Cardiac Effects of an Alpha-2 Adrenergic Receptor Agonist in Dogs

Alpha-2 agonists are usually used in small animal anesthesia, sedation and as analgesic medicines. This medicines are used widely in combination with ketamine as pre-anesthesia medicines, although concerns about their cardiovascular complications prevent the complete acceptance in veterinary affairs. Researches on alpha-2 adrenergic receptor agonists and their clinical use are widespread. This study is performed to compare echocardiographic findings xylazine-ketamine in dog.The cardiovascular effects of α2 adrenoreceptor agonists have been generally described as dose dependent with the duration of effect clearly prolonged at higher doses. Low doses of romifidine (5 μg/ kg) appeared to have less pronoun ced cardiovascular effects than low doses of medetomidine, despite similar levels of sedation. Anticholinergic premedication has also been recommended with α2 agonists to prevent bradyarrhythmias and, potentially, the reduction in cardiac output produced by these agents (1-3). Xylazine was the first α2-adrenergic agonist to be used as a sedative and analgesic in veterinary practice. Concerns over the cardiodepressant and arrhythmogenic effects ofxylazine have prevented some veterinarians from embracing its use. Dysrhythmias characterized by heart block, premature ventricular depolarizations and tachycardia have been noted with anticholinergic and α2 agonist combinations, especially if the anticholinergic is administered concurrently rather than prior to the α2 agonist (1-3). This study was performed to describe the cardiac effects of xylasine-ketamine combination in dogs.Materials and MethodsFor this purpose, 5 healthy dogs at the age of 1-2 years were prepared and were examined clinically and their clinical health was confirmed. Then 5mg ketamine and 1.1mg xylazine was injected intravenously and in fasting mode per each kilogram of body weight.Echocardiography measurement parameters included: the size of the left ventricle during systole (LVDs), the size of the left ventricle during diastole (LVDd), heart rate (HD) and short fraction. All The data were analysed by statistical analysis software SPSS.ResultsAfter muscular injection of ketamine-dexmedetomidine, LVDd and LVDs increased significantly as well, HR didn’t change a lot but FS had great reduction. Muscular injection of ketamine-xylazine reduces heart rate and cardiac output while muscular injection of ketamine-dexmedetomidine only reduces the cardiac output.