What age can a male dog impregnate a female?
Puberty for a male dog is usually around 6 months, generally it is advised to keep an unneutered dog more than 4 months separated from a female in heat, just in case. Dogs between puberty and full sexual maturity can impregnate a female, though they do not reach full fertility until around 18 months. I would keep them apart until she’s done with her heat just to be on the safe side.