What type of dog is Ein from that anime series Space Cowboy Beebop?

If you've ever seen the popular anime series on cartoon network's adult swim, Cowboy Beebop, then you've noticed that the characters own a dog that accompanies them on their spaceship named Ein. What breed of dog is Ein? I'm seriously considering purchasing a dog for my niece, and this is the one she'd love. What breed is it please?