Did you know that there are more than 150 recognized dog breeds but only 41 documented cat breeds? There is much more variety of temperament, facial features, body shapes and physical abilities in dogs than those in cats. Dogs can weight between 5 and 180 pounds whereas cats' weight usually ranges from 6 to 20 pounds with overall similar size, shape and look. Why is there so much more variety in dogs compared to cats?
Dogs started their human relationship thousands of years ago. They were domesticated to help humans in numerous jobs and work such as hunting, herding, hauling sleds and so forth. Throughout the years, humans cross bred various dog pedigree breeds and rendered many new breeds to provide better performance for human needs.
Cats, on the other hand, came to humans' life a bit later than dogs. Their role was primarily as a mouser or a companion. They were assigned much fewer tasks than dogs, thus not many cat owners were compelled to tweak the breeding of cats. That explains why cats have far less variety and more similarity than their canine counterparts.