The purpose of this study was evaluation of magnesium sulfate effect in treatment of acute oleander intoxication in sheep. Eleven young native sheep randomly divided into 2 groups, 6 sheep being allocated to the treatment group and 5 served as controls. Sheep of both groups were dosed with a lethal dose of 110mg/kg body weight of dried oleander leaves. In sheep of treatment group, following development of ventricular arrhythmias, magnesium sulfate was slowly administered intravenously with dose rate of 100mg/kg body weight. Clinical signs of toxicosis were developed within 30 -40 minutes after dosing of the plant. Serial electrocardiography revealed various abnormalities and arrhythmias of cardiac rhythm in sheep of control group. Animals of control group died within 4.5 to 12 hours (median 8.5 hours) after receiving the toxic material. Administration of magnesium sulfate in sheep of treatment group suppressed ventricular arrhythmias to benign ones or normal sinus rhythm but its effect was transient and persisted for 3 to 3.5 hours. Second injection of magnesium had same effect but there was no considerable therapeutic effect after third injection of the drug. Sheep of treatment group died within 18 to 34 hours (median 24.5 hours) after receiving the oleander. Statistical analysis revealed a highly significant difference in survival time between the control and the treatment groups (p<0.004). The results suggested that magnesium sulfate can be used as a complementary therapeutic agent for treatment of acute oleander toxicosis in farm animals.

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