Miniature dogs did not evolve naturally. They were bred by people as pets, to be companions and lap dogs. Due to their small size, they are sensitive to extremes of heat and cold and rely on human care to survive. Toys require minimal exercise and are long lived, affectionate and adaptable. They make an ideal pet in situations where keeping any other dog would seem impossible. Toys range in size from approximately one pound to eighteen pounds. They can be very highly strung and may not be suitable in households with boisterous young children.