How can you tell if your dog is pregnant?

Your dog may have a clear, mucous-like vaginal discharge from around the fourth or fifth week of gestation until the end of the pregnancy [source: Foster & Smith]. Your dog may have swelling in her abdomen around 20 to 30 days after conception. An experienced veterinarian can feel the swelling, which feels lumpy, and determine whether your dog is pregnant [source: DeLomba]. Your smaller dog's uterus can be palpated at around 25 to 28 days. If your veterinarian does this, he may be able to feel the fetuses. However, sometimes the puppies hide under the rib cage, in which case your vet might miss them. Your dog can have a blood test at around 28 to 30 days gestation. Your vet will try to determine pregnancy by checking for a hormone called relaxin. However, if your dog is pregnant with a small litter (one or two puppies), the blood test may result in a false negative [source: Foster & Smith]. Your dog can have an X-ray somewhere between day 45 and day 60. Your vet can not only confirm pregnancy with an X-ray, he can also see how many puppies to expect.