The Veterinary clinics of North America. Equine practice2010; 26(3); 493-514; doi: 10.1016/j.cveq.2010.07.002

Opioid analgesia in horses.

Abstract: Opioid analgesics have been the foundation of human pain management for centuries, and their value in animals has increased since it was proposed that it is the veterinarian's duty to alleviate pain whenever it may occur. Compared with other domesticated species, the horse has benefitted less from the increased understanding of opioid pharmacology in animals, because early literature was overlooked and later work, which examined adverse side effects rather than analgesia, concluded that analgesic and excitatory doses were irreconcilably close. More recent studies have indicated a widening role for opioid analgesics in equine pain management, and radioligand studies have revealed a basis for the equine response pattern to opioid analgesics.
Publication Date: 2010-11-09 PubMed ID: 21056296DOI: 10.1016/j.cveq.2010.07.002Google Scholar: Lookup
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The research article explores the evolving role of opioid analgesics in managing pain in horses. These substances, long employed in human medicine, are shown to be increasingly beneficial in equine pain relief, despite early misgivings due to reported adverse effects.

Historical Context of Opioid Analgesics in Equine Medicine

  • The author begins by noting the long-standing use of opioid analgesics in human medicine, and acknowledges that the role of these drugs has increased in veterinary medicine, particularly since it has been proposed that veterinarians are obligated to alleviate animal pain.
  • Despite these advancements, horses have not benefited as much as other animals from improved understanding of opioid pharmacology. This was primarily due to the early literature on the topic being overlooked, and later studies focusing more on the adverse side effects of the drugs rather than their analgesic (pain-relieving) properties.
  • Early treatments with opioids were seen as problematic in horses due to the perceived closeness of doses required for pain relief (analgesic doses) and the onset of adverse side effects (excitatory doses).

Recent Discoveries on Opioid Analgesics in Horses

  • Recent studies indicate a drastic shift in this perception. These newer studies have highlighted a growing role for opioid analgesics in managing equine pain. The use of opioids in horses has expanded from a last-resort treatment to a viable first-line option for equine pain management.
  • Moreover, radioligand studies have offered an explanation for the patterns observed in the equine responses to opioid analgesics. These studies involve using radioactive substances (radioligands) that can bind to specific cell receptors in order to visualize and quantify cellular processes.
  • This research provides a scientific basis for the enhanced utilization of opioids in equine pain management. As scientists continue to understand the opioid receptors in horses and their response to opioid analgesics, more effective and safer pain management strategies can be developed for these animals.

Cite This Article

Clutton RE. (2010). Opioid analgesia in horses. Vet Clin North Am Equine Pract, 26(3), 493-514.


ISSN: 1558-4224
NlmUniqueID: 8511904
Country: United States
Language: English
Volume: 26
Issue: 3
Pages: 493-514

Researcher Affiliations

Clutton, R Eddie
  • Easter Bush Veterinary Centre, University of Edinburgh, Easter Bush, Roslin, Midlothian EH25 9RG, Scotland, UK.

MeSH Terms

  • Adrenergic alpha-2 Receptor Agonists / adverse effects
  • Adrenergic alpha-2 Receptor Agonists / pharmacology
  • Adrenergic alpha-2 Receptor Agonists / therapeutic use
  • Analgesia / veterinary
  • Analgesics, Opioid / adverse effects
  • Analgesics, Opioid / pharmacology
  • Analgesics, Opioid / therapeutic use
  • Animals
  • Drug Synergism
  • Horse Diseases / drug therapy
  • Horses
  • Morphine / adverse effects
  • Morphine / pharmacology
  • Morphine / therapeutic use
  • Pain / drug therapy
  • Pain / veterinary


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