Avaliação dos efeitos clínicos e sedativos da dexmedetomidina intramuscular, subcutânea e no acuponto yin tang em bezerros

Abstract

α-2 adrenergic agonists are the main sedatives used in ruminant medicine, and dexmedetomidine is described as the most selective and safe among the drugs in this group. Pharmacopuncture has become an alternative in sedation protocols for large animals, since it aims through subdoses to achieve a similar effect of the conventional dose of the drug and the reduction of undesirable effects. Thus, the present study aimed to evaluate the clinical and sedative effects of dexmedetomidine intramuscularly, subcutaneously and in the Yin Tang acupoint in calves. For this, six animals were used, three males and three females of the girolando breed, submitted to three experimental protocols: intramuscular dexmedetomidine at a dose of 4µg/kg (DEX-IM); subcutaneous dexmedetomidine at a dose of 0.4µg/kg (DEX-SC) and dexmedetomidine in the Yin Tang acupoint also at a dose of 0.4µg/kg (DEX-YT). Parameters were evaluated at baseline (M0) and every 20 minutes thereafter (M20, M40, onwards), respiratory rate (f), heart rate (HR), systolic blood pressure (SBP), temperature rectal (TR), ruminal movements (RM), hematocrit (HT), glycemia (GL) and degree of sedation. Data were submitted to analysis and statistics. The f remained stable in the DEX-YT group, and showed a tendency to decrease in the DEX-IM and DEX-SC groups, however there was no statistical difference between the times in the three groups. SBP showed no statistical difference between the groups or over time, however, it showed a tendency to increase in the DEX-IM group. HR decreased in the DEX-IM group, while in the DEX-SC and DEX-YT groups it remained stable. RM decreased in the DEX-IM group, which did not occur in the DEX-SC and DEX-YT groups. HT and TR showed no statistical difference between groups or over time. GL showed a significant increase in the DEX-IM group, however, in the DEX-SC and DEX-YT groups there was no increase. Regarding the degree of sedation, only the animals in the DEX IM group showed behavioral changes that lasted for up to 120 minutes. Dexmedetomidine, at a dose of 4µg/kg administered by the intramuscular route, causes moderate sedation in dairy calves for up to 120 minutes, without presenting clinical complications. The dose of 0.4 μg/kg administered subcutaneously and in the Yin Tang acupoint did not promote sedation in these animals. The dose of 4µg/kg of dexmedetomidine may be indicated for short-term procedures in healthy animals.