Pregnancy tests for dogs

X-rays and ultrasounds are useful tools for diagnosing pregnancy in dogs and determining how many fetuses the dog is carrying.

Ultrasound

An ultrasound can be performed from the 21st day after mating, when the fetus becomes visible in the uterus. However, at this early stage, it may still be too soon to confirm or rule out pregnancy, which is why an ultrasound is often recommended from the 28th day or later.
During the exam, the dog’s owner can usually stay nearby to comfort her. The procedure is painless and does not require sedation. The dog may lie on her back or side, and her belly is gently shaved. Then, a probe with ultrasound gel is placed on her abdomen. The examination takes around 15 to 20 minutes.
Ultrasound is not ideal for counting the number of fetuses, which is why an X-ray is often a better option for that purpose. X-rays can be performed starting from day 42 of pregnancy.

X-ray

From the 42nd day of gestation, it’s possible to confirm pregnancy via X-ray, as the fetuses' skeletons are clearly visible. X-rays are particularly useful for estimating the number of puppies. To do this, the vet typically counts the number of skulls or vertebrae seen in the image.
It can sometimes be challenging to determine the exact number of fetuses—especially if there are many—because it may be hard to distinguish them all clearly in the image.