Hey I have a beautiful 10 year old female jack russell terrier named Cassie. Like any typical Jack she loves chasing things like birds and mice. I currently have a budgie living in my room and I've managed to train Cass to leave the bird alone. the budgie is always in it's cage when Cassie is around. However I'm now considering getting a small animal like maybe rats or mice as pets, and I'm concerned I won't be able to train cassie not to attack them because of how they will smell and the movement she will see. Do you guys think this is possible? Despite the fact that she's an older dog, Cassie is still very intelligent and I'm always teaching her new things. Does anyone have any experience with this? thanks.