Why can you not breed a male dog back to his daughter?

Most responsible breeders do not breed the bitch in the first estrous cycle (heat), although it is possible for them to become pregnant during that first season. Until a dog is around two years old, many genetic problems will not have shown up yet, like hip dysplasia, for example. You would need to wait to see that the bitch is healthy (e.g., that her hips are good when she fully matures), or have the proper testing done on the dogs to be mated to assure that you are not going to end up with a litter of puppies with potentially serious genetic disorders or conditions.

Females are able to conceive ("go into heat") only approximately every six to eight months. They usually have their first estrous ("season") at around six months, but some don't for as long as 14 months. As a rule of thumb, if she has not had an estrous cycle by the time she is 14 months old, you should have her examined by a veterinarian.

The decision to breed should be made with great care and only after you have learned much more about breeding, whelping, and caring for pregnant bitches and newborn puppies. In addition, before breeding, determine that the puppies will be wanted and will have good homes. A commitment to find good homes for all the new lives you will be creating must be made before even considering breeding any dogs.