Dog Birth Control Pill
Female dog in heat can mate accidentally

Is it possible to give my dog a birth control pill? Yes. There are ways to delay the start of a period, and to prevent this happening when the first symptoms arises. Talk with your veterinarian about this and other alternatives. Methods may be elected according to circumstances. If you are planning your vacations, you won't like taking your female dog in these conditions, and a canine residence will refuse to accept her; then a hormonal treatment, based on pills and shots, will be needed. For this purpose there are a lot of choices, for more information contact your veterinarian, or a dog clinic. These treatments won't prevent your dog having healthy puppies in her heat. These artificial hormones act like the natural progesterone hormone, impeding secretion of another hormone, the estrogen, needed to start estro phase.

My female dog was mounted by my neighbor's dog