{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,27]],"date-time":"2026-08-27T13:39:38Z","timestamp":1787837978468,"version":"build-2784847793"},"reference-count":50,"publisher":"American Veterinary Medical Association (AVMA)","issue":"6","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["ajvr"],"published-print":{"date-parts":[[2012,6]]},"abstract":"<jats:title>Abstract<\/jats:title>\n<jats:p><jats:bold>Objective<\/jats:bold>\u2014To compare the cardiorespiratory, gastrointestinal, analgesic, and behavioral effects between IV and IM administration of morphine in conscious horses with no signs of pain.<\/jats:p>\n<jats:p><jats:bold>Animals<\/jats:bold>\u20146 healthy adult horses.<\/jats:p>\n<jats:p><jats:bold>Procedures<\/jats:bold>\u2014Horses received saline (0.9% NaCl) solution (IM or IV) or morphine sulfate (0.05 and 0.1 mg\/kg, IM or IV) in a randomized, masked crossover study design. The following variables were measured before and for 360 minutes after drug administration: heart and respiratory rates; systolic, diastolic, and mean arterial blood pressures; rectal temperature; arterial pH and blood gas variables; intestinal motility; and response to thermal and electrical noxious stimuli. Adverse effects and horse behavior were also recorded. Plasma concentrations of morphine, morphine-3-glucuronide, and morphine-6-glucuronide were measured via liquid chromatography\u2013mass spectrometry.<\/jats:p>\n<jats:p><jats:bold>Results<\/jats:bold>\u2014No significant differences in any variable were evident after saline solution administration. Intravenous and IM administration of morphine resulted in minimal and short-term cardiorespiratory, intestinal motility, and behavioral changes. A decrease in gastrointestinal motility was detected 1 to 2 hours after IM administration of morphine at doses of 0.05 and 0.1 mg\/kg and after IV administration of morphine at a dose of 0.1 mg\/kg. Morphine administration yielded no change in any horse's response to noxious stimuli. Both morphine-3-glucuronide and morphine-6-glucuronide were detected in plasma after IV and IM administration of morphine.<\/jats:p>\n<jats:p><jats:bold>Conclusions and Clinical Relevance<\/jats:bold>\u2014Clinically relevant doses of morphine sulfate yielded minimal and short-term behavioral and intestinal motility effects in healthy horses with no signs of pain. Neither dose of morphine affected their response to a noxious stimulus.<\/jats:p>","DOI":"10.2460\/ajvr.73.6.799","type":"journal-article","created":{"date-parts":[[2012,5,23]],"date-time":"2012-05-23T20:02:35Z","timestamp":1337803355000},"page":"799-808","source":"Crossref","is-referenced-by-count":56,"title":["Cardiorespiratory, gastrointestinal, and analgesic effects of morphine sulfate in conscious healthy horses"],"prefix":"10.2460","volume":"73","author":[{"given":"Juliana P.","family":"Figueiredo","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"William W.","family":"Muir","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Richard","family":"Sams","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1272","reference":[{"key":"ref1","series-title":"Vet Clin North Am Equine Pract","doi-asserted-by":"publisher","first-page":"705","DOI":"10.1016\/S0749-0739(17)30140-2","article-title":"Analgesia","volume":"15","author":"Clark","year":"1999"},{"key":"ref2","series-title":"Vet Clin North Am Equine Pract","doi-asserted-by":"publisher","first-page":"117","DOI":"10.1016\/S0749-0739(01)00003-7","article-title":"Management of equine orthopedic pain","volume":"18","author":"Baller","year":"2002"},{"key":"ref3","series-title":"Vet Clin North Am Equine Pract","doi-asserted-by":"publisher","first-page":"47","DOI":"10.1016\/S0749-0739(02)00011-1","article-title":"Use of opioids for pain and anesthetic management in horses","volume":"18","author":"Bennett","year":"2002"},{"key":"ref4","series-title":"Acta Anaesthesiol Scand","doi-asserted-by":"publisher","first-page":"94","DOI":"10.1111\/j.1399-6576.1997.tb04623.x","article-title":"Pharmacology and mechanisms of opioid analgesic activity","volume":"41","author":"Yaksh","year":"1997"},{"key":"ref5","series-title":"Vet Anaesth Analg","doi-asserted-by":"publisher","first-page":"172","DOI":"10.1046\/j.1467-2995.2003.00143.x","article-title":"Comparison of opioid and alpha-2 adrenergic receptor binding in horse and dog brain using radioligand auroradigraphy","volume":"30","author":"Hellyer","year":"2003"},{"key":"ref6","series-title":"Am J Vet Res","doi-asserted-by":"publisher","first-page":"1408","DOI":"10.2460\/ajvr.2001.62.1408","article-title":"Evaluation of opioid receptors in synovial membranes of horses","volume":"62","author":"Sheehy","year":"2001"},{"key":"ref7","series-title":"Am J Vet Res","first-page":"217","article-title":"Effects of butorphanol, flunixin, levorphanol, morphine and xylazine in ponies","volume":"45","author":"Kalpravidh","year":"1984"},{"key":"ref8","series-title":"J Equine Med Surg","first-page":"102","article-title":"Pharmacology review: actions of central stimulant drugs in the horse II","volume":"3","author":"Tobin","year":"1979"},{"key":"ref9","series-title":"J Equine Med Surg","first-page":"284","article-title":"The pharmacology of narcotic analgesics in the horse III. 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