Introduction

• Alpha-2 agonists are widely used for their sedative properties as part of sedation Sedation or sedative protocol and pre-anaesthetic medication Anesthetic premedication: overview protocols in cats and dogs.
• Alongside their sedative effects alpha-2 agonists also have an analgesic action and this can be advantageous in the provision of multi-modal analgesia protocols.
• The analgesic action of alpha-2 agonists is of relatively short duration compared with the sedative effects of this class of drug, therefore to achieve sustained analgesia the alpha-2 agonist must be given by continuous rate infusion.
• Synergistic analgesic effects are well documented between alpha-2 agonists and opioid drugs Analgesia: opioid.
• Alpha-2 agonists have well recognized effects on the cardiovascular system and these must be considered when deciding whether administering an alpha-2 agonist for analgesia is indicated in a particular patient.
• Administration of the alpha-2 antagonist atipamezole Atipamezole will reverse both the sedative and analgesic effects of alpha-2 agonists.

Analgesia: mechanism of action

Alpha-2 agonist drugs used in cats and dogs

Clinical use of medetomidine and dexmedetomidine for analgesia in cats and dogs

Side effects of alpha-2 agonists

Further Reading

Publications

Refereed papers

• Recent references from PubMed and VetMedResource.
• Slingsby L S, Murrell J C, Taylor P M (2010) Combination of dexmedetomidine with buprenorphine enhances the antincociceptive effect to a thermal stimulus in the cat compared with either agent alone. Vet Anaesth Analg 37 (2), 162-170 PubMed.
• Valtolina C, Robben J H, Uilenreef J et al (2009) Clinical evaluation of the efficacy and safety of a constant rate infusion of dexmedetomidine for postoperative pain management in dogs. Vet Anaesth Analg 36 (4), 369-383 PubMed.
• Lin G Y, Robben J H, Murrell J C et al (2008) Dexmedetomidine constant rate infusion for 24 hours during and after propofol or isoflurane anaesthesia in dogs. Vet Anaesth Analg 35 (2), 141-153 PubMed.
• Uilenreef J J, Murrell J C, McKusick B C et al (2008) Dexmedetomidine continuous rate infusion during isoflurane anaesthesia in canine surgical patients. Vet Anaesth Analg 35 (1), 1-12 PubMed.
• Murrell J C, Hellebrekers L J (2005) Medetomidine and dexmedetomidine: a review of cardiovascular effects and antinociceptive properties in the dog. Vet Anaesth Analg 32 (3), 117-127 PubMed.
• Sinclair M D (2003) A review of the physiological effects of alpha-2 agonists related to clinical use of medetomidine in small animal practice. Can Vet J 44 (11), 885-897 PubMed.