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

Equine laryngeal dysplasia (ELD) encompasses various congenital malformations of the larynx affecting horses, originating during embryonic development. This study reviews six cases to illustrate the variable clinical signs, diagnostic challenges, and therapeutic considerations associated with ELD.

Overview of Equine Laryngeal Dysplasia (ELD)

• ELD refers to multiple malformations of the laryngeal structures derived from the 4th and 6th branchial arches during embryogenesis.
• The condition is rare and can be asymptomatic (subclinical), meaning some horses may show no obvious signs.
• When symptoms occur, they exhibit high variability due to functional impairments of both the larynx and the esophageal sphincter.
• Symptoms range broadly, including:
• Respiratory abnormalities (abnormal respiratory noise, coughing, dyspnea or difficulty breathing)
• Poor athletic performance
• Swallowing difficulties (dysphagia)
• Excessive air swallowing (aerophagia)
• Colic (abdominal pain)
• Abnormal respiratory noise is the most common reason for horses to be presented for examination.

Clinical Presentation in the Case Series

• The study discusses six affected horses with ELD, demonstrating a spectrum of clinical signs.
• Variability in clinical signs is linked to differences in which laryngeal structures are malformed and how these affect function.
• Both the larynx itself and the esophageal sphincter can be involved, complicating clinical presentation.

Diagnostic Approach

• Diagnosis is based primarily on:
• Clinical examination
• Endoscopic inspection of the upper airways
• Radiography (X-ray) of the laryngeal region
• Common endoscopic findings include:
• Right (HLD) and/or left (HLS) laryngeal hemiplegia—paralysis or weakness of one side of the larynx
• Rostral displacement of the palatopharyngeal arch (RDPA)—forward shifting of a part of the throat arch
• Dorsal displacement of the soft palate (DDSP)—upward dislocation of the soft palate
• These findings may occur singly or in combinations.
• Many of these signs can overlap with other, more common equine disorders, which can lead to misdiagnosis.

Challenges and Pitfalls in Diagnosis

• ELD’s signs mimic those of other respiratory and swallowing disorders, making correct diagnosis challenging.
• A thorough and systematic clinical and endoscopic exam is essential to differentiate ELD from other conditions.
• Misdiagnosis may result in inappropriate treatment or prognostic expectations.

Therapeutic and Prognostic Considerations

• The article discusses key treatment approaches, emphasizing that management depends on the specific functional impairments observed.
• Prognosis varies depending on symptom severity and combination of affected structures.
• Highlighting early and accurate diagnosis improves the potential to optimize outcomes.
• Understanding the wide range of clinical presentations aids in tailoring therapeutic strategies for individual cases.

Summary

• Equine laryngeal dysplasia is a rare congenital disorder with variable clinical signs affecting respiration and swallowing.
• The spectrum of signs, overlapping with other diseases, requires careful and comprehensive diagnostic work-up.
• Accurate diagnosis combining clinical examination, endoscopy, and radiography is crucial to avoid misdiagnosis.
• Appropriate therapeutic intervention and realistic prognosis can then be established, improving horse welfare and performance outcomes.