A dog's gestation period is on average 63 days, according to WebMD. A dog may be in labor anywhere from 6 to 18 hours before birthing pups.
Gestation is the term used to describe the time from ovulation to birth. It is important for breeders and dog owners interested in having puppies to note that ovulation period may not be the same as the breeding period. For a normal dog, the period of gestation is between 56 to 66 days with the average falling at 63 days. The veterinarian can confirm pregnancy by ultrasound as early as the 18th day after ovulation.
The initial stages of dog pregnancy are marked by few changes. The dog will eventually display a larger stomach area, and by the fourth week of pregnancy, she may experience a few days of morning sickness.
When the dog is close to giving birth, her rectal temperature, which should normally be between 101 and 102 degrees Fahrenheit, will drop to below 100 degrees. When her temperature drops, she will most likely begin delivery within 24 hours. Signs of labor include restless behavior, shakiness and a desire to stay close to an owner. Some dogs will also vomit during labor to not have a full stomach at delivery. Labor may last anywhere from 6 to 18 hours, and the dog may begin to squat and push when the first pup is about to be born. She may do so for a half-hour before each pup comes.