Research the Belgian Malinois. Bad ass dogs. Very smart, very agile, no hip problems, and they hit like a ton of bricks in bite work.

Make sure you know what you are getting into, though. They are dogs that like to work/play. I suggest a raw food diet, two raw chicken leg quarters a day, bone and all. Do some raw veggies as well. Crate training will be a plus.

For more help:

[link to leerburg.com]

Shalom...