title: Physiological and analgesic effects of continuous-rate infusion of morphine, butorphanol, tramadol or methadone in horses with lipopolysaccharide (LPS)-induced carpal synovitis.
abstract: BACKGROUND
  Continuous-rate infusion (CRI) of drugs results in more stable plasma drug concentrations than administration of intermittent boluses, thus providing greater stability of physiological parameters. The aim of this study was to evaluate the physiologic and analgesic effects of the administration of morphine, butorphanol, tramadol or methadone by CRI in horses with induced synovitis of the radiocarpal joint.
  
  
  RESULTS
  Increased values of cardiorespiratory parameters and body temperature were observed in all groups after initiation of opioid administration, and these increases were sustained throughout the CRI period. Morphine, butorphanol and methadone each caused a reduction in gut sounds, and this effect was greatest in animals that received morphine. Administration of morphine or methadone reduced the degree of lameness after the end of intravenous infusion. Administration of tramadol did not alter the degree of lameness in the animals.
  
  
  CONCLUSIONS
  CRI of morphine or methadone, but not butorphanol or tramadol, provided analgesia in horses with carpal synovitis. All of these opioids increased cardiovascular and respiratory parameters and reduced gut sounds during CRI.
authors.affiliation: Department of Veterinary Medicine, University of São Paulo, Duque de Caxias Norte ave 225, Pirassununga, ZIP 13635-900, SP, Brazil. carregaro@usp.br.
authors.forename: Adriano B
authors.initials: AB
authors.lastname: Carregaro
authors.affiliation: College of Veterinary Medicine, Federal University of South Border, Realeza, PR, Brazil. gabrielle.freitas@uffs.edu.br.
authors.forename: Gabrielle C
authors.initials: GC
authors.lastname: Freitas
authors.affiliation: Department of Veterinary Medicine, University of São Paulo, Duque de Caxias Norte ave 225, Pirassununga, ZIP 13635-900, SP, Brazil. martinavet01@usp.br.
authors.forename: Martina H
authors.initials: MH
authors.lastname: Ribeiro
authors.affiliation: Department of Veterinary Medicine, University of São Paulo, Duque de Caxias Norte ave 225, Pirassununga, ZIP 13635-900, SP, Brazil. nathaliavxavier@gmail.com.
authors.forename: Nathalia V
authors.initials: NV
authors.lastname: Xavier
authors.affiliation: Department of Veterinary Medicine, University of São Paulo, Duque de Caxias Norte ave 225, Pirassununga, ZIP 13635-900, SP, Brazil. redoria@usp.br.
authors.forename: Renata G S
authors.initials: RG
authors.lastname: Dória
mesh_terms: D000698:Analgesia / Q000379:methods / Q000662:veterinary*; D000701:Analgesics, Opioid / Q000008:administration & dosage*; D000818:Animals; D002077:Butorphanol / Q000008:administration & dosage*; D050824:Carpal Joints; D006734:Horse Diseases / Q000188:drug therapy*; D006736:Horses; D007262:Infusions, Intravenous / Q000662:veterinary; D007794:Lameness, Animal; D008070:Lipopolysaccharides / Q000494:pharmacology; D008691:Methadone / Q000008:administration & dosage*; D009020:Morphine / Q000008:administration & dosage*; D013585:Synovitis / Q000139:chemically induced / Q000188:drug therapy / Q000662:veterinary*; D014147:Tramadol / Q000008:administration & dosage*
chemical_list: D000701:Analgesics, Opioid; D008070:Lipopolysaccharides; D014147:Tramadol; D009020:Morphine; D002077:Butorphanol; D008691:Methadone