For this kind of accuracy, you'd consider the first time a dog mates during her heat cycle as day one. If you know when your dog's heat cycle ended, you can narrow things down even further ...

Unspayed female dogs can have their first heat cycle anywhere between 6 and 15 months of age. During heat, which happens every six months or so and lasts a few weeks, your dog can get pregnant.

Spaying a female pet can help prevent uterine infections and ovarian cancer, while neutering a male pet can reduce the chance ...