Call your vet. One thing that I recently learned from my sister who got a kitten. Dogs only go in heat a couple times each year; as puppies they may not go for the first year at all. Kittens start around 6 to 8 weeks and keep on every so many weeks; it drove my sister crazy; her kitten would only want attention when she was in heat so it was easy to tell when she was in which seemed like most of the time.