Abstract
The aim of this study was to evaluate and compare the effects of single doses of butorphanol, morphine, and tramadol on gastrointestinal motility in rabbits (Oryctolagus cuniculus) using non-invasive imaging methods, such as radiographic barium follow through and ultrasonographic contraction counts. Time-lapse radiographic and ultrasound examinations were performed before and after a single intramuscular dose of 5 mg kg−1 butorphanol, 10 mg kg−1 morphine, or 10 mg kg−1 tramadol. Pyloric and duodenal contraction counts by ultrasonography and radiographic repletion scores for the stomach and caecum were analysed using a mixed linear model. No significant effect was noted on ultrasound examinations of pyloric and duodenal contractions after administration of an opioid treatment. Morphine had a significant effect on the stomach and the caecum repletion scores, whereas butorphanol had a significant effect only on the caecum repletion score. Tramadol had no significant effect on the stomach or caecum repletion scores. The present findings suggest that a single dose of 5 mg kg−1 butorphanol or 10 mg kg−1 morphine temporarily slows gastrointestinal transit in healthy rabbits, preventing physiological progression of the alimentary bolus without the induction of ileus. In contrast, a single dose of 10 mg kg−1 tramadol has no such effects.
Highlights
One rabbit from the morphine cohort was excluded from the study because it displayed pronounced apathy and anorexia following the baseline radiographic examinations before any treatment was administered
The findings of the present study suggest that a single dose of an opioid can affect gastrointestinal transit in healthy rabbits, and this effect seems to be temporary
While morphine and butorphanol temporarily significantly slowed down progression of the alimentary bolus, no effect was observed after tramadol treatment
Summary
Opioids are known to produce gastrointestinal side effects, such as constipation, in humans [1]. To the authors’ knowledge, only the effects of buprenorphine on gastrointestinal motility have been studied so far. While some studies reported that buprenorphine decreased faecal output without other clinical consequences after several administrations over two days [2,3], another study showed that a single intramuscular (IM) administration of buprenorphine had no effect on gastrointestinal motility in rabbits, i.e., the alimentary bolus smoothly continued its progression [4]. The protocols differed among studies; the former focused on effects related to several administrations, whereas the latter studied the temporary effect of a single high dose of 0.1 mg kg−1
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
