Normally you see milk production the last week or so of pregnancy. During the first and second week of pregnancy your female may experience morning sickness and possible personality changes. Not much goes on the third week of pregnancy though the embryos implant in the uterus during this time.
The fourth week, mom may have a clear discharge, and mammary glands start to swell. It may be possible to feel for puppies at this point. And during the fifth week, the swelling of her belly becomes noticeable and she will start to gain weight.
Mom continues to gain weight and her nipples darken and swell during the sixth week. The seventh week, you will see the shedding of abdomenal hair and she really starts to look pregnant.
Now at the eighth week, you can now feel the puppies moving around inside mom when she is at rest. The puppies can be born safely now. Milk may be expressed from mom's nipples. Mom will be extremely large.
And at the Ninth week, mom will start exhibiting nesting behavior, pant, and act uncomfortable. She will experience a temperature drop approximately 24 hours before labor starts. She will probably lose her appetite, as labor grows closer.
Pregnancy in dogs is difficult to determine in the early stages. Dogs have a heat cycle during which she ovulates and "ties" with a male in order to become pregnant. If you witnessed a tie, most likely she is pregnant. One sign is a vulva that does not completely shrink down--it stays soft and a bit more swollen than what is normally seen after a heat cycle. You may also begin to see a discharge that is sticky and dries quickly on the hair around the vulva. Around week four of the pregnancy you might notice a thickening and the start of weight gain and some swelling of the breasts.
Your Vet has a few different ways to determine if your dog is pregnant. They can run a blood test to confirm pregnancy based on hormonal levels. You can read about this test here:
They can also gently palpate the abdomen at about a month after breeding to feel for puppy bumps. They can perform an x-ray during the final week of pregnancy (8th week) and look for puppy skeletons. This method can give you a good idea of how many puppies your dog may have. Ultrasound may also be available at your vet and can help determine pregnancy in a dog. Once a dog reaches the 8th week of pregnancy, you can frequently feel the puppies moving around inside of mom. I find it best to have the dog on their side and feel between the rib cage and hindquarters above the breast area.
Puppies are born approximately 57 to 64 days after breeding with the average being 63 days depending on when ovulation occurred.
False pregnancy does occur in dogs and the symptoms are the same as if they were indeed pregnant. If in the fifth week following mating your dog is experiencing these symptoms, she may be pregnant and should be fed a high quality puppy food. I feed any female that has mated a high quality puppy food until it is determined they did not conceive.
I know you were looking for a sure-fire answer but it really is difficult.
One way of knowing when your dog with have her puppies is to take her temperature twice daily at the same time each day as her due date gets close. Keep a record of this.
A dog’s normal temperature is between 101-102.5F degrees. Her temperature may rise and fall during this time, but once her temperature falls below 99 degrees, she should go into labor in the next 24 hours. The temperature drop is due to a reduction in serum progesterone levels and signals that the dog will start labor within 24 hours.
You can read about this at:
You may also notice her breasts swelling during this last week of pregnancy and some milk leakage. Dogs will usually become restless and increase their digging and nesting behavior during the last week. You will notice an increase in her panting as well as a mucous discharge. You may also notice some abdominal contractions or rippling as her time grows closer. Do not be surprised if your dog is very restless and vomits as few times during this last week.
Once your dog's temperature has dropped, please do not leave her alone in case of complications. As she enters actual labor you should be able to see her contractions and most dogs will begin looking at their hindquarters. An increase of licking of the genitals is normal before and during labor. Be sure and have an emergency Vet’s phone number readily available just in case of an emergency during the birthing of the puppies.
Here is an excellent site about whelping.
Some other signs that my dogs always seem to exhibit are lack of appetite, frequent urination and frequent small, runny bowel movements in the day before labor starts. Frequently my dogs will start looking at their rears when the first real contractions start.
I hope you find this information helpful.