Ultrasound is used to confirm pregnancy in both dogs and cats. Typically, you are able to see the developing fetuses in 25-28 days. Ultrasound is usually recommended between 28-30 days. At this time, you can see the baby’s heartbeats and some developing characteristics, as well as evaluate for any unforeseen problems. At this ultrasound the number of puppies can be predicted along with a due date.
Sometimes owners would like to have a more definite count. If this is desired, a flat film x-ray is recommended usually 1 week prior to due date. This allows the doctor to count the number of skeletons, but even this is still a guesstimate.