Squamous cell carcinoma of the larynx and pharynx in horses.

Medical records were reviewed for 11 horses with squamous cell carcinoma of the larynx and/or pharynx. The average age at presentation was 15.3 years. No breed or sex predilection was present. At presentation, 6 of 11 horses were dyspneic and 4 horses had inspiratory stridor. Endoscopy was performed in all cases and was more useful in demonstrating a mass in the laryngopharyngeal region than laryngeal or guttural pouch radiography. Surgical excision was attempted in 3 horses and in 1 horse alleviated clinical signs for 4 months. Ten horses were euthanatized and 1 horse died. Results of this study indicated that laryngopharyngeal squamous cell carcinomas are difficult to surgically excise due to their location, size and invasiveness. Treatment is often not attempted because of the advanced state of the disease at the time of presentation.