How can I tell if my dog is about to go into labor?

Number one, pregnancy duration is 63 days, give or take. It's a huge help if you know when your dog was bred, and so that whelping date can be established that way. So that's number one. Number two, on the assumption that you've done some of the other preliminary testing (you've had x-rays and a pregnancy test and all these other things to confirm pregnancy done), the best way to know when they're going into labor is to regularly check their body temperature.

For about a week to five days before the expected due date, start taking their temperature at least once daily, and you would typically see a temperature drop to anywhere between 97 to 99 degrees. And that typically happens roughly 24 hours before they go into labor. If their temperature is low, retake it in a couple of hours. If you get to back-to-back low temperatures in that range I just mentioned, there's an excellent chance that you're going to have puppies in the next 24 hours. So that's probably the most accurate indicator that I can think of as to when your dog's going to go into labor.

So things you would look out for would be nesting behavior—the mama dog trying to find a quiet corner and make an area for her to have puppies. You'll also start to know you're toward the end when she balloons out and the puppies are taking up space in her abdomen. And then another way to check is to have a thermometer and check her temperature twice a day, starting about a week before you expect her to be due. It's not foolproof, but if there's a drop in temperature, usually about one degree, it'll go to 97 or 98, then 24 hours after that is about when you would expect her to start whelping.