Small dogs or lap dogs or comforters as they were once called have a very extensive history, encompassing several thousand years. Small breeds were often kept by nobility and given as presents to royal figures. It was also thought that small breeds were good for ones health. The Pekingees, pug and King Charles Cavalier Spaniel are three examples.
Many dog owners have a preference for small dogs over larger breeds, and for many different reasons. However, by virtue of their diminutive size, these dogs are much more affordable to keep, need less exercise in relation to larger breeds in general, and are simple to transport for example.
Many owners of larger dogs, and often those thinking of caring for a new dogs avoid smaller breeds, because of the perceived differences in their behaviour, in relation to larger dogs. It is thought, and wrongly of course, that smaller dogs are by nature, yappy, aggressive, possessive, over protective and demanding,, and so on.