Dogs that are in heat can get pregnant. The gestation for dogs is around 9 weeks or 63 days on average.
Weeks 1 to 5
Up till the fifth week of pregnancy, a dog will not suffer from physical changes. There will only be a few symptoms such as morning sickness or behavioral changes. A pregnant dog will become more affectionate. Only a vet can determine a pregnancy in its early stage. Around 3 weeks after the conception, a vet can tell you if your dog is pregnant by palpating the abdomen.
After the Fifth Week
After the fifth week of pregnancy you will notice nipple swelling and a change in their color. The nipples will become more intense in color.
Week 6 and 7
After 6 to 7 weeks, your dog will look pregnant-her abdomen will be visibly larger. If you want to know how many puppies she will have, you can ask for x-rays.
Last Stage: Week 8 and 9
During the eight week of pregnancy, your dog's breasts will become larger. Towards the end of 8 weeks, you will notice that there is a white secretion coming from the nipples. This is normal, as the dog is getting ready to lactate. Your dog will be less active and will look for a quiet place to give birth.
A normal pregnancy in dogs lasts 61 to 67 days.