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Fourth branchial arch defect: a case study



Horses that present with abnormal upper respiratory noise at exercise can have a myriad of different laryngeal and pharyngeal structures collapsing into the airway, and exercising endoscopy provides the only way of providing a definitive diagnosis (or diagnoses in the case of composite collapse). However, a thorough clinical examination, endoscopic examination at rest and other ancillary diagnostic techniques can be very useful in some cases. This case study describes the clinical and endoscopic findings of a horse with suspected fourth branchial arch defect (4-BAD), a syndrome in which laryngeal palpation, radiography and ultrasound can all be very useful in addition to resting and exercising endoscopy when making a diagnosis.