One-Week Development in Pregnant Dogs

The full gestation period for a dog is only 63 days on average. Twenty-eight days after conception, the fetus will start to resemble a puppy. Mitosis, or the process of cell division, leading to the development of the fetus, begins with fertilization. One week after mating, the process of cell division is almost complete.

  1. Fertilization

    • A dog's pregnancy begins with fertilization, the physical union of a sperm cell and an ovum. Fertilization occurs five days after mating. A chemical reaction curing fertilization prevents other sperm from imbedding in the egg. The cell resulting from the union is called a zygote.

    Cell Division

    • About 12 hours after fertilization, the zygotes begin cell division, repeating every 12 hours. The organisms continue to grow and divide, moving toward the dog's uterus. Even in this first week, the embryos are fairly resistant to external interference. When the cells reach the uterus, approximately 10 days after mating, they have entered the active embryo stage.

    Embryo Implantation

    • After two weeks, the embryos implant in the uterine wall and the placentas start to develop. At this point, the embryos are termed fetuses. Fetuses are not detectable on abdominal palpation until 21 to 25 days of pregnancy.

    The Mother Dog in Week One

    • Some pregnant dogs show no sign of pregnancy in the first week. Others experience morning sickness or personality changes. During the first week, the pregnant mother maintains a normal diet and exercise regime as the cell development going on inside requires little from her.