Comparação do efeito analgésico entre Morfina, Tramadol e Buprenorfina em gatas submetidas a ovariossalpingo-histerectomia eletiva

Abstract

The ovariohysterectomy (OHE) is the most common surgery realized in the small animals hospitals in order to control animal population and to prevent future problems of reproductive order. This surgical procedure has a moderate degree of pain and requires analgesic treatment. Postoperative pain, when not correctly diagnosed and treated, instead of being a mechanism of natural defense, becomes harmful and promote systemic alterations that delays the recovery of the patient. The objective of this study was to compare the analgesic effect in the trans and postoperative period between morphine, tramadol and buprenorphine, that were given to cats prior having OHE. In this study, 30 cats were used, with no specific breed and healthy. The animals were distributed in three groups of 10 animals. Group M received daily pre-anesthesic medication (PAM), acepromazine maleate (0.05 mg/kg) and morphine sulfate (0.2 mg/kg) intramuscularly (IM). Group T received acepromazine (0.05 mg/kg) and Tramadol (2.0 mg/kg) IM and Group B received acepromazine in the same dose and buprenorphine (0.01 mg/Kg) IM. After 20 min of applying PAM, the animals received an induction of the anesthesic thiopental 2.5% in the dose of 12.5 mg/kg intravenously. The animals were kept with isoflurane diluted in 100% oxygen through the universal vaporizer, connected to a circuit of Mapleson D (Baraka). The evaluation of pain and sedation was done by one person who observed for all the animals, and he did not know the treatment used (double blind). The evaluation times were: daily presurgical; 10 min, 20 min and 30 min of surgery and 1, 2, 4 and 6 hours after surgery. The subjective evaluation of pain was done through a visual analogue scales (VAS) and through a descriptive scale before and after the surgery. The measurements of cardiac frequency (FC), respiratory frequency (FR), temperature (Temp), plasma glucose (GL), time of capillary perfusion (TPC) and analysis of mucosa were made moments before, during, and after the surgery. The gauging of the systolic arterial pressure (PAS) and saturation of oxygen hemoglobin (SpO2) were made only during the surgical procedure. The comparison of the objective and subjective parameters between the three groups was done by using the Analysis of Variance of Kruskal-Wallis, followed of the Mann-Whitney test, whenever were significant differences between the treatments (p< 0.05). Inside of each group, the Analysis of Variance of Friedman was used for the comparisons between the diverse moments, followed by the test of Wilcoxon for the identification of the different moments (p< 0.05). Animals of the buprenorfina group (B) were more sedate in all the evaluated moments, followed by the group morphine (M) and finally the group tramadol (T). In the evaluation of pain for the VAS, the group tramadol demonstrated a lesser degree of pain in the first the 2 hours, followed by the groups with morphine and buprenorphine. In the evaluation of pain for the descriptive scale, tramadol presented better analgesic effect at the times 2, 4, and 6 hours. The values of cardiac frequency remained relatively constant during the surgical procedure, only being different at the times 4 and 6 hours where the buprenorphine group presented higher values. In the present study, the reduction of the FR was more accentuated in the morphine group. Difference in the PAS between the groups was not observed. The buprenorphine group presented higher values of glucose at the moment 6 hours. In this study, the body temperature did not differ between the groups in the pre or postoperative moments. With this study, it can be concluded that tramadol, in the given dose and regimen, is more efficient than the morphine and buprenorphine in controlling of postoperative pain of OHE in cats, without signs of collateral effect.