
If a bitch is ready, then she is,whatever day it is. I have a bitch that always has short seasons, and is frisky at day 6. She has had 2 litters, and mated on day 8. Her season always seems over by day 14. I once had a mismate, but chose not to have the injection. This particular bitch had odd seasons, and I didn't want her injected with hormones. She was young and healthy, and I decided that if she was pregnant, so be it. I had, in my mind, taken sensible precautions during her season. The mating took place on day 28! Afterwards, when discussing with my vet, he told me that he wouldn't have given the injection, thinking it unnecessary, as she wouldn't be pregnant. You guessed it - super easy whelping of 5 pups! So it's definitely true that bitches vary hugely.