The most common misconception amongst breeders looking to get their bitch scanned is that the ultrasound machine is going to be able to provide a puppy count. Indeed, this idea is perpetuated by many ultrasound operators themselves, who have almost assumed the status of canine fortune teller in their local area, with a ten year old mechanical ultrasound machine (usually doubling as a sheep scanner) in place of a crystal ball.
While many people will swear by the puppy counts given by such individuals, their results are far more likely to be an educated guess put together from information gained through observing and palpating combined with their own knowledge of the breed, and much less to do with what they are actually seeing on their rather outdated monitors.
This is not to discredit these individuals in any way – if they are guessing correctly and people are happy with their service, good luck to them – but simply to point out that “puppy counting” is a risky sport, and not something that can be confirmed by an ultrasound machine.
Why can’t ultrasound count puppies?
The easiest time to count numbers is during early pregnancy (before 30 days) when the sacs are small and do not obstruct each other; however, not all of these will be viable foetuses and continue to develop, so relying on early sac counts can be misleading.
Thus, scanning later in the pregnancy beyond the date of normal foetal resorption would give a better indication of numbers, were it not for the fact that the puppies nearest to the probe head are likely to obscure those behind. As the foetuses grow and are no longer so clearly contained within their sacs, distinguishing one puppy from another can be extremely difficult, particularly when you consider that puppies are always moving around inside their mothers!
What to expect
A skilled ultrasound technician can certainly count heartbeats and give ballpark figures, saying for example, “I can see at least three separate heartbeats.” This is useful in confirming that a bitch is carrying more than one pup and thus putting the owner’s mind at ease regarding the elevated risk of pregnancy complications. This is not to say, however, that behind those three heartbeats are not another three, and this is where the problem of puppy counting lies.
Of course, somebody with many years’ experience with the breed, who knows how many the bitch is likely to have and perhaps knows the usual carrying positions of them, can put this information together with what they know and provide you an educated guess – which almost brings us back to the method used by our friendly local canine soothsayer.
In summary, it is important to attend a pregnancy scan with your dog knowing that puppy counting is not scientifically possible at the present time using ultrasound technology. It does not represent a failure on the part of the operator, but a limitation to our technology. The only way that puppy counts can be 100% accurate is through x-ray, which is of course far more stressful for the bitch, costly for the owner, and potentially harmful for the unborn puppies.