I adopted a female dog from a shelter a few months ago. I was not planning on having any puppies at all. When I adopted her I was told she was three months old. About two months after we brought her home she went into heat. I only knew this because my husbands grandmother breeds english cocker spaniels and I asked her what was going on. We were going to spay her when she was six months old. We took her to get some of her shots and they did a physical and told us she was at least a year and half old. We were shocked because she is a small dog. We figured it must be the jack russell in her. Well a little over a month and ago she started to get enlarged teats, and her back side is swollen, but there is no change in her stomach size at all. However her teats have continued to grow. I took her to a vet to be looked at and they said she looks pregnant, but still no large tummy. I am told that she may not show until she is about to give birth. Is there any other reason for a dog to look so pregnant and not be?