Pregnancy confirmation is a veterinary question
An online calculator estimates dates; it cannot detect pregnancy. Your veterinarian may use several methods to confirm pregnancy and assess the dog, depending on her health and reproductive history.
Ultrasound
Ultrasonography is particularly useful for pregnancy confirmation and evaluating fetal viability during an appropriate mid-gestation period. Merck notes its usefulness at roughly 25–35 days of gestation. Your veterinarian must determine timing when the ovulation date is unknown.
Relaxin testing
Relaxin is a pregnancy-associated hormone. Tests can help confirm pregnancy during an appropriate window, but timing, false negatives and follow-up need veterinary interpretation. A negative early result does not necessarily settle the question.
Radiographs (X-rays)
Later in gestation, radiographs can help count fetal skeletons and plan for delivery. Ask your vet whether imaging is appropriate for your dog and when it would be useful.
Questions to ask the vet
- What gestation reference date are we using?
- What will this test tell us?
- When would a follow-up test be useful?
- Are there risks or symptoms that change the examination plan?
Source: Merck Veterinary Manual — Pregnancy Determination. Educational information, not veterinary instructions.