I had the same problem when introducing my 8 week Bailey, to my 9 month Libby (oldest is female, youngest is male). It took about 10 days for them to get to know each other, and especially for Libby to even "allow" Bailey to be in her "domain".

Keeping them apart for a few days is very important, but make sure they can sniff under the door. Also, after a few days, then switch places and have them smell where they have been. This worked really well for me.

You may see some "stalking", or "tackling" too, but my vet told me that as long as claws aren't involved, they are just playing and getting to know each other. And, if they do get to wild, I would take them back to their seperate rooms again (for a shorter period of time) and try it again.

Now they are the best of friends!

Hope this helps!

Michelle Poier