Pharmacokinetics, intraoperative effect and postoperative analgesia of tramadol in cats

Res Vet Sci. 2011 Jun;90(3):503-9. doi: 10.1016/j.rvsc.2010.07.015. Epub 2010 Aug 13.


Tramadol is a synthetic codeine analogue used as an analgesic in human and veterinary medicine, but not approved for use in cats. Tramadol (2 mg/kg) was administered intravenously (IV) as preoperative analgesic in 12 cats (6 males) undergoing surgical gonadectomy. The pharmacokinetic profile of the drug and its O-desmethyl metabolite were determined in 8 animals (4 males), while intraoperative effects and postoperative analgesia, estimated by subjective pain score (0-24), were evaluated in all. Mean intraoperative isoflurane consumption was reduced, but hypoventilation was not observed. Sex-related differences were not observed, particularly in terms of postoperative analgesia: rescue analgesic was never administered. Concentrations of the active O-desmethyl metabolite were persistently high in all the animals. Considering the results obtained in this study, tramadol, at the dose of 2 mg/kg IV, did not produce any evident intraoperative cardiorespiratory side effects and with additional investigation may prove to be an appropriate intraoperative analgesic in cats undergoing gonadectomy.

MeSH terms

  • Analgesia / veterinary*
  • Animals
  • Cats
  • Dose-Response Relationship, Drug
  • Female
  • Injections, Intravenous / veterinary
  • Intraoperative Period
  • Male
  • Narcotics / administration & dosage
  • Narcotics / blood
  • Narcotics / pharmacokinetics*
  • Narcotics / pharmacology
  • Pain Measurement / veterinary
  • Postoperative Period
  • Tramadol / administration & dosage
  • Tramadol / blood
  • Tramadol / pharmacokinetics*
  • Tramadol / pharmacology


  • Narcotics
  • Tramadol