How Badly Do We Need to Know? Part 3

by | Dog Breeding, Dog Health

Despite the lack of safety evidence, many dog breeders use routine prenatal x-rays to get a count of how many puppies to expect. However, there are safer alternatives for counting puppies.

If you have been following this blog series, you know that in my first blog on this topic I questioned the safety of x-raying pregnant dogs. I wondered if this common practice might be contributing to the increasing rates of cancers in our dogs. I asked for research to support the claim that modern x-rays are safe for puppies since early research indicated that irradiating late-term puppies increases early and life-time cancer rates.

Breeders use x-rays to find out how many puppies to expect, one or many.

In the second blog, I presented our case study. After stopping prenatal x-rays, our early cancer rate dropped by half and the cancers that did show up in our dogs, did so 2 years later. In today’s blog, I’ll discuss alternatives to puppy-count x-rays and when prenatal x-rays are warranted.

Why do breeders do routine prenatal x-rays in dogs?

Most do so to get an idea of how many puppies to expect. If accurate, this information enables breeders to go into a whelping with more confidence, to know when their bitches have whelped the last puppy, and to know when a pup might be stuck. These are all good things that reduce breeder worry. No one does x-rays with intent to harm puppies but there are safer alternatives. So how else can we determine the number of pups to expect until science has assured us of the safety of routine, prenatal x-rays in dogs.

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How to More Safely Count Puppies

Ultrasounds can be nearly 100% accurate for pregnancy diagnosis and 90% accurate for puppy counts.

Since stopping routine prenatal x-rays, we use two primary means of verifying litter size prior to whelping. The first is a good ultrasound around 28 days post-ovulation. Ultrasound is an excellent tool for confirming pregnancy though not quite as good at giving us puppy counts.

However, skilled ultrasonographers are 90% accurate in counting puppies early in pregnancy, usually coming within one puppy of the correct count. That compares to the 95% accuracy x-rays provide. Our ultrasound experience has actually resulted in 100% accuracy on puppy counts for a dozen litters when we use repro vets with excellent ultrasound skills who are willing to take the time to count puppies. Later in pregnancy, ultrasound can give accurate puppy counts as well as provide important information regarding fetal viability and gestational age. Some ultrasonographers are even trying to determine the sex of puppies, though I’m not so sure this is worth the effort..

You may have to go looking for a skilled ultrasonographer but you can also speak to your regular repro vet to ask for a count, in addition to a pregnancy check. See if he or she will take the time to methodically work through each uterine horn to try to get a count. Be willing to pay more for the time this will take and don’t hold your vet accountable if they are off in their numbers. It will be a learning experience all around.

Fetal Dopplers are simple, safe tools to count pups and evaluate viability prior to and during birth.

The second method we use is a handheld Doppler. These simple appliances use sound waves to identify and measure heartbeats. It takes a bit of practice to learn to use them well so it might be several litters before you really get good at it but the Doppler will also give you a tool to check how well your pups are doing during whelping and to confirm there are no more pups when your bitch is done. Fetal Dopplers can be rented or purchased, depending upon your needs. Some local clubs are pooling their resources to purchase a Doppler for use by their breeders.

So Doppler and ultrasound in combination can give you confirmation of pregnancy and a reasonable idea of how many puppies to expect. And they will do so without risking the long-term health of your unborn puppies. Both ultrasound and Doppler are very safe when used a few times during pregnancy. That means once or twice each–not every week, certainly not every day!! Decades of safety studies in humans have found no detrimental effects, short- or long-term, when these technologies are used appropriately.

Bayou Boston’s video of a prenatal Doppler


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When Are Prenatal X-rays Appropriate?

Despite all of this discussion, I firmly believe there is a time and place for prenatal x-rays! They are best reserved for diagnosing potential whelping problems. If your 30-day ultrasound showed that you are expecting a very small litter of one or two puppies, x-rays can help determine if the bitch can whelp them naturally or if a Caesarean section will be likely. If your bitch has an unusual vaginal discharge or is presenting with an illness, such a maternal hydrops, an x-ray can help your vet determine what is happening within the uterus and to the pups. Or if your bitch has consistently had whelping problems in the past, you may want to use an x-ray to evaluate the likelihood of those challenges again. In these situations, an x-ray is a diagnostic tool not a routine reassurance.

If you are doing an x-ray because you are nervous about your upcoming whelping, that x-ray is routine not diagnostic. It is simply a way to calm yourself rather than provide information that will change your bitch’s treatment. I promise, you will know soon enough how many puppies you have, with or without an x-ray.

We Should Expect More

Most breeders spend a lot of time and money assuring the safety and healthy development of our dog moms and puppies. We feed the best food we can afford, provide excellent vet care, investigate flea and tick treatments, toys, treats and more. We put hours and hours into developing our puppies safely. We demand pharmaceutical, dog food, treat and toy manufacturers prove their products safe.

Yet many do not question the safety of ROUTINE fetal x-rays for pregnant bitches, despite research indicating they may increase the very cancers that are striking many of our dogs and continued caution against fetal irradiation in humans. Asking for supporting research before we allow this procedure to be done on our puppies is not a radical idea! The track record for many standard yet untested veterinary procedures is not always good. For example, 30 years of spaying and neutering nearly every young American dog is now being shown to have had detrimental effects on many of them.

If you breed or are buying a breed with a higher than normal cancer rate, perhaps it’s time to consider alternatives to prenatal x-rays until results of research is in showing them to be safe for our puppies and the dogs they will become.

References and Resources

Baby Beat.  American sources for fetal dopplers.  Be sure to get one with a digital display so you can check your puppies’ heart rates.

Gil, EMU, DAA Garcia et al. 2015.  Use of B-mode Ultrasonography for Fetal Sex Determination in Dogs.  Theriogenology, available online 1 Jun 2015.

Healthy Whelp.  Canadian source for fetal dopplers. Be sure to get one with a digital display so you can check your puppies’ heart rates.

Lenard, ZM and BJ Hopper.  2007. Accuracy of prediction of canine litter size and gestational age with ultrasound. Australian Veterinary Journal, vol 85, iss 6, p222–225.

Sirsat, PR, Raghuwanshi, DS, et al. 2008. Comparative pregnancy diagnosis and litter size estimation in bitchesJournal of Bombay Veterinary College, vol 16, iss 1, pp. 8-11S.

Torres de la Riva G, Hart BL et al. 2013. Neutering Dogs: Effects on Joint Disorders and Cancers in Golden Retrievers. PLoS ONE, vol 8, iss 2.

Wolferd, Barbara.  2014. Anecdotal Information on Canine Maternal Hydrops in the Golden Retriever. Accessed on 6/22/15 at  Cited with permission.


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  1. Hope Meaker

    I stopped using prenatal x-rays a number of years ago, but I did have an x-ray which clearly showed 6 puppies and the bitch had 12 pbabies 3 days later. We have never been able to find the other 6 babies on the x-ray, so……………

    • Gayle Watkins

      Wow, that’s probably the biggest difference between a correctly timed prenatal x-ray and actual puppy count. I’ll bet you were shocked! I would have been. Are you sure they x-rayed the right dog? 🙂

  2. Debbie

    Can you share the basics we need to be aware of when purchasing a Fetal Doppler (ie: MHz of the probe, other features at a minimum)?

    • Gayle Watkins

      Debbie, I’m sorry that we weren’t notified of your comment. In buying Dopplers, either 2 or 3 mHz will do. Most important is that there is a digital readout for heartrates. It’s also helpful to be able to plug in a headset since some bitches are bothered by the noise coming from the Doppler.

  3. Diane

    I’m wondering about reproduction issues as a result of prenatal x-rays. We have been seeing bitches not being able to conceive and males having sperm count or sperm quality problems as well.

    • Gayle Watkins

      Diane, I don’t know of any links between repro issues and prenatal x-rays but would be interested in any specifics you can share.

  4. D moore

    How often is it safe to check puppy heartrates with a hand held doppler? Can daily use cause placental problems? Or otherwise harm puppies in utero? In order to really get skilled at this and to find and follow heart rates it seems at least once a day in the last week would be necessary?

    • Marcy Burke

      Fetal dopplers are safe when used according to professional guidelines; they should NOT be used daily. Dopplers work by sending high frequency sound waves into the dam, which bounce off the puppy. The Doppler picks up the the reflected sound waves and using the Doppler Effect equation, calculates and simulates the puppy’s heartbeat. During this process, the Doppler increases the temperature of the fetus. With normal, infrequent use at the right time, that increase has no effect on the puppy but if overused or used during the first trimester, it can cause problems with placental and fetal development.

      What we do with our own dogs is count each pup’s heartbeat once or twice in the two weeks prior to whelping so we know how many pups to expect. We might break that up into multiple sessions if our bitch gets antsy and we have a large litter but we try not to listen to any one pup more than twice. Then we use the Doppler again just prior to and during whelping to monitor the pups’ heart rates to ensure all are normal.

      As far as technique, yes, it does take experience, but we do not advise trying to gain that experience by using the Doppler repeatedly on the same litter. Instead, take your time while using the Doppler, taking care not to hover too long over one area. Mark the areas you do find so you can find them more quickly should you need to down the road. If there are one or more areas you have a question about instead of keeping the probe in the area for an extended period of time, go back and check it before you finish. Since you won’t know truly know how well you did until the whelping is over, subjecting them to any possible risk from over exposure is not a risk we are comfortable with. But knowing the standard of care in human medicine is to use a doppler, we do the same with our dogs.

      There are no veterinary guidelines regarding home Dopplers at the moment but here are some human sites that might be helpful to you:

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