We just brought a new 3 1/2 month old Rat Terrier home.  Our three-year-old Jack Russell Terrier is acting like she is something to be hunted.  Normally our Jack Russell is extremely sweet, but this seems like an instinctual drive to nip at her.  We put the new puppy in a crate and let the JR Terrier smell/explore, but then he bit the RT puppy on the lip.  Today is day-two and we have been holding them next to each other and letting them sniff.  I am so worried about letting the older JR Terrier free because I would never forgive my self if something happened.  If anyone has any ideas, I would really appreciate it!

Did you allow the 2 dogs to meet in a neutral place or did you bring the puppy right into the Jack's house?  It's best for 2 dogs to meet in a neutral place.

Also, are you sure the Jack is being agressive or is he simply trying to play?  No offense intended, I'm sure you know your dog, but when ratties play it often looks (and sounds) like they are being aggressive when they're just playing,,, JRT's may be the same way.....  Obviously, if he's injured the puppy then the "play" has gone too far.

It's unusal for a grown dog to injure a small puppy.  I'm sure the others will have better advice when they check in....weekends can get slow with posting on here.  Meanwhile never leave them alone unattended. JMO

Oh, and welcome!!! We want pictures of both of your babies!

Thank you so much for your replies!  To answer some of the questions:  No, unfortunately, we didn't think to introduce the dogs in a neutral place.  Yes, we have been giving our three-year-old JRT TONS of attention and praise.  Our JRT's name is Watson and we still don't have a name for the precious new addition.  We have three children -- all with different ideas. I am hoping to decide by the end of today so that she gets to know her name. Yes, I do think the JRT's intent is that of a predator, which is why I am so worried.  We have a guinnea pig and whenever the JRT sees it he goes wild (it is always protected, but sometimes when we clean the cage, the JRT can see it).   When our three-year-old JRT bit our new Rat Terrier's mouth (through the crate) it drew blood and my husband has been holding him back when his mouth curls up and he seems likely to strike.  We have been trying to expose them to each other for about 20 minutes at a time, giving plenty of praise to the older dog.  Normally our older dog is a sweetheart, so I truly hope they grow to love each other.   I'm still trying to figure out how to insert a photo, but will post one soon.

Hopefully you can view the picture now

Thank you -- I will try the training forum.  This has been very helpful!

Hope that they are getting along better now!

We are adding a RT puppy  (named her Pokey, because she looks like the Pokey puppy in the Golden Book) to our family, picking her up this week in Orlando.  It is a long drive, so we are bringing our girl Lacey and they will meet out of the house.

Lacey is very laid back when other dogs come into our house, so we are hoping that she will have an easy time with the new addition.