While dogs typically stay pregnant for a particular length of time, every dog is different, and the length of the pregnancy is never a scientific certainty. Your dog's pregnancy should be carefully monitored by a veterinarian as labor approaches, and if you notice any abnormalities -- including an irregularly long gestation period -- contact your vet as soon as possible.
Your dog's pregnancy may last longer than two months -- it may also be shorter. A healthy gestation period lasts between 56 and 66 days, and the average length is between 63 and 65 days. You'll know that labor is approaching when your dog becomes noticeably restless -- she may also lose interest in her food and stay in her nesting box. If your dog doesn't show these or the other signs of labor explained by your vet by day 64 or so, contact the vet's office. You may need to take her in for an appointment to make sure that there are no problems with the pregnancy.