Evaluation of total intravenous anesthesia with propofol-guaifenesin-medetomidine and alfaxalone-guaifenesin-medetomidine in Thoroughbred horses undergoing castration

Abstract

Anesthetic and cardiorespiratory effects of total intravenous anesthesia (TIVA) technique using propofol-guaifenesin-medetomidine (PGM) and alfaxalone-guaifenesin-medetomidine (AGM) were preliminarily evaluated in Thoroughbred horses undergoing castration. Twelve male Thoroughbred horses were assigned randomly into two groups. After premedication with intravenous (IV) administrations of medetomidine (5.0 µg/kg) and butorphanol (0.02 mg/kg), anesthesia was induced with guaifenesin (10 mg/kg IV), followed by either propofol (2.0 mg/kg IV) (group PGM: n=6) or alfaxalone (1.0 mg/kg IV) (group AGM: n=6). Surgical anesthesia was maintained for 60 min at a constant infusion of either propofol (3.0 mg/kg/hr) (group PGM) or alfaxalone (1.5 mg/kg/hr) (group AGM), in combination with guaifenesin (80 mg/kg/hr) and medetomidine (3.0 µg/kg/hr). Responses to surgical stimuli, cardiorespiratory values, and induction and recovery characteristics were recorded throughout anesthesia. During anesthesia induction, one horse paddled in group PGM. All horses from group AGM were maintained at adequate anesthetic depth for castration. In group PGM, 3 horses showed increased cremaster muscle tension and one showed slight movement requiring additional IV propofol to maintain surgical anesthesia. No horse exhibited apnea, although arterial oxygen tension decreased in group AGM to less than 60 mmHg. Recovery quality was good to excellent in both groups. In conclusion, TIVA using PGM and AGM infusion was available for 60 min anesthesia in Thoroughbred horses. TIVA techniques using PGM and AGM infusion provided clinically acceptable general anesthesia with mild cardiorespiratory depression. However, inspired air should be supplemented with oxygen to prevent hypoxemia during anesthesia.

Clinical pharmacokinetics and pharmacodynamics of intravenous alfaxalone in young Thoroughbred horses premedicated with medetomidine and midazolam

“…2 Aoki and others reported that the mean induction time in horses premedicated with medetomidine, butorphanol and guaifenesin followed by 1 mg/kg of alfaxalone was 49 seconds. 9 The characteristics of induction in our current study were similar to the results of these previous studies, and the 1 mg/kg of alfaxalone was considered to be an appropriate dose for the induction of anaesthesia in young Thoroughbred horses when they are well sedated before induction. A signiicant decrease in HR was reported in horses ater administration of medetomidine 5-10 µg/kg.…”

“…Goodwin and others reported that the mean induction time in colts administered 1 mg/kg of alfaxalone after sedation with acepromazine, medetomidine and guaifenesin was 36 seconds 2 . Aoki and others reported that the mean induction time in horses premedicated with medetomidine, butorphanol and guaifenesin followed by 1 mg/kg of alfaxalone was 49 seconds 9 . The characteristics of induction in our current study were similar to the results of these previous studies, and the 1 mg/kg of alfaxalone was considered to be an appropriate dose for the induction of anaesthesia in young Thoroughbred horses when they are well sedated before induction.…”

“…The clinical usefulness of alfaxalone CRI in horses as part of TIVA 1 4 9 15 or partial intravenous anaesthesia 24 has been reported. Although we did not investigate the pharmacokinetics of alfaxalone under repeated administration or CRI, our results in the current study would act as basic data for further investigations in TIVA.…”

Clinical effect of a constant rate infusion of alfaxalone in isoflurane-anesthetized goats undergoing an experimental procedure: a pilot study

“…Similarly, in desflurane-anesthetized sheep, infusion of alfaxalone at a rate of 0.07 mg/kg/min results in a decrease of desflurane requirements to maintain a surgical depth of anesthesia (Granados et al, 2012). Also, co-administration of a fentanyl CRI (10 µg/kg/h) results in a significant decrease of the alfaxalone infusion rate in dogs (Dehuisser et al, 2017), while combinations with medetomidine (3 -5 µg/kg/h) alone or with either butorphanol (30 µg/kg/h) or guaifenesin (80 mg/kg/h) have been demonstrated to reduce the alfaxalone dose regimen (1.5 -2 mg/kg/h or 0.025 -0.033 mg/kg/min) for TIVA in horses (Goodwin et al, 2013;Ohmura et al, 2016;Aoki et al, 2017). In goats, a significant reduction of the alfaxalone CRI down to 0.02 mg/kg/min has been observed after a combination with either midazolam (0.1 -0.9 mg/ kg/h) or fentanyl (5 -30 µg/kg/h) (Dzikiti et al, 2015;Dzikiti et al, 2016).…”

Anaesthetic and cardiopulmonary parameters of dogs administered propofol-acepromazine-butorphanol or propofol-acepromazine-buprenorphine anaesthesia

“…Author(s) agree that this article remain permanently open access under the terms of the Creative Commons Attribution License 4.0 International License recovery times (Adetunji et al, 2002). Smooth inductions and short recovery times are peculiar characteristics of propofol which qualifies it to be used as a constant rate infusion for maintenance of anaesthesia (Aoki et al, 2017).…”