title: Alfaxalone Anaesthesia Facilitates Electrophysiological Recordings of Nociceptive Withdrawal Reflexes in Dogs (Canis familiaris).
abstract: Naturally occurring canine osteoarthritis represents a welfare issue for affected dogs (Canis familiaris), but is also considered very similar to human osteoarthritis and has therefore been proposed as a model of disease in humans. Central sensitisation is recognized in human osteoarthritis sufferers but identification in dogs is challenging. Electromyographic measurement of responses to nociceptive stimulation represents a potential means of investigating alterations in central nociceptive processing, and has been evaluated in conscious experimental dogs, but is likely to be aversive. Development of a suitable anaesthetic protocol in experimental dogs, which facilitated electrophysiological nociceptive withdrawal reflex assessment, may increase the acceptability of using the technique in owned dogs with naturally occurring osteoarthritis. Seven purpose bred male hound dogs underwent electromyographic recording sessions in each of three states: acepromazine sedation, alfaxalone sedation, and alfaxalone anaesthesia. Electromyographic responses to escalating mechanical and electrical, and repeated electrical, stimuli were recorded. Subsequently the integral of both early and late rectified responses was calculated. Natural logarithms of the integral values were analysed within and between the three states using multi level modeling. Alfaxalone increased nociceptive thresholds and decreased the magnitude of recorded responses, but characteristics of increasing responses with increasing stimulus magnitude were preserved. Behavioural signs of anxiety were noted in two out of seven dogs during recordings in the acepromazine sedated state. There were few significant differences in response magnitude or nociceptive threshold between the two alfaxalone states. Following acepromazine premedication, induction of anaesthesia with 1-2 mg kg-1 alfaxalone, followed by a continuous rate infusion in the range 0.075-0.1 mg kg-1 min-1 produced suitable conditions to enable assessment of spinal nociceptive processing in dogs, without subjecting them to potentially aversive experiences. This methodology may be appropriate for obtaining electrophysiological nociceptive withdrawal reflex data in client-owned dogs with naturally occurring osteoarthritis.
authors.affiliation: School of Veterinary Sciences, University of Bristol, Bristol, United Kingdom.
authors.forename: James
authors.initials: J
authors.lastname: Hunt
authors.affiliation: School of Veterinary Sciences, University of Bristol, Bristol, United Kingdom.
authors.forename: Jo
authors.initials: J
authors.lastname: Murrell
authors.affiliation: Comparative Pain Research Laboratory, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, United States of America.
authors.forename: David
authors.initials: D
authors.lastname: Knazovicky
authors.affiliation: Division of Animal Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, United Kingdom.
authors.forename: John
authors.initials: J
authors.lastname: Harris
authors.affiliation: Division of Animal Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, United Kingdom.
authors.forename: Sara
authors.initials: S
authors.lastname: Kelly
authors.affiliation: School of Veterinary Sciences, University of Bristol, Bristol, United Kingdom.
authors.forename: Toby G
authors.initials: TG
authors.lastname: Knowles
authors.affiliation: Comparative Pain Research Laboratory, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, United States of America.|Center for Pain Research and Innovation, UNC School of Dentistry, Chapel Hill, North Carolina, United States of America.|Comparative Medicine Institute, North Carolina State University, Raleigh, North Carolina, United States of America.
authors.forename: B Duncan X
authors.initials: BD
authors.lastname: Lascelles
mesh_terms: D000758:Anesthesia / Q000379:methods*; D000777:Anesthetics / Q000008:administration & dosage*; D000818:Animals; D003243:Consciousness / Q000187:drug effects; D004285:Dogs; D055724:Electrophysiological Phenomena; D008297:Male; D010003:Osteoarthritis / Q000175:diagnosis* / Q000503:physiopathology / Q000662:veterinary; D010146:Pain / Q000175:diagnosis* / Q000188:drug therapy / Q000662:veterinary; D011277:Pregnanediones / Q000008:administration & dosage*; D012018:Reflex / Q000187:drug effects
chemical_list: D000777:Anesthetics; D011277:Pregnanediones; C006477:alphaxalone