Just be mindful and compassionate -- not stupid and pitiful.
However you treat the mice will be good.
As all is mind; even small actions in altruism are litle steps toward wide oceanlike activities in equanimity with all beings.
It asks lots of power to break the pleasing protection kept under control by the guard dogs of prisonlike mind.
No any action is really bad or good or neutral intrinsically, and so those who want to be powerful and beyond bad and good, go on the vast path of liberation.