0 s . ▁Though ▁staff ▁initially ▁argued ▁that ▁the ▁animals ' ▁odd ▁appearance ▁was ▁due ▁to ▁capt ivity ▁and ▁di et , ▁it ▁was ▁later ▁decided ▁to ▁e uth an ise ▁them . ▁ ▁In ▁ 2 0 1 8 , ▁a ▁study ▁compared ▁the ▁sequences ▁of ▁ 6 1 , 0 0 0 ▁single - n uc le ot ide ▁polym orph isms ▁( mut ations ) ▁taken ▁from ▁across ▁the ▁gen ome ▁of ▁grey ▁wol ves . ▁The ▁study ▁indicated ▁that ▁there ▁exists ▁individual ▁wol ves ▁of ▁dog - w olf ▁ancest ry ▁in ▁most ▁of ▁the ▁w olf ▁populations ▁of ▁E uras ia , ▁but ▁less ▁so ▁in ▁North ▁America . ▁The ▁ad mi xture ▁has ▁been ▁occurr ing ▁across ▁different ▁time ▁scales ▁and ▁was ▁not ▁a ▁recent ▁event . ▁Low - level ▁ad mi xture ▁did ▁not ▁reduce ▁the ▁w olf ▁distinct iveness . ▁ ▁In ▁ 2 0 1 9 , ▁in ▁the ▁Os og ovo ▁mountain ous ▁region ▁along ▁the ▁border ▁between ▁Bulg aria ▁and ▁North ▁Mac ed onia ▁a ▁put ative ▁grey ▁w olf ▁was ▁recorded ▁by ▁camera ▁to ▁be ▁living ▁with ▁a ▁pack ▁of ▁ 1 0 ▁fer al ▁dogs , ▁and ▁by ▁its ▁behaviour ▁and ▁phen ot ype ▁was ▁assumed ▁to ▁be ▁a ▁w olf - dog ▁hy brid . ▁ ▁Bre ed - specific ▁legisl ation ▁ ▁The ▁w olf dog ▁has ▁been ▁the ▁center ▁of ▁controvers y ▁for ▁much ▁of ▁its ▁history , ▁and ▁most ▁bre ed - specific ▁legisl ation ▁is