RESUMO
Within a few consecutive days, 8 cases of lambs' mortality were reported from the Golestan National Park area [Golestan province]. According to the farmer's claims, the disease has occurred only in less than one year old lambs whose major feeding was free grazing in the oak rich areas and also collected and manually feeding with new and fresh buds of this tree. Ascites, hydrothorax, hydropericarditis, intestine, abomasum and mesenteric subserosal accumulation of fluid, and swelling of the kidney with cortex hemorrhage was observed in necropsy. Microscopic pathology revealed tubular and glomerular nephritis with tubular hyaline casts and mucosal necrosis with submucosal and serosal edema of GI specimens. Based on available epidemiological data, macro and microscopic pathology, oak poisoning is the most likely cause of mortality in this flock. It seems the major cause of mortality is the high sensitivity of these young animals and furthermore, the farmers insistence on feeding them the fresh buds of this tree