Avaliação cardiorrespiratória de equinos sedados com xilazina ou detomidina

Abstract

Agonist drugs α-2 adrenergic receptors are used in veterinary medicine to promote sedation, analgesia and muscle relaxation. In horses with xylazine and detomidine are used in preanesthetic medication such as sedatives for procedures or surgeries in the standing position with the aid of locoregional anesthesia in analgesic infusions associated with general anesthesia for invasive procedures, or associated with dissociative drugs to anesthesia Overall the equine field. In the first study aimed to evaluate the sedative, gastrointestinal, cardiovascular and blood gas of xylazine and detomidine administered at different doses in horses effects. Eight horses, four males and four females, aged between five and 15 years, weighing 276.58±9.23 kg were used. The experimental design was randomized crossover using animals of six different occasions to receive: xylazine 0.5 mg/kg (X05), 1.0 mg/kg (X1), 1.5 mg/kg (X15); 20μg/kg detomidine (D20), 40 mg/kg (D40) and 60μg/kg (D60). The parameters evaluated were heart rate (HR); the electrocardiogram (ECG); respiratory frequency (f); systolic blood pressure (SBP), diastolic (DBP) and mean (MAP) by invasive method; Sedation (RAC); rectal temperature (T); intestinal motility (MI); blood gases and electrolytes. Some showed similar results to those previously reported with xylazine and detomidine as good sedation, significant reduction of HR and f, however, there was an increase in BP lasting with increasing dose of detomidine, as well as a reduction in intestinal motility for periods there are 180 minutes with the same drug. In the review of blood gas analysis showed a decrease in PaO 2 and increase in PaCO 2 in arterial blood, indicative of respiratory depression, increased bicarbonate ion (HCO 3 -) and base excess, however they remained within normal limits for the species. It follows that promotes more efficient detomidine sedation, however promotes a greater depression in cardiac system and intestinal motility compared with xylazine in horses. In the second study aimed to evaluate the sedative, cardiovascular and echodopplercardiographic effects of xylazine and detomidine in horses. Six horses, two males and four females, aged between five and 15 years, weighing 276.58 ± 9.23 kg were used . The animals used in randomized crossover design twice for receiving xylazine 1.0 mg/kg (GX) detomidine or 40 µg/kg (GD), administered intravenously. In addition to the parameters evaluated in the first phase of the study, also cardiac output (CO), cardiac index (CI), aortic diameter (AD), ejection fraction (FE) and fractional shortening (FS) by echocardiography were recorded. The results showed intense cardiorespiratory depression in animals that received detomidine, however with greater sedative effects compared to xylazine group. BP values showed an initial increase only in the detomidine group, lasting approximately 30 minutes and subsequent reduction of the values, without characterizing hypertension and hypotension. In echodopplercardiographic evaluation, the GD had major depression in ventricular function parameters, for the group GX and this review was efficient compared with values obtained in other studies by methods already established. It is concluded that detomidine sedation promotes more efficient compared to xylazine in horses, however the depressive effects on cardiovascular variables are evaluated by echocardiogram greatest method.