The objective of this study was to evaluate the analgesic effect of magnesium sulphate with special reference to its recommended doses for spinal analgesia in donkey and its effect on animals’ vital parameters (pulse and respiratory rates, body temperature). Twenty four clinically healthy donkeys of both sexes were divided randomly into a subarachnoid group (group I=15 animals) and a control group (group II=9 animals). Animals in group I were subdivided into three equal subgroups, Ia, Ib and Ic and recieved magnesium sulphate intrathecally in doses of 1, 2 and 4 ml respectively. Those in group II were subdivided also into three equal subgroups IIa, IIb and IIc and recieved normal saline intrathecally in doses of 1, 2 and 4 ml respectively. All animals were put under clinical observation. Animal analgesia was monitored at various standard dermatomes by pinching a fold of skin by an artery forceps. Vital signs monitoring included pulse and respiratory rates, body temperature, hind limb as well as the desensitized areas. Lumbosacral IT injection of 1 ml, 2 ml and 4 ml magnesium sulphate resulted in analgesia that started after 1-2min. from the end of injection and lasted for 14.32+3.51, 46.60+10.69 and 78.20+9.83 min. respectively. Analgesia involved the flank area in the subgroup Ia (1 ml) and extended in both subgroups Ib (2 ml) and Ic (4 ml) to include the gluteal region, tail, perineum, udder or scrotum, lateral aspect of the thigh till the level of the stifle joint distally and extended cranially to the level of the first rib. Recumbancy occurred only in 3 animals in subgroup Ib and 2 animals in subgroup Ic. Physiological changes were within normal limits throughout the whole experimental time. Intrathecal MgSO4 10% has an analgesic effect in donkeys with minimal physiological changes but 2-4 ml are needed for extended analgesia, these data must be checked under surgical conditions.
Ahmed Ibrahim, Ahmed S. Saleh and Mohammed M. A. Semika