Paralaryngeal abscess with laryngeal hemiplegia and fistulation in a horse.

A three year old Thoroughbred filly was examined because of bilateral nasal discharge and external swelling of the left laryngeal area. Endoscopy revealed an enlarged left arytenoid cartilage, left laryngeal hemiplegia and drainage of purulent material into the lumen of the larynx. Radiographs showed a large fluid and gas filled cavity overlying the caudal larynx and cranial trachea. Surgical drainage and debridement of the abscess led to complete healing by secondary intention. Laryngeal ventriculectomy was performed as a treatment for left laryngeal hemiplegia, but a grave prognosis for respiratory soundness was given due to the extensive laryngeal fibrosis. The etiology of the Staphylococcus aureus abscess is unknown but may have originated from oral trauma to the larynx.