Total intravenous anaesthesia with ketamine, medetomidine and guaifenesin compared with ketamine, medetomidine and midazolam in young horses anaesthetised for computerised tomography.

The research article investigates the comparative efficacy of using midazolam and guaifenesin in combination with alpha-2 agonist and ketamine for intravenous anaesthesia in young horses scheduled for computed tomography. The study finds midazolam to be a suitable alternative to guaifenesin, producing clinically comparable quality of anaesthesia, but offers better recovery quality.

Research Objective and Methodology

• This study aimed to compare the use of the anaesthesia combinations ketamine-medetomidine-guaifenesin (KMG) and ketamine-medetomidine-midazolam (KMM) for total intravenous anaesthesia in young horses undergoing computed tomography.
• There was no previous information comparing midazolam with guaifenesin when used in such combinations in horses, which necessitated this research.
• The study was a prospective, randomised, blinded, crossover trial involving fourteen weanling horses. All horses received medetomidine and anaesthesia was induced with ketamine.
• The horses received infusions of either KMG or KMM on separate occasion for 50 minutes.
• Throughout the study, the researchers assessed cardiorespiratory variables and anaesthetic depth every 5-10 minutes.
• Recovery times after the infusions were also recorded, and the quality of recovery was evaluated using a composite score system (CSS), simple descriptive scale (SDS), and visual analogue scale (VAS).

Results and Conclusion

• The infusions of both mixtures produced uneventful anaesthesias, with no difference in the additional anaesthetic requirements and minimal differences in cardiopulmonary variables.
• All the horses recovered without incident and there was no significant difference in recovery times.
• The quality of anaesthetic recovery was significantly better for the horses that received KMM compared to those that received KMG, as is indicated by the CSS, SDS, and VAS scores.
• The researchers concluded that midazolam serves as a fitting substitute for guaifenesin when co-infused with ketamine and medetomidine for anaesthesia in young horses undergoing noninvasive procedures.
• While both infusions create a clinically similar quality of anaesthesia, recovery from anaesthesia is better following an infusion of KMM.

Study Limitation

• The researchers noted that the study’s findings could be limited by the fact that no surgical stimulus was applied, and the weanlings studied may not accurately represent the general horse population.