My Staffy is 3 years old and has already had one litter of pups, she is in season again and is currently on day 15, the problem i have is this, her first time around she was 13 days when she conceived, i have been trying this time since day 12, ad althouh she is standing for the stud dog he cannot penetrate her, she is still bleeding although only slightly, still quite red in colour. She doesn't look very swollen at vulva, has anyone any advice? taking her back to stud again today.

Would seem she is not ready, give them a break for 48 hours and try again, could be that it is not on this time, sometimes the bitch knows best and there is some reason she is not going to accept the dog. Did you have her general health checked before you tried to mate her?

some of our bitches dont stand properly until around day 16 - 20, one bitch we have hates to be mated and protests by growling, even when she is on the correct day and is swollen enough she has been like this every season we usually put a plastic baskwerville type muzzle on her and hold her head whilst talking to her to keep her calm this seems to do the trick. if you have someone experienced to help you supervise the stud dog you should try again in a day or twos time

Bitches can vary from season to season.  Have just had my 6 1/2 year old bitch mated.  for her first litter she stood on day 15, her 2nd day 16 and 17, this time she wasn't ready until day 19 and now at what should be day 23 is still very much in season, though going over, but I wouldn't trust her near another male for probably another four or five days.