Med. Weter. 74 (3), 187-192, 2018

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Effect of xylazine, medetomidine and dexmedetomidine on cardiac conduction in pigs
The majority of anaesthetics used in studies regarding heart arrhythmias may affect the cardiac conduction system, thus influencing the results. In veterinary medicine, xylazine, medetomidine and dexmedetomidine are commonly used for premedication in laboratory and companion animals. To date, there have been no studies assessing the effect of these substances on the cardiac conduction system. The aim of this study was to assess the effect of xylazine, medetomidine and dexmedetomidine on the parameters of the cardiac conduction system in pigs. The study was carried out on 18 Great White Polish male pigs weighing from 21 to 40 kg. The animals were divided into three equal groups. The animals from the first group received xylazine at a dose of 2 mg/kg i.v.; those from the second group received medetomidine at 40 mcg/kg i.v.; and those from the third group received dexmedetomidine at 10 mcg/kg i.v. The electrophysiological activity of the heart was analysed using an invasive electrophysiological study (EPS). During the EPS, a decrease in the heart rate after substance administration was observed in all animals, but there were no statistically significant differences in the cardiac conduction parameters. A pro-arrhythmic effect of xylazine was observed, but no statistically significant changes in the EPS parameters were noted. Our results indicate that medetomidine and dexmedetomidine may be used as standard premedication drugs in electrophysiological studies in pigs. Their use may facilitate animal preparation procedures without affecting study results..
Key words: xylazine, medetomidine, dexmedetomidine, EPS, pigs