Changing death art

I have a question, you know the blood that's dropped when a unit dies, how would I go about changing this? Some units drop the generic red blood + bones, some drop green, some black, some none at all. Is the spawned animation set in the unit's model file itself, or an slk, txt file, or what? If it's in the model I guess I couldn't change it (multiplayer map, importing models would make it too big) Might be a question for the art forum...any pointers are appreciated :D

It is model specific