Estudo comparativo da dexmedetomidina injetável e por meio da farmacopuntura em bezerros

Abstract

In the routine of ruminants, the performance of clinical and surgical procedures in calves is frequently observed and there is a need to promote sedation to avoid stress, pain and errors; therefore, sedative protocols that provide greater safety to the patient are of great importance for the area. Alpha-2 adrenergic agonists are the most commonly used drugs for sedation in calves, with dexmedetomidine described as being more specific for alpha-2 receptors, which contributes to a lower occurrence of adverse effects. Pharmacopuncture is performed with the administration of subdoses of drugs or medicinal extracts at certain acupuncture points in order to reduce doses and potentiate the drug, offering a safer alternative. In the present study, the clinical and sedative effects of intramuscular (IM), subcutaneous (SC) and Yin tang (YT) acupoint dexmedetomidine were evaluated. For this purpose, six Girolando animals were used, 3 males and 3 females, between 6 and 10 months of age, submitted to five experimental protocols, respecting the one-week interval between treatments: 4 µg/kg of dexmedetomidine IM, 0 .8µg/kg of dexmedetomidine YT (YT 1/5), 0.8µg/kg of dexmedetomidine SC (SC 1/5), 0.4µg/kg of dexmedetomidine YT (YT 1/10) and 0.4µg/kg of dexmedetomidine SC (SC 1/10). The following parameters were measured before (M0) and after (M20, M40, M60, onwards) of drug administration: respiratory rate (f), heart rate (HR), systolic blood pressure (SBP), rectal temperature (RT), ruminal movements (MR), hematocrit (HT), blood glucose (GL), P-R interval and the degree of sedation. Data were tabulated and submitted to statistical analysis. There was no significant change in f, SBP, P-R interval, TR and HT between groups and over time. Heart rate decreased between 20 and 120 minutes in the IM group, and differed between the IM group and YT 1/5 and 1/10 in M20 and between IM and YT 1/5 groups in M40. There was a decrease in RM between 20 and 80 minutes in the IM group, which presented lower values when compared to the other groups in M40 and in relation to YT 1/5 in M60. GL increased in the IM group at all experimental times. The IM group presented behavioral changes that lasted from M20 to M120, while eyeball rotation and response to sound stimulus differed from baseline only in M20. There was a decrease in the response to sound stimuli in the YT 1/5 group at M20. Pharmacopuncture with 1/5 of the IM dose of dexmedetomine in the Yin tang acupoint promoted mild reassurance. Dexmedetomidine intramuscularly at a dose of 4µg/kg provided moderate sedation for up to two hours in calves, without significant clinical implications for the animals, and may be indicated for procedures that require recumbency.