i am hoping someone can help me get to grips with the cycle that a bitch goes throuhg when in season.  my staffordshirebull terrier came into season on boxing day and thus is on day 16 (it may be day 18 as spots of blood were spotted on xmas eve) i am worried that she is still producing blood, even though it isnt that much and is knid of brown rather than red, is she past the stage where she will stand for a dog?  im just extremely confused and despite looking throughout the internet cannot find any information on the female dogs reproductive cycle

Your bitch can still stand for a dog and get pregnant.I would advise you keep her away from males for a total of 4 weeks.
Archer

As Archer says, it's still perfectly possible for your bitch to get pregnant, so keep her away from all dogs for 28 days to be on the safe side.

You'd find a copy of 'The Book of the Bitch' by Evans and White invaluable for information.
:)