Pumpkin may help her out, it may not work immediately though. Since she is petite, I would try giving a small portion of canned pumpkin (just plain pumpkin, not the one with spices added). One to two teaspoons added to her food or licked off a finger may help get things moving. Milk may help as well since most dogs are lactose intolerant, however this may lead to the opposite problem if given too much. However, if she does not get relief and appears in pain or discomfort she may need a vet to manually extract her hardened stools. I hope she did not eat any raw hide bones lately, or this may be sign of an obstruction. Best wishes!