1. Pre-implantation stage (Day 0-4):
- Fertilization occurs when sperm meets the egg in the fallopian tubes.
- The fertilized egg (zygote) undergoes cell division as it travels through the fallopian tubes toward the uterus.
2. Implantation stage (Day 5-15):
- The developing embryo reaches the uterus and begins to implant into the uterine wall.
- The embryo forms an outer layer (trophoblast) that attaches to the uterine lining, while the inner cell mass develops into the fetus and embryonic structures.
3. Embryonic stage (Day 16-35):
- Rapid development of the fetus occurs during this stage.
- Major organ systems, including the heart, brain, limbs, and digestive tract, begin to form.
- The fetus becomes recognizable as a dog with distinct features.
4. Fetal stage (Day 36-63):
- The fetus continues to grow rapidly, and its organs become more complex and functional.
- The fur begins to develop, and the fetus becomes covered in a fine layer of hair.
- The bones harden, and the fetus starts to move and make small kicks.
- The fetus is fully developed and ready for birth by the end of this stage.
5. Birth (Parturition) (Day 63-68):
- Labor begins with uterine contractions, causing the cervix to dilate.
- The mother dog gives birth to puppies, usually head-first, one at a time.
- The mother will also expel placentas after each puppy is born.
6. Postpartum stage (After birth):
- The mother dog enters a postpartum period characterized by hormonal changes and milk production.
- The puppies begin to nurse and rely on their mother's milk for nourishment.
- The mother dog will care for and protect the puppies until they are strong enough to become independent.
It is important to note that the exact timing of each stage may vary slightly among individual dogs and breeds. If you have any concerns or questions about your dog's pregnancy, it is best to consult with a veterinarian for proper care and guidance.