You're counting down to that 63rd day after conception, when the average pregnant canine gives birth. Of course, pregnant dogs don't know that's the due date, so their pups might arrive a few days earlier or later. If you're not sure when the dog conceived, you must pay even closer attention to physical signs. Just be prepared in advance, with your vet's contact information handy and a whelping box waiting for mother and puppies.
One of the best ways to determine when your dog is due to deliver is by taking her temperature twice daily. Normally, a dog's temperature ranges between 101 and 102 degrees Fahrenheit. If your dog's temperature drops below 100 degrees, expect labor to commence within 24 hours. This temperature drop relates to release of prostaglandin -- hormone-like fatty acids that aid in uterine contractions -- as well as a sudden drop in progesterone, a hormone necessary to maintain pregnancy.
You've noticed that your dog's mammary glands are enlarging. One to three days before delivery, milk production usually begins. If you gently squeeze a nipple, milk comes out. This varies from dog to dog, with some mothers-to-be leaking milk a full week before having puppies.
When early labor starts, you'll notice behavioral changes in your dog. She becomes restless, frequently getting up and down. She might start pacing, panting or trembling. She doesn't want food, but make sure she has water available. While some dogs want to be alone, many start clinging to their person. Your dog will probably display nesting behavior, going back and forth to the whelping box you've prepared for her and "rearranging" the blankets and rugs inside it. This initial labor stage lasts six to 12 hours.
During the first stage of labor, your dog's cervix continues to dilate. When you see her start straining, active labor begins. Fluid draining from her vulva means her water is breaking and the first puppy is on the way. As each puppy is born, the mother should lick away the amniotic sac covering the baby's mouth. If she doesn't, you must perform that task gently so the puppy can breathe. Otherwise, don't interfere with the birth process unless there appears to be a problem. Puppies should arrive every 20 minutes to an hour, although the mother might take a rest for a couple of hours after giving birth to a few babies. If labor doesn't resume within four hours, or if your dog is in active labor for more than two hours without producing a puppy, call your vet.