Oleanders are drought-tolerant evergreen plants of the Family Apocynaceae that originated from Mediterranean countries. Two common oleanders are Nerium oleander and Thevetia peruviana (yellow oleander). In the present study, we aimed at evaluating the pathological effects and serum biochemical changes of oleander in sheep. Seven male native Iranian sheep (8-12 month) were randomly divided into two groups, 5 treatment and 2 controls. Sheep of both groups were administrated the lethal dose of 110 mg/kg body weight of dried oleander leaves. Animal in control group died within 41 to 56 hours after dosing of the plant. All sheep in treatment group, one hour after dosing with oleander leaves took activated charcoal (5gr/kg, single dose) via stomach tube. Immediately after development of ventricular premature arrhythmias, 5mg propranolol hydrochloride was administrated intravenously in repeated doses. Three sheep in treatment group did not show any dysrrhythmia and were lived and did not receive any drugs. One sheep of treatment group took the propranolol hydrochloride in regime but was died after 80 hours. Propranolol hydrochloride in last sheep of treatment group changed ventricular arrhythmias to sinus rhythm. This sheep was lived after taking the antidysrrhythmia drugs. In these animals, the main lesions were hepatonephropathy and varying degrees of coagulative necrosis of cardiac muscle cells and necrosis of hepatocytes and necrosis of tubular epithelium in kidneys and were accompanied by significant increases in concentration of glucose, BUN and Bilirubin after administration of Nerium oleander in treatments animal.
