The effect of oxytocin on contractility of the equine oesophagus: a potential treatment for oesophageal obstruction

This study was performed to determine the effect of administration of i.v. oxytocin on the contractility of the musculature associated with the equine oesophagus. Nine clinically normal horses were fitted with a nasogastric tube modified with inflatable latex cuffs. These cuffs were connected to piezoelectric pressure recording devices. Oxytocin in 3 different doses or saline controls were administered i.v. in a randomised block pattern. Systolic blood pressure, ECG, heart rate and nasogastric tube cuff pressures were then measured for 60 min. Administration of oxytocin i.v. at 0.11 and 0.22 iu/kg bwt, resulted in a short-term statistically significant relaxation of the musculature of the equine oesophagus. When oxytocin was administered at 0.11, 0.22 and 0.44 iu/kg bwt, no clinically significant cardiovascular changes were seen. In approximately 5% of the oxytocin administrations, signs of mild short-term abdominal discomfort were observed. In clinical cases of noncomplicated oesophageal obstruction, it is suggested that reduction in tone of oesophageal musculature may result in passage of oesophageal obstructions with reduced risk of oesophageal injury when compared to other traditional treatments.