I don't know about dogs, but in ornithology they've lately begun reclassifying some species/subspecies based on relatively new DNA information. I'd imagine the same would go for other taxonomy systems--whereas in earlier years, one might have had to rely on boring old color and form. ;-)
a.k.a. Belgian tervuren. Developed in 1891 by the Belgian school of veterinary science under Professor Reul; an extremely close relative of the Groenendael, differing in the color of its coat. (Gosh, that hardly sounds like grounds for declaring it a separate breed...) According to Simon & Schuster's Guide to Dogs, 1980.