Sacrificing an animal in dreams suggests that we are aware that our lower, more basic instincts can be given up in favour of spiritual power. We have to be prepared to recognize our own human fallibility, but to give up extravagance.
A sacrificial altar may appear, or it may just be a question of killing and cooking an animal ritualistically.
If the animal is willing to be sacrificed, then we are ready to transmute instinct into spiritual energy.
If the animal is a hare or a rabbit, the symbolism is that of rebirth.