Week One

• During the first week of puppy fetal development, the embryo is practically impervious to outside interference. The dog carrying the fetus may feel morning sickness and undergo various personality changes. During this and subsequent weeks, the dog should not be given any live vaccines or treatments containing insecticides.
  
  

Week Two

• In the second week of puppy fetal development, the fetus advances from a four celled embryo to a 64 celled embryo. It is also during the second week that the embryo enters into the uterus.
  
  

Week Three

• During week three, the embryo attaches itself to the uterus. Pregnant dogs may still be feeling morning sickness and experiencing personality changes during this time.
  
  

Week Four

• Several changes occur in the fourth week of fetal development. The fetus increases in growth between five and ten millimeters; the fetus develops a spinal cord and eyes, and the face takes shape. The internal organs begin to develop and it is during this time that embryos are at the most danger of developing birth defects. Week four is the best time to take the dog to a veterinarian and have a professional feel for the puppies. The dog may experience vaginal discharge, and mammary glands will begin to develop. Owners should begin to limit their dog's strenuous activity such as jumping or extensive running. Add protein to the dog's diet in the form of a quarter cup of cottage cheese or a hard boiled egg every other day.
  
  

Week Five

• During the fifth week of development, fetuses develop toes, claws and whisker buds. Fetuses begin to resemble dogs, and their gender can be discovered through an ultrasound. Due to uterine fluid, feeling for the fetuses (palpitation) is no longer possible. Fetal eyelids develop and close over the eyes. The fetuses grow another 12 millimeters, and their internal organs finish developing. At this point, the fetuses are once again practically impervious to outside interference. The dog carrying the fetuses gains weight and becomes noticeably pregnant. Owners should increase the amount of food given to the dog and add a multi-vitamin to the dog's diet daily.
  
  

Week Six

• During the sixth week of puppy fetal gestation, the skin pigment is developed. The fetal heartbeat can be detected with a stethoscope, and the fetuses should weigh approximately six grams and measure 45 millimeters in length. The pregnant dog's nipples will enlarge and darken, and it's abdomen will continue to swell. Owners should begin giving the dog cottage cheese or a hard boiled egg every day, and increase the dog's overall food intake. The expectant canine should also being sleeping in its whelping (birthing) box.
  
  

Week's Seven through Nine

• During week seven, the fetuses will continue to develop and the dog will continue to increase in size. Additionally, the dog's abdominal hair will begin to shed. After week eight, the puppies are able to be born safely. While the mother is resting, the puppy fetuses can be seen jostling around. During the ninth week, whelping (birthing) is inevitable.