Evaluation of the effects of the opioid agonist morphine on gastrointestinal tract function in horses

  • Boscan P
  • Van Hoogmoed L
  • Farver T
 et al. 
  • 22


    Mendeley users who have this article in their library.
  • 74


    Citations of this article.


OBJECTIVE: To evaluate the effects of morphine administration for 6 days on gastrointestinal tract function in healthy adult horses.

ANIMALS: 5 horses.

PROCEDURES: Horses were randomly allocated into 2 groups in a crossover study. Horses in the treatment group received morphine sulfate at a dosage of 0.5 mg/kg, IV, every 12 hours for 6 days. Horses in the control group received saline (0.9% NaCl) solution at a dosage of 10 mL, IV, every 12 hours for 6 days. Variables assessed included defecation frequency, weight of feces produced, intestinal transit time (evaluated by use of barium-filled spheres and radiographic detection in feces), fecal moisture content, borborygmus score, and signs of CNS excitement and colic.

RESULTS: Administration of morphine resulted in gastrointestinal tract dysfunction for 6 hours after each injection. During those 6 hours, mean +/- SD defecation frequency decreased from 3.1 +/- 1 bowel movements in control horses to 0.9 +/- 0.5 bowel movements in treated horses, weight of feces decreased from 4.1 +/- 0.7 kg to 1.1 +/- 0.7 kg, fecal moisture content decreased from 76 +/- 2.7% to 73.5 +/- 2.9%, and borborygmus score decreased from 13.2 +/- 2.9 to 6.3 +/- 3.9. Mean gastrointestinal transit time was also increased, compared with transit times in control horses.

CONCLUSIONS AND CLINICAL RELEVANCE: Morphine administered at 0.5 mg/kg twice daily decreased propulsive motility and moisture content in the gastrointestinal tract lumen. These effects may predispose treated horses to development of ileus and constipation.

Get free article suggestions today

Mendeley saves you time finding and organizing research

Sign up here
Already have an account ?Sign in

Find this document

Get full text


  • Pedro Boscan

  • Linda M. Van Hoogmoed

  • Thomas B. Farver

  • Jack R. Snyder

Cite this document

Choose a citation style from the tabs below

Save time finding and organizing research with Mendeley

Sign up for free