You need to rig mesh to horse skeleton. To not let animation show, just rig it all to a single bone (spine will do). Search for what rigging is and how to do it on the forum
Oh, and replace death animation with standing one in actions.txt
Thanks so much but i tried to rig it with the auto rigger? the mesh is going crazy an m&B is crashing too :p
and what do u mean spine bone? sorry im noob xDD