Effects of medetomidine/ketamine and xylazine/ketamine anesthesia and their reversal by atipamezole on ocular parameters and monitored anesthesia care in cats

Abstract

The aim of this study was to investigate the impact of the general anesthetic drug ketamine and premedication agents medetomidine and xylazine, and their reversal by atipamezole, on monitored anesthesia care values and ocular parameters such as intraocular pressure, horizontal pupillar diameter, and Schirmer tear test in cats. A randomized, single-blinded study was conducted. Twenty intact female cats (weiging between 2.2 and 3.6 kg, and 0.5 to 5.5 years of age) referred for ovariohysterectomy (OHE) procedure by the owners at regular intervals over 4 months were included in the study. The cats were randomly divided into two groups containing 10 animals in each group. The cats were premedicated with medetomidine 80 µg/kg intramuscular in group 1 while the cats in the 2nd group were premedicated with xylazine hydrochloride 2 mg/kg intramuscular. After the OHE procedure was ended, anesthesia regimes were reversed by using atipamezole 200 µg/kg intramuscularly. Monitoring of respiration rate, heart rate, mean arterial pressure, peripheral arterial oxygen saturation, and body temperature were conducted using a patient monitor at T0, T1, T2, T3, and T4 time points. Both groups showed declines in intraocular pressure and increases in horizontal pupil diameter after anesthesia induction (T0 vs. T1, all, P<0.05); however, the chancing and recovery pattern of intraocular pressure and horizontal pupil diameter showed intergroup difference. In conclusion, xylazine/ketamine is more effective than medetomidine/ketamine in attenuating the intraocular pressure, increasing the horizontal pupil diameter, and alteration the monitored anesthesia care response in the general anesthesia.