I have a big ol' black Lab.
Your Jack Russels are in for a run for their money.

Lab puppies are very active ....... ummm, VERY active!
They are incredible dogs.

They are very curious, very playful and very sweet. They take a little longer to settle down than most puppies - they seem to out grow that almost hyper-active behavior by the time they are 2, in my case, 4.

They just like to go, go, go!
They are extremely intelligent and easy to train. Just make sure you give her lots of activities to keep her busy. Long walks are great for Labs.
Mine was very mouthy too. He loved to chew, bite or mouth things. A "Kong" toy filled with peanut butter or cheese, some raw carrots, pears and apples helped my dog with that a lot.
Crate training is good for any puppy, but I'm especially glad we did so with my Lab. He only needed the crate until he was 6 months old, but I'm sure it kept him out of trouble when we weren't home. He was easy as anything to housebreak. When out of the crate we kept him confined to the living room (well, I took him to bed with me at night, I mean when he was playing). He taught himself how to go to the door and cry to go out.
All in all, I've had a wonderful experience with him. I adore him, his temprement, his gentleness and his sense of humor. I'm glad he's mine.
I wish you all the best with her and hope you have the same wonderful experience with your Lab that I've had with mine.
