If you do x-rays at day 58-60 of gestation to get a puppy count you can determine if the pups are very large and may be difficult to whelp naturally. Or if there is a singleton (only one pup) it can prevent hormones from kicking in and labor to start.
The other reason to x-ray head count is to know how many pups she has and better idea of when she is finished whelping. You need the spines and skulls to be calcified in order to see on x-ray so best to wait till at least day 58 of gestation.
Progersterone tesing prior to breeding to know when the dog ovulates is best so you will know exact due date of 63 days from ovulation (not from first breeding) and when to x-ray.
There are also times when the dog is in labor and something is not right and you need to head in for an emergency section.
If she is having contractions and pushing but not producing a pup for quite some time – put on a surgical glove and gently reach inside the vulva to feel a pup in the birth canal or not.
Take her out on a leash and walk her (have a towel with you to catch a pup) as this can help move things along and she can squat and deliver in the yard. Or put her in the car and drive around – I have produced pups with both methods.
If none of that works there is a chance a pup is stuck and if it is in the birth canal that means the umbilical cord has detached from the wall and the pup is not getting any oxygen. There could also be pups behind it that have detached and also in danger.
Off to the vet to be sure.
I had a situation where the dog was not contracting but trying to push – especially while out walking. Things were just not progressing. Then she produced a small amount of dark green discharge which is a concern and a sign of a pup detached and possibly suffocating. And on top of that a lot of dark blood.
Off to the vet for an emergency section. First pup was stuck and all 9 pups were in the same horn – very rare according to my vet. They have never seen that many all in one horn.
They were able to save all the pups thank God.
Its never an easy decision to know whether to rush in for a section but best to go to save the pups and the mother. Notifying your vet in advance of due date and having them on call on the phone to help you make a decision to go in to the vet or not is a good idea.
Anyone expecting a litter I wish you all the best for an uneventful whelp.