How long after my dog starts showing will she give birth? - Animal Hospital Of Statesville
So usually, they don't start showing until the last trimester, so that's the last two to three weeks. So if you're at that point and she's ballooning out a bit, then you should be on alert that they may be coming soon. Bring her to a vet, so we know how many to expect.
Also, at about a week before the due date, if you start taking the temperature twice a day, you can look for a drop in temperature, usually about one degree from her baseline, and it will get you around 97 or 98. It doesn't always happen. But if it does happen, usually about 24 hours later is when you'd expect her to start having the puppies.