This is a good explanation that I found on the internet:
Quote:
|
One interesting fact about the canine reproductive cycle is that the dog goes through roughly the same hormonal changes whether or not she is pregnant. For this reason, there is no progesterone blood or urine test to diagnose pregnancy in dogs. There is, however, a blood test that will detect relaxin, a hormone that is produced in pregnant dogs but is not found in non-pregnant dogs. This test may be performed mid gestation, which occurs at around the same time that your veterinarian can palpate the fetuses.
|