What happens next?

How to know if a male dog is fertile
Make sure that your dog is old enough to breed.
A male dog that is too young will not be able to reproduce. A male dog usually reaches sexual maturity when they are over a year old, however they usually begin puberty when they are six months to eight months old.
They can impregnate a female dog from the point of puberty on. If you want to use your dog for breeding when it is at its maximum fertility, wait until it is at least a year and a half old.