a contact (kissing) lesion may be present on the contralateral arytenoid cartilage. Arytenoid chondritis should always be considered if the right arytenoid is abnormal, as laryngeal hemiplegia is extremely rare on the right side.
In cases of arytenoid chondropathy examined early in the disease process, the endoscopic appearance may be very similar to recurrent laryngeal neuropathy. In these cases, ultrasound may be useful to help evaluate structural and compositional changes of the arytenoid cartilage itself, associated with arytenoid chondropathy. Thickening or distortion of the border of the arytenoid cartilage along with abnormal echogenicity are associated with arytenoid chondropathy. Gas within the perilaryngeal tissues may also be present.
Treatment of Arytenoid Chondropathy in Horses
Arytenoid debridement +/- drainage
Horses that present for acute chondritis require immediate resolution of inflammation (NSAIDs and/or steroids, systemic or topical via throat sprays) and infection, requiring broad-spectrum antimicrobial coverage. Horses that present in acute, respiratory dyspnea or distress may require placement of a temporary tracheotomy. Treatment is continued until improvement is visible endoscopically and dyspnea resolves.
Local debridement and drainage is possible for some cases of chondritis via an endoscope and surgical laser or laryngotomy. This should only be pursued in horses that have maintained some mobility of the arytenoid cartilage and have minimal enlargement of the arytenoid cartilage with little reduction in the airway diameter.
Horses with enlarged, misshapen, immobile arytenoid cartilages require an arytenoidectomy. Ventriculocordectomy is often performed with arytenoidectomy; the surgical approach for both is via laryngotomy.
In horses with bilateral chondropathy, unilateral arytenoidectomy on the side that is most affected is recommended, however, some surgeons will perform bilateral arytenoidectomy based on severity of disease, despite the high risk of aspiration after this procedure. In horses with bilateral disease, permanent tracheostomy can be pursued, particularly if the horse is not intended for work (Broodmare, pasture companion, etc).
Horses are treated postoperatively with NSAIDs, antimicrobials, rest and maintenance of the temporary tracheotomy until resolution of edema. Coughing and dysphagia are common complications in the early post-operative period. Dysphagia leading to aspiration is a known risk after arytenoidectomy, and owners should be educated about this complication before surgery.
Severe inflammation and infection of the arytenoid cartilage cause enlargement and immobility of the cartilage.
Horses show poor performance, respiratory noise, and/or dyspnea.
Diagnosis is made via endoscopic examination and may be augmented with laryngeal ultrasound.
Treatment requires anti-inflammatories, antimicrobials, airway rest, and usually surgical debridement, drainage, or removal of the affected arytenoid cartilage.
For More Information
Also see pet health content regarding disorders of the larynx in horses Disorders of the Larynx in Horses The larynx is the part of the throat often called the “voice box” in humans. It is located near the top of the trachea. The larynx is composed of muscles and cartilage, and it includes the vocal... read more .