
Hi,
You shouldnt have a problem if you are careful. I have just introduced a pup into a household with two existing adult dogs, Rocky, who is not teh best with other dogs, and Saffi who can be bad with other bitches.
at first, rocky wasnt too chuffed, but he took around a week to calm down, adn realise that the pup was staying. saffi thought the puppy was her personal plaything!
now they all get along fine, though i wouldnt be suprised if i have problems when Dill gets older, between him and teh other boy!
If i where you, id get a bitch.
I would make sure i had a crate for each dog, or just one if you can manage.
lastly, but i think most importantly, if your current dog has any behaviour problems that you dont want the new dog to pick up on, sort them out first! so if your dog likes to pull on teh lead, or bark etc etc, be warned, soon your new pup will do that too.
On the other hand if your current dog is an angel, then hopefully the pup will pick up on that too.
Oh, and to make it more complicated, your current dog could well go backwards, and pick up bad habits from the puppy!!!!!!!
But, its lots of fun with two, and even more with three! have fun, enjoy your dogs.
Em