I'm trying to figure out this movie I saw..?

I can't remember the name of it...but all I remember was that the main character was a woman and she was like a tv reporter type person..and she went to this lab that did experiments on animals...and she found a rottweiler..but this was a super dog..he had like DNA from a bunch of different animals..like...a cheetah for speed or something...and she lets him loose...and he saves her from a guy who tried to like her..and he kills him..and the dog hates her bf...and I think kills her bf...but I think thats all I got around to....does anyone know this movie????