Among domestic varieties, dogs tend to be bigger than cats, but in the wild, the opposite is true.
Among common house pets, cats can be just as big as dogs, while in nature, dogs are usually smaller than cats.
Though some dogs are smaller than cats, this is usually not the case, neither among pets, nor in the wild.
Dogs and cats that live with people are, on the average, rather smaller than those that live in the wild.
Wild dogs and cats can grow to great sizes; much larger, in fact, than either animal is likely to get as a pet.
Wild cats are normally larger than wild dogs, but as far as pets are concerned, cats are usually smaller.