Effect of spasmolytic analgesic drugs on the motility patterns of the equine small intestine.

The effect of acepromazine, Buscopan (Crown Chemicals), pethidine and methadone was evaluated in ponies prepared with Thiry-Vella (T-V) loops. Motility was assessed by electrophysiological means (bipolar electrodes and strain gauge transducers) and by the passage through the T-V loop of a fluid test meal. Results were obtained from 26 experiments in three ponies and compared with six control experiments, in which saline had been administered to the same ponies. Each pony acted as its own control in each experiment and pre and post treatment values for slow wave frequency, spiking activity, delivery rate and flow rate were compared. Acepromazine reduced electrical activity, but increased volume transport. Buscopan produced little change, while pethidine and methadone both decreased electrical activity, but increased volume transit. These effects may be due to a decrease in tone with resulting increase in luminal volume of the intestine.