Evaluation of blink parameters obtained by electrical stimulation in general anaesthetised dogs

The aim of this study was to evaluate the relationship between the blink reflex and general anesthesia in dogs. Dogs brought for castration or ovariohysterectomy without any other problems were included in the study. In dogs anesthetized for the surgical procedure, anesthesia was kept constant at 2.9 MAC. Following the procedure, the supramaximal electrical stimulation was applied to the supraorbital nerve for every 0.1 MAC value decline, beginning at 2.9 end tidal MAC, and blink parameters were recorded from both orbicularis oculi muscles. The latency, amplitude, duration, and differential latency values of blink parameters obtained independently of MAC under general anesthesia were revealed. At the same time, it was also determined which blink parameters were obtained in which MAC value range. Previous studies have shown that the R2 and RC are highly affected by the level of consciousness, and the RC disappears under general anaesthesia. The R2 value was most commonly obtained between 1.1 and 1.0 MAC, but the dogs did not respond to any stimulus when the R2 value was obtained. However, since previous studies have shown that the level of consciousness affects R2 values, it was assumed that surgical anesthesia may have disappeared in the MAC ranges where this value was measured. The MAC value from which the RC value was obtained was found to be 0.88, and it was assumed that it could be accepted as the average MAC value at which the effect of general anesthesia was eliminated for dogs.