[Equine laryngeal dysplasia - overview of variable clinical presentation based on 6 cases]

Equine laryngeal dysplasia (ELD) is the umbrella term for various malformations of laryngeal structures that arise from the 4th and 6th branchial arches during embryogenesis. The disease is rare and may be subclinical. In symptomatic patients with clinical signs, the clinical presentation is highly variable and is the result of functional limitations of the larynx as well as of the esophageal sphincter. The spectrum of signs may range from respiratory changes such as abnormal respiratory noise, coughing, and at times dyspnea all the way to poor performance, dysphagia, aerophagia, and colic. The most common reason for presentation is abnormal respiratory noise. In the following case series, the clinical signs of 6 affected horses are described and discussed in context with the literature. Furthermore, it is highlighted that the approach to diagnosis is primarily based on clinical examination, endoscopic inspection of the upper airways, and radiography of the laryngeal region. The most common endoscopic findings include right (HLD) and/or left laryngeal hemiplegia (HLS), rostral displacement of the palatopharyngeal arch (RDPA) and dorsal displacement of the soft palate (DDSP). In ELD, these findings may occur on their own or in combination. Since the findings may also be signs of further, more common disorders, misdiagnosis does occur. In the following article, the clinically relevant therapeutic and prognostic key points as well as important aspects on how to avoid common diagnostic pitfalls are discussed.