From ovulation my girl is due her litter on 22nd July. She was mated 48 and 72 hours after ovulation so due dates from 1st and 2nd mating are 24th and 25th July.
I have been told by some breeders that a 'real' due date is 63 days from Ovulation.
Other have said that they always go from 2nd mating, however, not sure if many of these blood test.

Out of interest which would you go from?
I'm taking it from Ovulation at the moment and as she is expecting a large litter then maybe she could have them a few days earlier?

In your experience would you expect a bitch carrying a large litter to have them a little earlier and those having a small litter have them a little later or does it not make much difference?

Thanks :-)

It has been found if progesterone tested that bitches reliably whelp 63 days +/- 1 day from OVULATION.