Who am I? Figure this out. First answer?

corsola25 asked:

I am a popular dog in both UK and th U.S. I was breed for herding but I am now used as a guide, search and rescue, guarding, therapy, military dog. I used mostly in K9 unit for police work. I can come in White, Tan and Black, or all black.
First correct answer get 10 points
I know its pretty easy but just asking

Share and Enjoy: These icons link to social bookmarking sites where readers can share and discover new web pages.