new puppy and four year old cairn terrier

Question
We have a four year old female cairn terrier and recently got a male half shih tzu half poodle puppy.  We have had the puppy for approximately six weeks and now our cairn is becoming increasingly hostile towards him.  He is significantly smaller than she is.  They often rough house and tonight she really hurt him.  She also needs to take everything away from him, any kind of toy or chew stick even when she is also given the same thing.  I am afraid she may really hurt him.  How can I be sure that she will not?

Answer
Other dogs frequently resent bringing in a new puppy.  I don't know if any of the meet on neutral ground and all that do much good.  The strange thing is, they seem to be able to tell the difference between a visit and moving in for good.  At 4 years old, the terrier may be past enjoying puppy biting games.  Part of the hostility could be just ''Keep those sharp little teeth out of my skin''.

In addition to correcting the puppy when it give unwanted attention to the terrier, also correct it when it goes beyond warning the puppy off.  Also correct it when it takes the puppy's toys.  I hope at least the puppy is in a crate when you aren't around for its protection.  

The corrections will be much more effective if you are top dog.  The key to most behavior problems is approaching things using the dog's natural instincts.  Dogs see all the people and dogs in the household as a pack with each having their own rank in the pack and a top dog.  Life is much easier if the 2 legged pack members outrank the 4 legged ones.  You can learn to play the role of top dog by reading some books or going to a good obedience class. A good obedience class or book is about you being top dog, not about rewarding standard commands with a treat. Start at http://www.dogsbestfriend.com/

Chew sticks, rawhide?  There are many toys unsafe for larger dogs that are OK for smaller ones.  Rawhide is not one of them.  Even a small dog can tear off a piece and choke on it or have an intestinal blockage.  The worst thing about rawhide is that it swells once ingested.  Discard any toy that is coming apart in pieces.