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Subepiglottic Cyst in Horses


Bonnie R. Rush

, DVM, MS, DACVIM, Equine Internal Medicine, College of Veterinary Medicine, Kansas State University

Last full review/revision Jan 2014 | Content last modified Jan 2014
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Subepiglottic cysts are an uncommon cause of respiratory noise in young horses. They are likely present from birth but remain undetected until the horse begins exercise training. These cysts are suspected to arise from remnants of the thyroglossal duct. Clinical signs include respiratory noise and exercise intolerance. Large cysts may produce coughing, dysphagia, and aspiration in foals. Diagnosis is determined by endoscopic examination of the upper respiratory tract. The cyst appears as a smooth-walled, fluctuant mass that contains thick, yellow, mucoid material. Occasionally, the mass is not visible in the nasopharynx, and oral examination under general anesthesia may be required to identify it. Histologically, subepiglottic cysts are lined with a combination of stratified squamous and pseudostratified columnar epithelium. Treatment involves complete removal of the secretory lining of the cyst. Rupture of the cyst results in immediate decompression, but recurrence is common. The most common approach is ventral laryngotomy, although transendoscopic Nd:YAG laser surgery has been used for complete excision.

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An obese, 13-year-old, neutered male Pomeranian is brought to the veterinarian because of a cough that has worsened over the last 3 to 4 months. His owner reports that the cough sounds like a “goose honk,” occurs when the dog is excited (e.g., when the doorbell rings), and is unproductive of sputum. The dog then appears to have trouble breathing after coughing. On physical examination, auscultation of the heart and lungs is normal, and the veterinarian is unable to stimulate the cough. The owner declines thoracic x-rays due to financial concerns. Which of the following is the most likely diagnosis?
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