Dogs are pregnant for an average of 62 days, according to a scientific study that looked at 77 different breeds of dogs. The researchers determined that the exact gestation period depends upon the dog’s breed and the litter size.
It’s important to realize that pregnancy starts 62 days from the day she ovulates and that is not necessarily the day she is bred. Because semen can survive for several days inside the female reproductive tract, the length of time from breeding to birth varies from 57 to 67 days.
How to Tell She’s Pregnant
If you purposely bred your female dog, or observed an accidental mating, an ultrasound is the earliest and easiest way for your veterinarian to determine if your dog is pregnant. An ultrasound can show a pregnancy at 21 days or so, giving you the most time to prepare for the puppies.
If an ultrasound is unavailable or too expensive, at about 30 days after ovulation, your veterinarian may be able to palpate uterine enlargements that contain the fetuses. This does, however, require a slender, relaxed momma and an experienced veterinarian.
Otherwise, X-rays can be done around 45 days after ovulation, but she will be due in just a few weeks.
Note: There is a blood test your vet can run called a relaxin assay that can detect pregnancy at around 25 days, but it does not recognize whether there are viable pups or not. Also, relaxin concentrations stay high for several weeks even if the mom miscarries or fetuses die and are resorbed. Relaxin is a useful test for identifying false pregnancy, however, as the levels do not rise with false pregnancy.
Signs of Pregnancy
If your female dog mated with a male unbeknownst to you, there will likely be no outward signs of pregnancy for the first several weeks. At about five weeks, you may see outward signs, including:
- Swollen nipples
- Mammary enlargement
- Weight gain
This means, if you see these changes, and your dog was in heat five to six weeks earlier and unsupervised at any point around that time, it’s time to make a veterinary appointment to find out if you’re about to become a puppy grandparent. (Note: There is a possibility of false pregnancy, called “pseudocyesis,” in dogs where the female shows these physical changes but is not pregnant.)
