Comparison of Recovery Quality Following Medetomidine versus Xylazine Balanced Isoflurane Anaesthesia in Horses: A Retrospective Analysis

Comparison of Xylazine and Lidocaine Infusion versus Medetomidine Continuous Rate Infusion during General Anesthesia with Isoflurane in Horses Undergoing Emergency Laparotomy

(1) The main goals of general anesthesia include pain management and a safe anesthetic protocol for smooth recovery. In this retrospective study, we compared two anesthetic protocols for general anesthesia with isoflurane during emergency laparotomy: sedation with xylazine and the intraoperative infusion of lidocaine (X group) versus medetomidine as a preoperative sedation and intraoperative infusion (M group). (2) The medical records of horses who underwent emergency laparotomies between 2016 and 2023 were reviewed. According to the anesthetic protocol, patients were allocated to the X or M groups. Data about the horse, signalment, history, and anesthetic variables were analyzed. (3) Group X had a significantly higher heart rate (HR), lower respiratory rate (RR) and mean and diastolic arterial pressure (MAP/DAP). A progressive increase in HR and RR was observed in both groups. Group X underwent a decrease in RR and an increase in DAP. In Group M, a decrease in MAP and DAP was observed. Group M exhibited a longer recovery time with similar recovery scores. Both protocols provided safe anesthesia for emergency laparotomy, with minor cardiovascular and respiratory depression. Minor respiratory depression was detected when xylazine was used, while recovery was longer with medetomidine.

The influence of hypoxaemia, hypotension and hypercapnia (among other factors) on quality of recovery from general anaesthesia in horses

OBJECTIVE

To investigate the effect of hypoxaemia, hypotension and hypercapnia, among others, on quality of recovery from general anaesthesia in horses.

STUDY DESIGN

Retrospective, single-centre study.

ANIMALS

A sample of 1226 horses that underwent general anaesthesia between June 2017 and June 2021.

METHODS

Horses and ponies weighing > 200 kg, aged > 6 months, anaesthetized using a xylazine- or medetomidine-isoflurane balanced anaesthesia protocol and presenting a complete anaesthetic record were included. Data were extracted from the clinic record system and from the original anaesthesia records. Recoveries were divided into 'good' and 'bad' based on the available recovery scores. Influence of hypoxaemia [PaO2 < 60 mmHg (7.99 kPa)], hypotension (mean arterial pressure < 70 mmHg for at least 15 minutes) and hypercapnia [PaCO2 > 60 mmHg (7.99 kPa)], anaesthesia protocol, body weight, age, breed, sex, American Society of Anesthesiologists status, type of procedure, emergency or nonemergency, duration of anaesthesia, positioning, times spent in lateral and sternal recumbency during recovery, time until standing and nonassisted or assisted recovery on the assigned recovery score (good/bad) were investigated using generalized linear regression analysis (p < 0.05).

RESULTS

Hypoxaemia and prolonged duration of anaesthesia were significantly associated with a bad recovery score. No other factors had a significant influence on recovery quality.

CONCLUSION AND CLINICAL RELEVANCE

Hypoxaemia and prolonged anaesthesia duration have a negative effect on quality of anaesthetic recovery in horses. Clinically, this highlights the importance of keeping anaesthetic time as short as possible and to monitor oxygenation and treat hypoxaemia as soon as possible.

Xylazine Infusion during Equine Colic Anesthesia with Isoflurane and Lidocaine: A Retrospective Study

This retrospective study investigated the effect of a xylazine infusion on heart rate; mean arterial pressure; blood gases; anesthetic and dobutamine requirements; recovery quality and duration; percentage of death/survival; and days to die/discharge in horses after colic surgery under partial intravenous anesthesia with isoflurane and lidocaine infusion. Anesthetic records of equine colic surgery were reviewed from similar periods in 2020-2021 and 2021-2022. In both groups, after sedation with xylazine 0.7 mg/kg intravenously (IV) and induction with ketamine 2.2 mg/kg and midazolam 0.06 mg/kg IV, anesthesia was maintained with isoflurane and lidocaine (bolus 1.5 mg/kg IV, infusion 2 mg/kg/h). Group L (2020-2021, n = 45) received xylazine 0.2 mg/kg IV before recovery, group XL (2021-2022, n = 44) received xylazine 0.5 mg/kg/h IV intraoperatively. In group XL, minimal (p = 0.04) and average (p = 0.04) heart rate, intraoperative hematocrit (p = 0.001), minimal (p = 0.002) and maximal (p = 0.04) dobutamine administration rate, animals requiring ketamine top-ups (p = 0.04), and the number of days to discharge (p = 0.02), were significantly lower compared to group L. During recovery in group XL, the time to sternal recumbency (p = 0.03) and time to first attempt (p = 0.04) were significantly longer. This retrospective study suggests that a xylazine infusion may have beneficial effects on horses undergoing colic surgery. Further prospective studies are necessary.

Retrospective Study on Risk Factors and Short-Term Outcome of Horses Referred for Colic from 2016 to 2022

Simple Summary

Colic syndrome is the most common out-of-hours call for equine practitioners. In most cases, medical treatment at home is effective for the resolution of the disorders. In 20% of cases, hospital intensive care is required. Several factors have been addressed as predisposing to the disorder. Cardiovascular and hemodynamic variables are the most reliable indicators of the severity of the condition and, thus, are important prognostic factors. The aim of the study was to highlight the predisposing factors and best prognostic clinical signs for discharge in a cohort of horses referred for colic syndrome. Medical records from 2016 to 2022 were examined. One hundred and fifty-seven horses were included in the study. Month and time of admission were the main predisposing factors. Cardiovascular variables (heart rate on admission and after 3–6 h, packed cell volume, capillary refill time, and mucosal membranes) and the presence of gastric reflux were negatively associated with discharge as well as time to standing after surgery. The results from this retrospective study may help the clinician in evaluating prognosis, deciding on the best treatment, and adequately informing the owner of the rates of success.

Abstract

(1) Background: colic syndrome is a multifactorial life-threatening condition in equids. Awareness of predisposing and prognostic indicators is useful to adequately inform the owner of the outcome and plan the best treatment. The aim of the study was to identify the variables associated with short-term survival in a cohort of horses referred for colic to a veterinary teaching hospital; (2) Methods: medical records of horses referred for colic from 2016 to 2022 were retrospectively reviewed. Univariate and multivariate regression models were built to assess the odds ratios of discharge from the hospital, both on the whole sample and in those patients undergoing surgery; (3) Conclusions: Month, time of admission, cardiovascular variables (heart rate on admission and after 3–6 h, packed cell volume, capillary refill time, and mucosal membranes), and presence of gastric reflux were significantly associated with discharge in the univariate regression in all horses and in those surgically treated. In the multivariate regression model, heart rate, packed cell volume, and capillary refill time showed significant association with the outcome in the whole sample. Although comparison between this study and previous studies is difficult due to the number and type of variables included, cardiovascular variables and markers of hypovolemia were also shown to be associated with outcome.