
Sometimes a week or even two weeks before there will be a change in her character - some bitches become a little more clingy to their owners or tetchy with other dogs - PMT basically ;) However not all do!
When actually beginning the season, her vulva will start to swell and she will have a bloody discharge - sometimes this can be very slight, so any sign of swelling start to check her regularly with a piece of white tissue. Any signs of pink to red and count that as day 1. Occasionally, there is no blood - that is far less common - but can happen.
Your bitches breeder should be able to let you know if her bitch line has a regular pattern - often that's the case and a breeder will be able to say "expect a season at X months" etc. which makes life a little easier - of course we're dealing with Mother Nature so have to always be prepared for the unexpected.
Regards, Teri :)