I have 2 dogs(dog 10mths, bitch  7mths just). The dog is normally very placid with her, even though she gives him hell when they play-fight. However, over the last couple of days he has been noticably more aggressive with her, and seems to be smelling her back end a lot more. I cant see any signs of her coming into season eg swollen vulva etc, but wonder if the change of his behaviour means one is imminent(we were anticipating one around 8-9 mths). Also when she does come into season, should we seperate both dogs for the duration, or just for a certain period of time when she is most fertile. The various books we have dont seem to be very consistent with each other, and i cant see a vet till monday to make sure.
Thank you.

It certainly sounds as though her season is on its way. When she does have her season, you would be sensible to separate them for her entire season, because bitches vary tremendously as to when they are fertile. There have been successful matings, resulting in puppies, from as early as Day 2 and as late as Day 22.

Thanks ever so much for your reply. We have managed to see a vet, and you were right, its not here yet but on its way it seems. Now the problem of keeping them apart, i will take your advice and seperate them completely just to be safe.