Lily, our female, is around 5 lbs. and Buddy, our male, is not quite 4 lbs. Yes, I definetly want the vet to do an X-Ray to make sure that she can have the puppies naturally. It is sooo hard because we want for both Rosie and Lily to be able to experience having a litter of pups. If Lily is pregnant and ends up having a C-Section I will ask for them to spay her as well. Good Advice!!