Review
Medetomidine sedation in dogs and cats:A review of its pharmacology, antagonism and dose

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Summary

Medetomidine is a relatively new sedative analgesic in dogs and cats but some precautions are required when using it. It is a potent α2-adrenoceptor agonist and stimulates receptors centrally to produce dose-dependent sedation and analgesia and receptors centrally and peripherally to cause marked bradycardia and decrease the cardiac output. While hypotension occurs frequently, higher doses of the sedative can raise the blood pressure due to an affect on peripheral receptors. Slowing of the respiratory rate is a frequent effect of medetomidine with some dogs showing signs of cyanosis. Other actions that follow medetomidine use are slowing of gastrointestinal motility, hypothermia, changes to endocrine function and, occasionally, vomiting and muscle twitching. The clinical use of medetomidine in dogs and cats is discussed. Recommended dose rates are presented along with precautions that should be taken when it is used alone for sedation, as an anaesthetic premedicant or in combination with ketamine, propofol or opioids. Hypoxaemia occurs frequently in dogs given medetomidine and propofol. The actions of medetomidine can be rapidly reversed with the specific α2-adrenoceptor antagonist, atipamezole, which is an advantage because undesirable and sedative actions of medetomidine can be terminated.

References (88)

  • PertovaaraA. et al.

    Involvement of supraspinal and spinal segmental alpha-2-adrenergic mechanisms in the medetomidine-induced antinoception

    Neuroscience

    (1991)
  • ProbstA. et al.

    Distribution of α2-adrenergic receptors in the human brainstem: an autoradiographic study using [3H]p-aminoclonidine

    European Journal of Pharmacology

    (1984)
  • RuffoloR.R.

    Distribution and function of peripheral alpha-adrenoceptors in the cardiovascular system

    Pharmacology, Biochemistry and Behaviour

    (1985)
  • SapR. et al.

    Medetomidine/propofol anaesthesia for gastroduodenal endoscopy in dogs

    Journal of Veterinary Anaesthesia

    (1993)
  • UnnerstallJ.R. et al.

    Distribution of alpha-2 agonist binding sites in the rat and human central nervous system: analyses of some functional, anatomic correlates of the pharmacology effects of clonidine and related adrenergic agents

    Brain Research Review

    (1984)
  • VainioO.

    Propofol infusion anaesthesia in dogs premedicated with medetomidine

    Journal of Veterinary Anaesthesia

    (1991)
  • VainioO. et al.

    Medetomidine, a new sedative and analgesic drug for dogs and cats

    Journal of the Association. of Veterinary Anaesthetists

    (1986/87)
  • VirtanenR. et al.

    Characterization of the selectivity, specificity and potency of medetomidine as an α2-adrenoceptor agonist

    European Journal of Pharmacology

    (1988)
  • AghajanianG.K. et al.

    Alpha2-adrenoceptor mediated hyperpolarisation of locus coeruleus neurons: intracellular studies in vivo

    Science

    (1982)
  • AlibhaiH.I. et al.

    Effects of atropine sulphate and medetomidine hydrochloride combinations on the cardio-pulmonary system in dogs and sheep

    Journal of Veterinary Anaesthesia

    (1993)
  • BartramD.H. et al.

    Effects of combinations of medetomidine/pethidine when used for sedation and preanaesthetic medication in dogs

    Journal of Small Animal Practice

    (1993)
  • BartramD.H. et al.

    Use of medetomidine and butorphanol for sedation in dogs

    Journal of Small Animal Practice

    (1994)
  • BergstromL.

    Cardiovascular and pulmonary effects of a new sedative/analgesic (medetomidine) as a preanaesthetic drug in the dog

    Acta Veterinaria Scandinavica

    (1988)
  • BloorB.C. et al.

    Hemodvnamic and sedative effects of dexmedetomidine in dogs

    Journal of Pharmacology and Experimental Therapeutics

    (1992)
  • BoyajianC.L. et al.

    Anatomical evidence for alpha-2 adrenoceptor heterogeneity: differential autoradiographic distributions of [3H] rauwolscine and [3H] idazoxan in rat brain

    Journal of Pharmacology and Experimental Therapeutics

    (1987)
  • BransonK.R. et al.

    Duration of analgesia induced by epidurally administered morphine and medetomidine in dogs

    Journal of Veterinary Pharmacology and Therapeutics

    (1993)
  • ClarkeK.W. et al.

    Medetomidine, a new sedative-analgesic for use in the dog and its reversal with atipamezole

    Journal of Small Animal Practice

    (1989)
  • ColbyE.D. et al.

    Emetic action of xylazine on the chemoreceptor trigger zone for vomiting in cats

    Journal of Veterinary Pharmacology and Therapeutics

    (1981)
  • Correa-SalesC. et al.

    A hypnotic response to dexmedetomidine, an a,-agonist, is mediated in the locus coeruleus

    Anesthesiology

    (1992)
  • CrightonM.

    Diuresis following medetomidine

    Veterinary Record

    (1990)
  • CullenL.K. et al.

    Xylazine or medetomidine premeditation before propofol anaesthesia

    Veterinary Record

    (1993)
  • DayT.K. et al.

    α2-Adrenergic receptor agonist effects on supraventricular and ventricular automaticity in dogs with complete atrioventricular block

    American Joumal of Veterinary Research

    (1993)
  • DozeV.A. et al.

    Dexmedetomidine produces a hypnotic-anaesthetic action in rats via activation of central alpha-2 adrenoceptors

    Anesthesiology

    (1989)
  • DukeT. et al.

    The analgesic effects of administering fentanyl or medetomidine in the lumbosacral epidural space of chronically catheterised cats

    Journal of Veterinary Anaesthesia

    (1993)
  • EnglandG.C.W. et al.

    The use of medetomidine/fentanyl combinations in dogs

    Acta Veterinaria Scandinavica

    (1989)
  • EwingK.K. et al.

    Reduction of isoflurane anesthetic requirement by medetomidine and its restoration by atipamezole in clogs

    American Journal of Veterinary Research

    (1993)
  • HallL.W. et al.

    Plasma concentrations of medetomidine in clogs following sublingual and intramuscular administration

  • HousmansP.R.

    Effects of dexmedetomidine on contractility, relaxation, and intracellular calcium transients of isolated ventricular myocardium

    Anesthesiology

    (1990)
  • JedruchJ. et al.

    Uterine motor responses to an α2-adrenergic agonist medetomidine hydrochloride in bitches during the end of gestation and the post partumperiod

    Acta Veterinaria Scandinavica

    (1989)
  • KarlssonB.R. et al.

    Effect of dexmedetomidine, a selective and potent α2-agonist, on cerebral blood flow and oxygen consumption during halothane anesthesia in dogs

    Anesthesia and Analgesia

    (1990)
  • KeeganR.D. et al.

    Effects of medetomidine administration on intracranial pressure and cardiovascular variables of isoflurane-anesthetized dogs

    American Journal of Veterinary Research

    (1995)
  • KimuraT. et al.

    The role of central adrenoceptors in the control of vasopressin release and blood pressure

    Endocrinology

    (1981)
  • KoJ.C.H. et al.

    Hemodynamic and anesthetic effects of etomidate infusion in medetomidine-premedicated dogs

    American Journal of Veterinary Research

    (1994)
  • LemkeK.A. et al.

    Alterations in the arrhythmogenic dose of epinephrine after xylazine or medetomidine administration in halo thane-anesthetized dogs

    American Journal of Veterinary Research

    (1993)
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