Hello.  I am so thankful for this terrific website! 

I am asking for help with a brand new 3 1/2 month old RT that I recently brought home.  Daisy is the sweetest creature and we are delighted to have her in our family!  One problem:  our three-year-old Jack Russell Terrier is instincutally trying to lunge at her.  Our JR Terrier, Watson, is a terrific family pet -- we couldn't have been happier with his personality and his demeanor.  He doesn't chew anything except his toys, he is EXCELLENT around just about everyone and is an all-around sweetheart.  Last year, however, he nipped at another dog that a friend brought over to play with.  He only nips (with seemingly bad intent) at smaller dogs, but not all of them.  He attended training classes when he was a puppy, but he rarely leaves our home, and, therefore, isn't as social as he probably could/should be.  There is always so much love for him at our house -- he gets constant attention, runs around, etc, so I have never felt guilty about not socializing him more, but now I realize this may be a real problem when introduing a new puppy.

Enter the new puppy:  Daisy is the sweetest thing we have met (since Watson!).  She is playful and loving -- even her bites are gentle and cautious.  BUT, Watson (our three-year-old JR Terrier) seems to be lunging at her with bad intent.  I don't know for sure that he would hurt her because his disposition is so scary that we haven't let them loose around eachother (it has been three days since we brought the new puppy home).  I posted several messages on another forum, and I was asked if it could be the type of behavior that is aggressive or just something that dogs will do when getting to know eachother.  I am convinced that my older dogs behavior could potentially critically injure the puppy.  I know my older dog well, and I have seen him express the same type of agressiveness around our pet guinnea pig.

Since bringing the new RT home three days ago,  we have tried to gradually introduce the two dogs to eachother.  My older JR Terrier has been so excited, he is chomping his mouth in a strange way that I have never seen before.  Sometimes he lunges toward the new puppy with his jaws exposed.   We let them spend time together sevral times a day (while holding both dogs) and tonight we sat down with the two dogs on our laps.  After about 10 minutes, our older JR was too excited to contain himself.  His jaws flaired back and, again, we were worried for the new puppy.  I know other people have told me that this can be nothing to worry about, but I am very worried that our older dog will badly injure the new puppy.

Sorry to run on and on...any help would be very much appreciated!!