The 63-day rule is very accurate if calculated from the moment of ovulation. However, tracking from the mating date introduces variables because sperm can survive inside the female for up to a week before fertilization occurs. Therefore, calculating from the mating date gives an accuracy window of roughly +/- 3 to 5 days.

Most veterinarians recommend scheduling an ultrasound approximately 25 to 28 days after the mating date. At this point, fetal heartbeats can be detected. For counting the actual number of puppies, an X-ray around day 45 to 50 is required, as distinct puppy skeletons are fully calcified by then.

The most reliable indicator of imminent labor is a drop in the dog’s rectal temperature. Normally sitting between 101-102°F, the temperature will suddenly drop below 99°F, signaling that labor will begin within 12 to 24 hours. Behavioral signs include heavy panting, restlessness, pacing, and extreme nesting behavior.

No, this is a common misconception. For the first four to five weeks, the embryos are tiny, and overfeeding will only cause the mother to gain excess fat, potentially complicating labor. Only after week 5 or 6 should you transition to high-calorie puppy food and gradually increase portion sizes by about 30-50%.

If your dog exceeds the 63-day mark by a couple of days, remain calm, as fertilization may have happened late. However, if she hits day 68 or 70 from the last mating date, or if she has green/black discharge without producing a puppy within a few hours, contact an emergency veterinarian immediately.