EEG Recordings in Anesthetized Rabbits: Comparison of Ketamine-Midazolam and Telazol With or Without Xylazine.

Electroencephalographic (EEG) recordings were performed on five New Zealand White rabbits anesthetized by using four intramuscular drug combinations: 1) ketamine (30 mg/kg) and midazolam (0.2 mg/kg), 2) ketamine (30 mg/kg), midazolam (0.2 mg/kg), and xylazine (3 mg/kg), 3) Telazol (20 mg/kg), and 4) Telazol (20 mg/kg) and xylazine (3 mg/kg). All four combinations were administered randomly to each rabbit. To evaluate anesthesia depth, response to toe pinch and various measurements from the recordings were assessed before and after injection. For each EEG recorded epoch, b/d ratios and the spectral edge frequencies (SEF) at 80% and 95% were measured. Results show that after injection of combinations without xylazine, b/d ratios and SEFs decreased only slightly; concurrently the withdrawal reflex remained present. Adding xylazine decreased the b/d ratios (p, 0.001) and the SEFs at 80% (p, 0.001) and 95% (p, 0.001). No withdrawal reflex was observed for 30 min after injection of ketamine-midazolam-xylazine and for 60 min after administration of Telazol-xylazine. Therefore, EEGs may be used to evaluate depth of anesthesia when using injectable drug combinations in rabbits.Abstract>