Introducing a new dog has completely changed my other dog? Why?

[dakota72845]

Ok heres the thing I have a chihuahua (he stays in the house full time) and a Springer Spaniel (full time outside dog) these two usually get along fine. Well today my friend gave me a male un-neutered boston terrier so I brought him home and put him in the fence with the spaniel and right away they started fighting, the spaniel attacked him, so i got on to the spaniel and tried to calm them both down, then the boston started humping on the spaniel over and over again and the spaniel would let him do it for awhile then would attack him, keep in mind both the spaniel and the chihuahua are neutered they are all males but the boston is not neutered, well eventually the spaniel was trying to kill the boston he would get him down and shake him so hard and not stop to the point the boston would look dead, and then we would have to just keep on and on til we finally would get him pulled off the boston. So after 2 hours of this I decided to call my friend and tell her Im taking him back to her house before he gets killed. Luckily he is ok and I am going to help her find him a home for him. But heres the thing after I got home I took the little chihuahua out in the fenced yard to do his business and it was like the spaniel was trying to even pick a fight with him, and he never did that before. So now I am watching him all the time to make sure he doesnt hurt the little chihuahua. will everything go back to normal after the spaniel gets calmed back down or has this fighting changed him to where all he wants to do is kill now?
I have taken the boston back to the owners, he upset my dog too much to be able to keep him.

And for the other person I did scold the boston for doing the humping, I even thumped him on the nose eveytime he did it. But if didnt help at all.

 

[Aduial]

Well that was just about the worse way to introduce dogs. You need to get help with a trainer now. Neuter that dog too.

 

[Audrey]

It sounds like your Springer Spaniel and the Boston Terrier were trying to establish a hierarchy. You should never have introduced the Boston Terrier to the Springer Spaniel on his territory. You should have introduced them on neutral ground (an area neither of the dogs have claimed). Additionally, you should have leashed both dogs and monitored them very closely ( in case you needed to break up a fight).

Regarding your Springer Spaniel snapping at your Chihuahua, it may be because you Springer Spaniel was dominated ( by the Boston Terrier) and now wants to reinforce his position (now that the Boston Terrier is gone).

Things should be back to normal soon. You should definitely educate yourself on canine behavior, hierarchy, etc.

 

[Imran Ahmed]

For some days, try to keep your spaniel away from your chihuahua or otherwise your both dogs may kill themselves each other!... Take care !....

Imran

 

[queen of answers ?]

Its always hard to psychoanalyze dogs, and why they do the things they do.
It appears your Spaniel's position of king of the backyard was challenged by a unknown outsider. Dogs take "their turf" very seriously.
You may have to get him re-acquainted with the chihuahua again
Maybe have a family night watching TV..sit on the floor holding the chihuahua, and petting the spaniel. Get that one big happy family feeling going again. He's suffered some definite trauma.

I think he'll be ok, but needs some time. Your vet can give you some anxiety pills that will help calm him down.