For the record, I love dogs, especially the history behind them. They were mankind's first genetic creations. They are in no way devolved from wolves. The fact is, dogs have a greater range of traits and mutations than any other animal, period. Each breed exists for a reason, and was bred for that purpose. Some are just supposed to be pretty, yes, but most were bred to either be faster, stronger, larger, smaller, friendlier, better at tracking, better at killing, smarter, or some other trait (or colmbination). Almost any breed can mate with almost any other breed and they can even be bred with wolves, dingos, coyotes, and most other wild dogs and STILL produce fertile offspring! That's amazing, considering ligers, mules, and almost every other cross-species offspring is completely sterile.
In short, the domesticated dog is actually the ultimate animal as far as evolution is concerned.