Background: Flumazenil antagonises the actions of benzodiazepines. There has been no prior research specifically investigating this anaesthetic reversal agent for horses.Objectives: To determine the effects of flumazenil administration in horses on (a) ventilatory parameters after midazolam-ketamine induction and maintenance with isoflurane in oxygen and on (b) the characteristics of recovery from general anaesthesia.Study design: Blinded, randomised, crossover experiment.Methods: Six horses were randomly assigned to receive high-dose flumazenil (F high , 20 µg/kg), low-dose flumazenil (F low , 10 µg/kg) and saline (control). Cardioventilatory parameters were monitored. After 90 minutes of isoflurane anaesthesia, a bolus of F high , F low or saline was administered i.v. The horses were recovered using head and tail rope assistance. The times to first movement, to achievement of sternal recumbency, to the first attempt to stand and the total recovery time were determined.The recovery quality was evaluated using a 115-point recovery scoring system. The cardioventilatory parameters and recovery times were analysed using mixed-effects regression analyses. Intraclass correlation (ICC) analysis was used to evaluate the recovery scores. A Mann-Whitney U test assessed the relationship between recovery score and flumazenil administration.Results: A significant difference with flumazenil administration was found for SpO 2 , mean arterial pressure, I:E ratio, minute volume of ventilation (MV) and peak inspiratory pressure. There was a significant difference with flumazenil administration for the time to sternal recumbency, the time to the first attempt to rise and the total recovery time. There was no significant difference in total recovery score with flumazenil administration.Main limitations: Plasma levels of midazolam and flumazenil were not obtained.Conclusions: Flumazenil has a dose-dependent effect on MV and recovery time, which may make it useful in cases for which a prolonged anaesthetic recovery is undesirable.

Objective: To evaluate the effects of intra-articular (IA) mepivacaine administration prior to carpal arthroscopy on anesthetic drug requirements, blood pressure support, hemodynamic variables, and quality of recovery in horses. Study design: Experimental, analytical, cohort study. Sample population: Twenty-two horses (n = 11 horses/group). Methods: Horses were anesthetized by using the same protocol, but an IA injection of mepivacaine or saline was performed before carpal arthroscopy. End-tidal isoflurane concentration, heart rate, and mean arterial pressure were recorded at specific time points. Quality of recovery was scored by the anesthetist, who was unaware of group assignment. Data were analyzed by using two-way repeated-measures analysis of variance. Results: Mean arterial pressure was higher during joint distension in the control group compared with baseline (7% higher, P = .02) and with the treatment group (10% higher, P = .04). Heart rate was higher in the control group compared with the treatment group during joint distension (8% higher, P = .04) and chip removal (11% higher, P = .03). Heart rate was higher in the control group compared with baseline during chip removal (5.5% higher, P = .04). Two horses in the control group required additional ketamine vs none in the treatment group. Quality of recovery was not different between groups. Conclusion: Intra-articular mepivacaine resulted in fewer detectable reactions to surgical stimulation, with similar recovery scores and blood pressure support requirements. Clinical significance: Intra-articular anesthesia prior to arthroscopy can be used safely in the horse and should be considered as a part of balanced anesthetic protocols.

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This proof of principle study demonstrated that PAR, an indicator of PARP1 activity, can be identified in the equine species using immunoblot techniques, that equine PARP1 can be activated by H2 O2 -induced DNA damage, and that this activation can be inhibited by PARP1 enzyme inhibitors. The data suggest that the PARP1 pathway plays a role in the equine cellular response to oxidative DNA damage and supports its potential as a novel therapeutic target. Further research documenting an increase in PAR levels in vivo and the efficacy of PARP1 inhibitors in an equine intestinal ischemia-reperfusion model is needed.