It is easier to get two young animals to live in harmony as they will
grow up together, however with a bit of time and patience (it may take
up to 6-7 weeks) a young kitten or puppy can be introduced to an older
pet.
Your old pet should be exposed to as many new situations, visitors and
pets as possible. This will help them to adapt to any new pets in the
house.
If you are getting your new pet from a shelter then you should ask the
staff about its behaviour towards other animals; does it have a
history of aggression toward other animals?
When your new pet arrives it will be very tempting to spend a great
deal of time with it, perhaps at the expense of your old pet. You
should lavish praise and attention on your old pet to avoid any
jealousy issues, which can occur. When you are dealing with a puppy
and an adult dog, you should resist the temptation to be
overprotective of the young dog. If the adult reprimands the puppy try
not to interfere, this will upset the normal household hierarchy and
may lead the older animal to use excess force in the future....
http://groups.google.com/group/dogfoodmave
