I am sure this is the best place to ask. Exactly how long is the actual gestation period of a dog from the egg being fertiliised to pups being born. I am sure I read somewhere that it was a fairly constant period. the differences in apparent gestation periods in dogs is caused by the eggs having to mature and semen being able to survive for several days. Does anyone know? thanks

I believe it's 63 days from ovulation. So if you progesterone test and know the exact day of ovulation, it should be 63 days from then.

great, thanks. I progesterone tested and Ovulation was a tuesday. Mating didn't happen until friday so due date is 63 days from Tuesday not friday?

yeswill be tues thats why when some bitches mate and have then early its because she mated after ovulation.

Most times I don't hormone test and the whelping date on the same bitch mated on the same days has varied, 2 days early to first mating, on time for second mating and on time for first mating.

Breeders that have mentored me go from the first mating as Day 1 and take 63 + or - from there as she can't be pregnant from before she was mated.

How long the eggs and sperm take to meet up varies and when the former is ripe enough and we have no way of knowing when that happened so we have to have a starting point to count from each time.

63 days +/-1 day from OVULATION, so 61 days +/- from actual fertilisation.

And don't forget that all bitches do not go 63 days.  One of my breeds almost always whelps on day 56.  It is perfectly viable.