Well there are many ways to deal with Rotting Cow and throwing is just one of them:
So far only Decoy throws it back.
Skellige has option to kill Rotting Cow. (Holger Blackhand, Brokvar Archers etc)
Northern Realms can turn units to gold to avoid it.
Monsters have several units which can simply consume Rotting Cow.
Epidemic can take it down since it is a 1 strength unit.
You could also choose to lock the Rotten Cow which will prevent it from finishing the job.
Play Pavetta for double epidemic effect.
Vilgefortz can burn it for advantage.
Suboptimally you could choose to use Tremors, Yennefer Chironex, Alzur's Thunder or Lacerate.
Perhaps it is not exactly throwing back but cards like Udalryk(by chance) and Caretaker(guaranteed) can play Rot Tosser from graveyard against Nilfgaard.