...but, with that image in mind, Missy could be Sheltie/Rat Terrier, although, Shepherd was my first thought.

Yeah, about any dog that is not properly obedience trained will take off like a shot. They're silly and think that things HAVE to be more interesting elsewhere. I highly recommend getting her into an obedience class as soon as you can. Just to keep her from running off without you having any "grip" on her.

She's adorable!

Christi