title: Addition of magnesium sulphate to ropivacaine for spinal analgesia in dogs undergoing tibial plateau levelling osteotomy.
abstract: The aim of this blinded, randomised, prospective clinical trial was to determine whether the addition of magnesium sulphate to spinally-administered ropivacaine would improve peri-operative analgesia without impairing motor function in dogs undergoing orthopaedic surgery. Twenty client-owned dogs undergoing tibial plateau levelling osteotomy were randomly assigned to one of two treatment groups: group C (control, receiving hyperbaric ropivacaine by the spinal route) or group M (magnesium, receiving a hyperbaric combination of magnesium sulphate and ropivacaine by the spinal route). During surgery, changes in physiological variables above baseline were used to evaluate nociception. Arterial blood was collected before and after spinal injection, at four time points, to monitor plasma magnesium concentrations. Post-operatively, pain was assessed with a modified Sammarco pain score, a Glasgow pain scale and a visual analogue scale, while motor function was evaluated with a modified Tarlov scale. Assessments were performed at recovery and 1, 2 and 3 h thereafter. Fentanyl and buprenorphine were administered as rescue analgesics in the intra- and post-operative periods, respectively. Plasma magnesium concentrations did not increase after spinal injection compared to baseline. Group M required less intra-operative fentanyl, had lower Glasgow pain scores and experienced analgesia of longer duration than group C (527.0 ± 341.0 min vs. 176.0 ± 109.0 min). However, in group M the motor block was significantly longer, which limits the usefulness of magnesium for spinal analgesia at the investigated dose. Further research is needed to determine a clinically effective dose with shorter duration of motor block for magnesium used as an additive to spinal analgesic agents.
authors.affiliation: Department of Clinical Sciences and Services, Royal Veterinary College, University of London, Hawkshead Campus, North Mymms, AL97TA Hatfield, Herts, UK. Electronic address: c.adami@rvc.ac.uk.
authors.forename: C
authors.initials: C
authors.lastname: Adami
authors.affiliation: Department of Veterinary Clinical Science, Anaesthesiology and Pain Therapy Division, Vetsuisse Faculty, University of Berne, Länggassstrasse 124, CH-3012 Berne, Switzerland.
authors.forename: D
authors.initials: D
authors.lastname: Casoni
authors.affiliation: Department of Veterinary Clinical Science, Surgery Division, Vetsuisse Faculty, University of Berne, Länggassstrasse 124, CH-3012 Berne, Switzerland.
authors.forename: F
authors.initials: F
authors.lastname: Noussitou
authors.affiliation: Department of Veterinary Clinical Science, Surgery Division, Vetsuisse Faculty, University of Berne, Länggassstrasse 124, CH-3012 Berne, Switzerland.
authors.forename: U
authors.initials: U
authors.lastname: Rytz
authors.affiliation: Department of Veterinary Clinical Science, Anaesthesiology and Pain Therapy Division, Vetsuisse Faculty, University of Berne, Länggassstrasse 124, CH-3012 Berne, Switzerland.
authors.forename: C
authors.initials: C
authors.lastname: Spadavecchia
mesh_terms: D000577:Amides / Q000008:administration & dosage; D000698:Analgesia / Q000662:veterinary*; D000700:Analgesics / Q000008:administration & dosage*; D000701:Analgesics, Opioid / Q000008:administration & dosage; D000779:Anesthetics, Local / Q000008:administration & dosage; D000818:Animals; D002047:Buprenorphine / Q000008:administration & dosage; D004285:Dogs / Q000601:surgery*; D005283:Fentanyl / Q000008:administration & dosage; D008278:Magnesium Sulfate / Q000008:administration & dosage*; D010027:Osteotomy / Q000662:veterinary*; D010147:Pain Measurement / Q000662:veterinary; D010149:Postoperative Pain / Q000662:veterinary; D011446:Prospective Studies; D000077212:Ropivacaine
chemical_list: D000577:Amides; D000700:Analgesics; D000701:Analgesics, Opioid; D000779:Anesthetics, Local; D002047:Buprenorphine; D008278:Magnesium Sulfate; D000077212:Ropivacaine; D005283:Fentanyl
keywords: Analgesia; Dog; Magnesium sulphate; Ropivacaine; Spinal anaesthesia