How to Confirm a Dog Is Pregnant: Ultrasound, X-Ray, and Hormone Tests
After a successful breeding, every breeder wants to know: did it take? The timing and method of confirmation matters — too early and you may get false negatives, too late and you've lost planning time.
Method 1: Relaxin Blood Test (Day 22–30)
What it is: Relaxin is a hormone produced only by the developing placenta during pregnancy. A blood test measuring relaxin is the earliest reliable blood-based pregnancy confirmation available.
When to test: Day 22–30 from ovulation (or Day 25–30 from breeding). Testing before Day 20 produces false negatives even in pregnant dams.
Accuracy: Very reliable when timed correctly. False negatives are possible if tested too early. False positives are extremely rare.
Availability: Many veterinary clinics run in-house relaxin tests. Some clinics send to reference labs.
Cost: Typically $50–$100.
Method 2: Ultrasound (Day 25–35)
What it is: Abdominal ultrasound visualizes the uterus and any developing embryos/fetuses. Fetal heartbeats are visible from approximately Day 25–28.
When to use: Day 25–35 from ovulation for the best results. Embryos are visible from Day 20–25 but too small to reliably count or evaluate.
What it tells you:
- Yes/no pregnancy confirmation (highly reliable from Day 25)
- Rough puppy count (unreliable due to positioning — always undercount)
- Fetal viability (heartbeats confirm live fetuses)
- Some information about fetal age if ovulation date is uncertain
Accuracy for puppy count: Poor. Ultrasound routinely underestimates litter size because fetuses are curved, overlapping, and hard to count individually.
Cost: $100–$250 depending on clinic and region.
Method 3: Abdominal Palpation (Day 28–35)
What it is: Manual external palpation of the abdomen by an experienced veterinarian to feel the uterine swellings (ampullae) produced by each embryo.
When: Day 28–35. Before Day 28, swellings are too small. After Day 35, swellings enlarge, merge, and become harder to count individually.
Accuracy: Highly operator-dependent. An experienced reproduction veterinarian can be quite reliable. A general practitioner may miss pregnancies or give unreliable counts.
Cost: Part of a routine examination. Low additional cost.
Limitations: Cannot confirm in obese dogs or very early pregnancies.
Method 4: X-Ray / Radiograph (Day 45–55+)
What it is: Radiograph of the abdomen to visualize fetal skeletons.
When: Fetal skeletons begin mineralizing at Day 42–45 but are most reliably visible and countable at Day 55. The most accurate puppy counting window is Day 55–62.
What it tells you:
- Accurate puppy count (most reliable method)
- General fetal size and positioning
- Whether any fetuses appear malpositioned or oversized (helpful for whelping planning)
Accuracy for puppy count: Best of all methods, particularly after Day 55. Still occasionally misses or misidentifies due to fetal positioning.
Cost: $100–$200.
Progesterone Testing as Indirect Confirmation
Progesterone does not confirm pregnancy — it remains elevated in both pregnant and non-pregnant dams during diestrus. However, if a dam was bred and progesterone remains elevated 60+ days post-ovulation, whelping is imminent. A sudden progesterone drop below 2 ng/mL indicates whelping within 24 hours.
Recommended Timeline
| Days from Ovulation | Action |
|---|---|
| 20–25 | Wait — too early for reliable confirmation |
| 22–28 | Relaxin blood test (first confirmation option) |
| 25–35 | Ultrasound (yes/no confirmation + viability) |
| 28–35 | Palpation by experienced vet |
| 55+ | X-ray for accurate puppy count |
| 61–63 | Expected whelping date |
Summary
The earliest reliable pregnancy confirmation is a relaxin blood test at Day 22–28. Ultrasound from Day 25 provides visual confirmation and fetal viability. Palpation is possible from Day 28–35 with an experienced examiner. X-ray after Day 55 gives the most accurate puppy count. Most breeders use ultrasound at Day 28–30 for initial confirmation and X-ray at Day 55+ for puppy count and whelping preparation.