dog mating problem

Question
I have a shitzsu bitch and she is first time in heat.  My neighbour has a pitbull who she usually plays with. Now that she is in heat pitbull wants to mate with her but I think he is too big for her therefore, I burrowed my friends shitzsu to mate with her.  She would allow the pitbull come near her but not the shitzsu.  Please suggest a solution for this problem.

Thanks

Answer
Tanu, if this is your dogs first heat, she is TOO YOUNG to be bred. She is still a baby herself. I would suggest that you call and make an appointment to have her spayed. She cannot be spayed until she is finished with her heat cycle, which will be in a couple of weeks. So until then, you should keep her away from male dogs, and on a leash every time you take her outside. Dogs should not be mated until they are fully grown, and only if they are an exemplary example of the breed. You cannot know this unless you are active in showing the dog.

You are absolutely right that a pitbull is too large to mate with a female shih-tsu. If the mating didn't kill her, trying to whelp the puppies would.