# Dog Pregnancy Ultrasound and X-Ray: When and What to Expect A dog pregnancy ultrasound is the earliest and safest way to confirm that your dog is pregnant, and it can usually be done about three weeks after breeding. X-rays come later and answer a different question, mainly how many puppies are coming. Each test has a best time window, and using them in the right order gives you the most useful information for planning the birth. This article is educational and is not a substitute for veterinary diagnosis or treatment. ## Quick Answer - Ultrasound can detect pregnancy as early as 17 to 20 days after the LH surge, which is roughly 3 weeks after breeding [1]. - Radiographs (X-rays) can confirm pregnancy from about day 43 after the LH surge, but they are most accurate for counting puppies after day 55 [1][2]. - Ultrasound is best for confirming pregnancy early, checking fetal heartbeats, and estimating due date. It is not reliable for counting puppies. - X-rays are the best method to determine litter size, which helps you and your veterinarian plan for whelping and decide whether a cesarean section may be needed [2]. - If you do not know the breeding date, your veterinarian can use fetal development and fetal dentition on X-ray to estimate how close your dog is to term [2]. ## What Is a Dog Pregnancy Ultrasound and Why Is It Done? An ultrasound uses high-frequency sound waves to create a real-time picture of your dog's uterus and its contents [3]. The veterinarian moves a small probe over your dog's belly, and the machine builds an image from the echoes that bounce back. Because the image is live, the veterinarian can watch the heart beating and see the puppies move. Ultrasound is the modality of choice for early pregnancy diagnosis in dogs [1]. It can confirm pregnancy as early as 17 to 20 days after the LH surge, which is the hormone surge that triggers ovulation [1]. If you know the breeding date, that usually works out to about three weeks later. Ultrasound can also assess fetal viability and development, show some malformations, and give an early read on fetal stress [1]. Doppler imaging can add information about blood flow when needed [1]. Ultrasound is also used throughout pregnancy to estimate gestational age, judge fetal maturity and readiness for birth, monitor high-risk pregnancies, and evaluate a dog who is having trouble delivering [4]. As ultrasound equipment has improved, veterinarians can use it for more of the reproductive evaluation than ever before [4]. One thing ultrasound does not do well is count puppies. If you are asking how many puppies an X-ray shows, that is a radiograph question, not an ultrasound question. ### What Ultrasound Can and Cannot Show Ultrasound can show: - Pregnancy itself, often before the puppies are visible on an X-ray - Heartbeats and fetal movement, which speak to viability [1] - Fetal development over time, including measurements used to estimate due date [1][4] - Signs of fetal stress in some cases [1] Ultrasound cannot reliably show: - An exact puppy count - Fetal dentition, which is a radiographic milestone near term [2] ## Dog Pregnancy X-Ray: What Radiographs Show and When A dog pregnancy X-ray, also called a radiograph, uses x-ray photons to create a two-dimensional image based on how different tissues absorb or scatter the beam [5]. Bone and mineral show up clearly, which is why fetal skeletons become visible as the puppies mineralize. Radiographs of the caudal abdomen can diagnose pregnancy from the 43rd day after the LH surge onward [1]. They also allow assessment of fetal size and litter size [1]. For counting puppies, though, the best results come after day 55, when late gestational radiography is considered the best method to determine litter size [2]. Fetal dentition becomes visible at term, and seeing teeth on the radiograph can confirm that the puppies are developed enough for an elective cesarean section when ovulation timing is not available and breeding dates are vague or spread over several days [2]. That is a useful safety net when you truly do not know when your dog was bred. ### Why Litter Size Matters for Whelping Knowing the number of puppies changes how you plan. If your dog has a large litter, your veterinarian may want to monitor labor more closely. If a small litter is expected, a prolonged labor with no puppy delivered becomes more concerning sooner. Radiographs also help assess fetal size, which matters when a puppy may be too large to pass [1]. Both ultrasound and radiography give complementary information about possible labor complications and help guide decisions about obstetric intervention and further management when a dog has dystocia, which means difficulty giving birth [1]. If you are tracking dates at home, a [dog pregnancy calculator](/knowledge/veterinary-medicine/reproduction/dog-pregnancy-calculator) can help you estimate the due date, and [dog pregnancy symptoms](/knowledge/veterinary-medicine/clinical-methods/dog-pregnancy-symptoms) can help you recognize early changes. For a broader look at how pregnancy is confirmed, see [Canine Pregnancy Diagnosis: Ultrasound and Hormonal Assays](/knowledge/veterinary-medicine/theriogenology/canine-pregnancy-diagnosis-ultrasound-hormonal-assays). ## How to Prepare for the Appointment Preparation is simple for both tests. - Feed your dog normally unless your veterinarian says otherwise. Most pregnancy imaging does not require fasting. - Bring your breeding dates, or the dates of possible breeding, if you have them. Timing drives everything. - Bring any prior records, including progesterone or LH testing results. - Keep your dog calm on the way in. Stress can affect reproductive processes, and transport stress is a known concern around whelping [6]. - Ask ahead whether the visit is for diagnosis, due date estimation, or a puppy count, so the right test is scheduled at the right time. If your dog is anxious or dislikes belly handling, tell the clinic when you book. A calm, cooperative dog makes the scan faster and clearer. ## What Happens During Ultrasound and X-Ray ### During the Ultrasound Your dog usually lies on her side or back on a padded table. The veterinarian clips or wets a small patch of fur on the belly and applies gel. The probe is moved slowly across the abdomen. The scan is painless, and most dogs tolerate it well. The image appears on a screen in real time, and the veterinarian can freeze frames or record short clips [3]. The exam often takes 10 to 20 minutes. If pregnancy is very early, the veterinarian may need to look carefully and may ask you to return in a few days if nothing is seen yet. That is normal, not a sign that something is wrong. ### During the X-Ray For radiographs, your dog is positioned on her side or back on the x-ray table. The machine produces x-rays using adjustable exposure settings, and the resulting image shows the internal structures [5]. Two views are common, one from the side and one from the belly. The whole visit is usually short. Some breeders worry about radiation and stress from X-rays in late pregnancy [6]. In human medicine, radiation thresholds and risks are well documented, but similar information is not available for dogs [6]. Talk with your veterinarian about the benefits of an accurate puppy count versus any concerns you have. In most cases, the information gained helps prevent a worse outcome during whelping. ## Recovery Timeline and Home Care Both procedures are outpatient. Your dog goes home the same day. There is no recovery period in the usual sense, but here is what to expect. | Time After Appointment | What to Expect | What You Should Do | |---|---|---| | Immediately after | Dog is alert and comfortable. Gel may remain on the belly after ultrasound. | Wipe off gel if needed. Offer water and a normal meal. | | First 24 hours | Normal behavior, appetite, and activity. | Watch for any vomiting, pain, or changes from baseline. | | Until whelping | Pregnancy continues on its normal timeline. | Follow your veterinarian's plan for nutrition, activity, and monitoring. | | Around day 55 onward | If an X-ray was done, you should have a puppy count. | Use the count to plan whelping supervision and when to call the clinic. | | At whelping | Labor begins on its own schedule. | Track time between puppies and call your veterinarian if labor stalls. | ## Possible Complications and Warning Signs Ultrasound and radiography are low-risk procedures. The main limitations are timing and image quality, not harm to your dog. Call your veterinarian if you notice any of these after an appointment: - Vomiting that does not stop - Refusing food for more than a day - Pain when you touch the belly - Vaginal discharge that is bloody, green, or foul smelling - Fever or lethargy - Any sign of labor before the expected date During pregnancy, contact the clinic if your dog stops eating, seems uncomfortable, or has any discharge. If you are unsure whether something is urgent, call. It is always acceptable to ask. ## Questions to Ask the Veterinarian - Based on my breeding dates, when is the best time for an ultrasound, and when should we do an X-ray? - Can you tell me how many puppies you see, and how confident are you in that number? - What is the estimated due date, and how was it calculated? - Does this litter size change how we should plan for whelping? - What signs of labor should make me call you right away? - Should we plan for a cesarean section, or can we wait and see how labor goes? Write the answers down. You will want them at 2 a.m. when labor starts. ## Limitations and When to Contact a Veterinarian No imaging test is perfect. Ultrasound may miss an early pregnancy, and it cannot give a reliable puppy count. Radiographs are excellent for counting after day 55, but they are less useful earlier, and positioning or a large litter can make the count harder [2][1]. Embryonic resorption, in which some conceptuses are lost early, occurs in a meaningful share of pregnancies and can change the final number of puppies [7]. In one study, at least one resorption site was visible in 48.3% of pregnancies examined by ultrasound at 21 to 30 days post-ovulation, and the embryonic resorption rate was 14.2% [7]. That means an early count, even if it were possible, would not be the final count. Contact your veterinarian the same day if your dog has vomiting, refuses food, has belly pain, or has any vaginal discharge. Go to an emergency clinic now if your dog is in active labor with strong contractions for more than 30 minutes without delivering a puppy, if she has a puppy stuck in the birth canal, if she is straining with no progress, or if she seems weak, collapsed, or in severe pain. Schedule a routine visit to plan imaging if you suspect pregnancy and have not yet confirmed it, or if you know the breeding date and want to time the ultrasound and X-ray correctly. Every dog is different, and your veterinarian needs to evaluate your individual dog to give you specific advice. ## Frequently Asked Questions ### How soon can an ultrasound detect pregnancy in a dog? Ultrasound can detect pregnancy as early as 17 to 20 days after the LH surge, which is about three weeks after breeding [1]. If your dog was bred over several days, the timing is less exact, so your veterinarian may suggest waiting a few extra days. A negative scan very early does not always mean she is not pregnant. ### Is an X-ray or ultrasound better for counting puppies? An X-ray is better for counting puppies. Late gestational radiography after day 55 is the best method to determine litter size [2]. Ultrasound is the better choice for early diagnosis and for checking fetal heartbeats and development [1][4]. Many veterinarians use both, one early and one late. ### Can an ultrasound tell me the due date? Yes, ultrasound can help estimate gestational age. Measurements of fetal and extrafetal structures allow calculation of gestational age and therefore the time of parturition [1]. Your veterinarian may combine those measurements with your breeding dates for the most accurate estimate. ### Is it safe to X-ray a pregnant dog? Diagnostic imaging is routinely used in pregnant dogs, and radiography is one of the two most common exams for pregnancy diagnosis and litter size [6]. No radiation threshold data specific to dogs is available, and some breeders have concerns about radiation and stress [6]. Discuss the risks and benefits with your veterinarian so you can make an informed choice. ### What if my dog was bred on unknown dates? Your veterinarian can still help. Fetal dentition becomes visible at term, and its appearance can confirm that the puppies are developed enough for an elective cesarean section when ovulation timing is not available and breeding dates are vague or spread over many days [2]. Ultrasound measurements can also help estimate gestational age [1]. ## Related Articles - [Canine Pregnancy Diagnosis: Ultrasound and Hormonal Assays](/knowledge/veterinary-medicine/theriogenology/canine-pregnancy-diagnosis-ultrasound-hormonal-assays) - [dog pregnancy symptoms](/knowledge/veterinary-medicine/clinical-methods/dog-pregnancy-symptoms) - [Ultrasound of the Canine and Feline Liver and Biliary System: Normal and Abnormal Findings](/knowledge/veterinary-medicine/diagnostic-imaging/ultrasound-canine-feline-liver-biliary-system-normal-abnormal-findings) - [Ultrasound of the Canine and Feline Gastrointestinal Tract: Normal and Abnormal Findings](/knowledge/veterinary-medicine/diagnostic-imaging/ultrasound-canine-feline-gastrointestinal-tract-normal-abnormal-findings) - [Dog Pregnancy & Whelping Date Calculator](/knowledge/veterinary-medicine/reproduction/dog-pregnancy-calculator) - [What Is a Vet Ultrasound? Cost and What to Expect for Your Pet](/knowledge/veterinary-medicine/online-vet-and-care-costs/vet-ultrasound-cost-expect) ## References 1. [Diagnostic Imaging during pregnancy of the dog](https://pubmed.ncbi.nlm.nih.gov/37820618/). Tierarztliche Praxis. Ausgabe K, Kleintiere/Heimtiere, 2023. 2. [Pregnancy Determination in Bitches and Queens - Management and Nutrition](https://www.merckvetmanual.com/management-and-nutrition/management-of-reproduction-dogs-and-cats/pregnancy-determination-in-bitches-and-queens). Merck Veterinary Manual. 3. [Ultrasonography in Animals - Clinical Pathology and Procedures](https://www.merckvetmanual.com/clinical-pathology-and-procedures/diagnostic-imaging/ultrasonography-in-animals). Merck Veterinary Manual. 4. [Ultrasonography for the evaluation of pregnancy in the female canine](https://pubmed.ncbi.nlm.nih.gov/37724659/). Reproduction in domestic animals = Zuchthygiene, 2023. 5. [Radiography of Animals - Clinical Pathology and Procedures](https://www.merckvetmanual.com/clinical-pathology-and-procedures/diagnostic-imaging/radiography-of-animals). Merck Veterinary Manual. 6. [Diagnostic imaging in the pregnant bitch: risks, advantages, and disadvantages](https://pubmed.ncbi.nlm.nih.gov/40538721/). Frontiers in veterinary science, 2025. 7. [Embryonic resorption rates at canine pregnancy diagnoses: A retrospective evaluation](https://pubmed.ncbi.nlm.nih.gov/37201297/). Theriogenology, 2023. ## Further Reading - [Merck Veterinary Manual: Dog Owners](https://www.merckvetmanual.com/dog-owners) - [Cornell Richard P. Riney Canine Health Center: Canine Health Information](https://www.vet.cornell.edu/departments-centers-and-institutes/riney-canine-health-center/canine-health-information) - [American Veterinary Medical Association: Pet Care](https://www.avma.org/resources-tools/pet-owners/petcare)