The chemical name for tramadol hydrochloride is (±)cis-2-[(dimethylamino)-methyl]-1-(3-methoxy-phenyl)-cyclo-hexanol hydrochloride.1 Tramadol is a centrally acting analgesic that is structurally related to codeine and morphine; it consists of 2 enantiomers, which contribute to analgesic activity via different mechanisms. (+)-Tramadol and the metabolite (+)-O-desmethyl-tramadol are agonists of the μ-opioid receptor. (+)-Tramadol additionally inhibits serotonin reuptake, and (-)-tramadol inhibits norepinephrine reuptake, thus enhancing inhibitory effects on pain transmission pathways in the spinal cord.2,3 Tramadol has rarely been associated with respiratory or cardiovascular depression in humans, even in large doses, and this set it apart from other opioid receptor agonists. In addition, a minimal incidence of constipating effects and low likelihood for development of tolerance and dependence make this a valuable agent for clinical use.3,4
Caudal epidural anesthesia is used to provide analgesia and relaxation in standing cattle for surgery of the tail, perineum, penis, anus, rectum, vagina, and vestibule.5 Obstetric indications in large animals include surgical treatment of parturient injuries, the performance of simple embryotomies, and inhibition of straining to facilitate manipulative correction of fetal malpresentations and reduction of the prolapsed uterus.5–7 When local anesthetics agents are administered via epidural injection, they affect motor and sensory nerves. Motor dysfunction resulting in severe ataxia and recumbency is a particular disadvantage for surgery when it is desirable that the animal should remain standing.7
In other studies,8 investigators determined that epidurally administered tramadol induces analgesia in the perineal and sacral regions in horses. In humans undergoing minor surgical procedures with local anesthesia, preoperative administration of tramadol SC extends the pain-free period and decreases the need for additional analgesia after surgery, compared with the effects of lidocaine injection alone.9 Tramadol administered via the epidural route also induces analgesia in humans10,11 and dogs.12 To the authors’ knowledge, no studies have been performed to investigate the effects of tramadol after epidural administration in cattle. The purpose of the study reported here was to evaluate whether tramadol administered via caudal epidural injection induces perineal analgesia in cattle at a dose of 1, 2, or 3 mg/kg and to determine the duration and extent of analgesic effects. Sedation, ability to control voluntary muscular movements, and effects on heart rate, respiratory rate, and rectal temperature were also assessed.
Tramadol hydrochloride injection 50 mg/mL, Panther Ltd, London, England.
Medical digital thermometer, Ever Prosper (Suzhou) Co Ltd, Suzhou, China.
SPSS 9, Standard Version, SPSS Inc, Chicago, Ill.
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Guedes-Alonso GP, Natalini CC, Robinson EP, et alEpidural administration of tramadol as an analgesic technique in dogs submitted to stifle surgery. Int J Appl Res Vet Med 2005;3:351–359.
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Gomez-De-Segura IA, De-Rossi R, Santos M, et alEpidural injection of ketamine for perineal analgesia in horse. Vet Anesth 1998;27:384–391.
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Jou I-M, Chu K-S, Chen H-H, et alThe effects of intrathecal tramadol on spinal somatosensory-evoked potentials and motor-evoked responses in rats. Anesth Analg 2003;96:783–788.
Mert T, Gunes Y, Guven M, et alComparison of nerve conduction blocks by an opioid and a local anesthetic. Eur J Pharmacol 2002;439:77–81.
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Fahim MR, Bahy Eldeen HM, Saad W. The addition of sufentanil, tramadol or dexmedetomidine to lidocaine for intravenous regional anaesthesia. Egypt J Anaesth 2005;21:283–288.
Kuai JK, Chai W, Yu DH, et alAnalgesic effect of epidural tramadol and midazolam injection after osteoarthropathy operation. Chin J Clin Rehabil 2005;9:108–109.
Faleiros RR, Alves GS, Andrade VG, et alEpidural analgesia with tramadol and morphine in a donkey with oncologic pain. J Vet Emerg Crit Care 2004;14:1–17.
Elghazali M, Barezaik IM, Abdel Hadi AA, et alThe pharmacokinetics, metabolism and urinary detection time of tramadol in camels. Vet J 2008;178:272–277.