Hey Alan, you can take her to the vet and get a shot that will abort her in case one did breed her. This will bring her back into heat again but you will have to make sure that she cant get out this time. This will allow you to breed her when you want to what you want. This is what i would do, so that to ensure she is bred to the dog you want. Just my .02 worth.
Hey Spencer.
I was wondering about what kind of time frame you have with the shot you refer to. How long do you have to give a dog that shot after you think she might have been bred?
Not sure on the time frame, but i would do it ASAP. I had to have it done with my German Shepherd back in college, but thats been years ago!