I have just noticed that my staffie bitch has came into season again this is her 3rd one this year. I thought that they only have 2 a year, can anyone help me?  please

How long is it between seasons and what breed is she ?

How long after her last season? Frequent seasons, or what appear to be frequent seasons, can be a sign of Pyometra. It usually occurs about 6 weeks after a season, and the discharge will smell unpleasant.

The average bitch has seasons every 6 months. But I don't know any bitches that have read the books ;) :D - anything between 5 and 10 months can be perfectly normal for that bitch.

How old is she? How many seasons has she had before?

Less than four months between seasons is not normal (counting from the first day of one to the first day of the next).  This can be a sign they are not ovulating or in older bitches have cystic ovaries.  In German Shepherds for example four monthly seasons are quite common.  In other breeds 9 or 1 month gaps are the norm.

My own bitches have more often than not come into season at 4 to 5 months intervals at first, but settling to about 6 to 7 months between season by the time they are around two years old.

I would ask your bitches breeder at what age and what pattern her female relatives had their seasons, as this is likely to give you a good idea of the likely pattern.

In German Shepherds for example four monthly seasons are quite common.

Very true, and I'm hearing of it more and more lately Barbara.

It has obviously been common for a long time as I saw it mentioned in the tables in the book of the bitch, easily 15 years ago.

The tables are interesting giving particular traits of breeds reproduction, like difficult whelpings, prone to inertia, short/long pregnancy, weight of pups etc.  I found it fascinating to learn the weight of giant Schnauzer pups, which is small when you think hoe big they grow.