## Overview Fourth branchial arch defect (also called laryngeal dysplasia or 4-BAD) is a congenital malformation of laryngeal structures derived from the fourth branchial arch. It most often affects the right side and can cause respiratory noise, exercise intolerance, or dysphagia from birth. ## Causes Developmental failure of cartilage and muscle formation (thyroid and cricoid cartilages, associated muscles). ## Diagnosis Endoscopy showing reduced arytenoid abduction or rostral displacement of the palatopharyngeal arch, plus ultrasound, radiographs, or computed tomography confirming cartilage abnormalities. ## Treatment Surgical options are limited and case-dependent. Some horses are managed conservatively if signs are mild. Severe dysphagia or airway obstruction may require more aggressive intervention. ## Recovery and Prognosis Variable. Mild cases may perform adequately. Severe defects limit athletic use or cause ongoing dysphagia. ## Prevention None (congenital).
respiratory noise from birth; dysphagia or nasal return of milk in foals; exercise intolerance; arytenoid dysfunction on endoscopy
## Overview Fourth branchial arch defect (also called laryngeal dysplasia or 4-BAD) is a congenital malformation of laryngeal structures derived from the fourth branchial arch. It most often affects the right side and can cause respiratory noise, exercise intolerance, or dysphagia from birth. ## Causes Developmental failure of cartilage and muscle formation (thyroid and cricoid cartilages, associated muscles). ## Diagnosis Endoscopy showing reduced arytenoid abduction or rostral displacement of the palatopharyngeal arch, plus ultrasound, radiographs, or computed tomography confirming cartilage abnormalities. ## Treatment Surgical options are limited and case-dependent. Some horses are managed conservatively if signs are mild. Severe dysphagia or airway obstruction may require more aggressive intervention. ## Recovery and Prognosis Variable. Mild cases may perform adequately. Severe defects limit athletic use or cause ongoing dysphagia. ## Prevention None (congenital).
respiratory noise from birth; dysphagia or nasal return of milk in foals; exercise intolerance; arytenoid dysfunction on endoscopy