TRANSENDOSCOPIC RESECTION OF PHARYNGEAL C YSTS IN THE STANDING HORSE

Pharyngeal cysts are uncommon in horses (Koch and Tate, 1978; Shoemake r and Haynes, 1992). They might be congenital remnants of the thyroglo ssal duct or of inflammatory or traumatic origin (Koch and Tate, 1978; Stick and Soles, 1980; Haynes et al., 1990; Robertson, 1991; Shoemake r and Haynes, 1992). Suggestive clinical symptoms are an inspiratory a nd/or exspiratory noise, exercise intolerance, nasal discharge and dys phagia (Koch and Tate, 1978; Robertson, 1991; Tulleners, 1991; Shoemak er and Haynes, 1992; Speirs et al., 1992). In the year 1995 four horse s of different breeds between two and eight years of age were diagnose d with pharyngeal cysts in the Clinic of Ruminant and Equine Medicine. The diagnosis was made by endoscopic visualization in ail cases. In t wo horses the general appearance was only slightly altered. Two patien ts were presented with coughing, nasal discharge and dysphagia. Their general appearance was moderatley to severly altered. One horse was pr esented with an intermitient epiglottic entrapment and one horse with a permanent epiglottic entrapment in addition to the pharyngeal cyst. In all cases exstirpation of the cyst was performed transendoscopicall y in the standing horse after sedation with detomidin (8mg/500 kg body weight intravenous; Domosdean, Graub AG) in combination with butorphan ol (10 mg/500 kg bodyweight intravenous; Morphasol, Graub AG) and loca l anesthesia of the pharynx (Lidokain Losung 10% reuli). For transendo scopic resection of the cyst a wire snare (SD-16U, Olympus AG) was fix ed at the base of the cyst via a transnasal or transoral approach. Exc ision was done electrosurgically with a high frequency generator (UES 10; Olympus AG) connected to the wire snare. In three cases it was pos sible to excise the cyst at its base. In one horse the cyst was only p artially removed to avoid perforation of the soft palate. Postoperativ e therapy consistet of sodium penicillin (30,000 IU/kg bodyweight), ge ntamicin (5 mg/kg bodyweight) and flumethason (2.5 mg/ kg bodyweight) twice daily via an intravenous catheter. Duration of this therapy was adapted to the recovery period of the individual horse. All horses ret urned to their prior use within two to four weeks. Because of the simp le technique and the good results the transendoscopic electrosurgical resection of pharyngeal cysts in the standing horse has to be consider ed an alternative therapy to other procedures.