Electromyoenterography during normal gastro-intestinal activity, painful or non-painful colic and morphine analgesia, in the horse.

This is a research study that investigates the electrical activities in certain parts of a pony’s digestive system under different conditions: when the pony is at rest, during non-painful colic, and following the administration of morphine. The study reveals many findings, including a change in frequency of the electrical potential that suggests morphine increases activity in certain regions of the digestive system.

Details about the Research Study

• The researchers conducted a study involving ponies. They recorded the electrical potentials – an indication of gastrointestinal activity – from various parts of the ponies’ digestive systems.
• The selected parts of the digestive system included: the antrum (part of the stomach), the duodenum (the first section of the small intestine), the ileum (the final section of the small intestine), and the first part of the colon (the large intestine).
• These potential were recorded in three conditions, namely during normal rest, experiencing non-painful colic, and after the ponies had been administered intravenous morphine.

Key Findings of the Research Study

• When a pony is at rest, their antrum averages five contractions per minute. The small intestine has three kinds of movement: waves that move things along the intestine, contractions that divide the intestine into segments, and random contractions.
• The rate of electrical activity naturally decreased down the length of the pony’s small intestine, from the duodenum to the ileum.
• In the colon, intense motor activity occurred as bursts of electrical potential, at a rate of 20 to 30 times per hour.
• When Morphine was administered intravenously, it significantly increased the frequency of the electrical potentials of the antrum and the longitudinal bands of the colon.
• During non-painful colic, the upper small intestine (cranial) showed continuous hyperactivity. The jejunum (a part of the small intestine) spasmed every minute, and these spasms were unaffected by morphine.
• During painful colic, abdominal pain was accompanied by spasms in the jejunum. However, these spasms and pain were alleviated after administering intravenous morphine. Despite this, the jejunum remained hyperactive, the motility of the colon increased and the antrum became quiet.