Aggressive behavior in 3yr old lab toward new puppy

Question
We have a 3 yr old lab who has been the perfect family dog until we brought home an 8 week old Beagle puppy 4 days ago.  Our lab growls and has bit the puppy (not drawing blood)but frightening the little one.  We have never seen this aggression towards other dogs and I am afraid he will hurt the puppy.  We are giving "Buddy" the lab lots of attention, but he still tries to hurt "Rusty" the beagle.  Any help will be great.  Thanks

Answer
The mistake you may have made was introducing them in the house.  This should have been done on neutral territory.  Imagine how you would feel if you were married for three years, and suddenly, your husband brought home a new wife!  That's how Buddy feels.  And, if he was not very well socialized to other dogs when he was young, that may add to the difficulty.  I would suggest that you not chastise Buddy, rather that you set them up to like one another.  It takes some coordination, but if you feed Buddy some treats at the very same time you feed the puppy some, they will both learn that the presence of the other dog predicts treats!!!  Conversely, you should stop feeding any treats when the other dog isn't there.  This is nothing more than classical conditioning.  However, do not try to iron out their differences for them.  You may prolong the fighting.  Most adult dogs are only telling the pup off, but don't really hurt them, and it looks rougher than it is.  Have a trainer or behaviorist observe to tell you if there is reason for concern.  Also, get the pup right in to puppy kindergarten so that he will have lots of positive experiences with OTHER dogs.