I would say she's a good mix, all dog. If pressed I would say "She's got the coloring of a Swiss Mountain Dog or a tri-color Aussie (see http://DogoftheDay.com/archive/2008/March/13.html), the build of a Lab, but not the height, maybe she's a Beagle (to account for her shorter height)/Lab/Aussie mix.

Swissies are much, much bigger dogs, so I doubt that's in her mix, or Rottie, as she just doesn't have the height for either breed. Also, Rottie is on some breed watch lists, so I'd avoid that unless you were sure anyway.