A histopathologic study of Marek's disease (MD) lesions in slaughtered Broilers in Urmia slaughterhouse

The objective of this research was to study the macroscopic and histopathologic lesions of infected Broilers with Marek's disease in 6-10 weeds, although, it has been documented that MDV infection during these weeks, usually have no important histopathologic changes. From 12687 slaughtered broilers, 8 casesshowed MD changes after necropsy. There were skin lymphoid tumors in all 8 cases in 3 and spleen lesion liver and in 1 case in one. Changes were included visceral and cutaneous lymphoid tumors, containing accumulation of small and large lymphatic mononuclear cells and large amounts of pleomorphic tumor cells. No changes were found in nervous system, eye, bursa of fabricius and other organs. Results determined that MD can cause important histopathologic changes in such young broilers and makes considerable production loss.