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

This research studied how certain spasmolytic analgesic drugs affected the motility, or contraction movements, of the small intestine in ponies. The response to these drugs was measured through various electrophysiological means and tracking the progress of a fluid test meal through the intestine.

Experimental Design

• The researchers created Thiry-Vella (T-V) loops, a type of intestinal bypass, in ponies to measure the effect of the drugs.
• Bipolar electrodes and strain gauge transducers, used to measure pressure changes, were used to assess motility.
• The passage of a fluid test meal through the T-V loop was also used to measure the effect of the drugs.
• The drugs tested were acepromazine, Buscopan, pethidine and methadone.
• Results from these 26 experiments were compared to six control experiments where only saline was administered to the ponies.
• In this within-subjects design, each pony served as its own control, allowing for comparison of pre and post treatment values.

Findings

• Acepromazine reduced electrical activity in the intestine, indicating decreased muscular contraction, but increased the volume transport, suggesting improved intestinal movement of contents.
• Buscopan produced minimal change in both electrical activity and volume transport.
• Both pethidine and methadone decreased electrical activity but increased volume transit.

Conclusions

• The research suggested these drugs may decrease intestinal tone, reducing contraction strength, but this results in an increase in the internal volume of the intestine.
• This increase in volume allows more intestinal content to move through, which could be beneficial if the goal of treatment is to improve content transit.