My oldest Boston is attacking her two year old off-spring on behalf of another Boston.

Question
I have a four-year-old female, her two, two-year-old daughters, and a one and a half year old female, who is not related and also just had some puppies.

Everyone has always gotten along wonderfully. About three weeks ago, the pregnant female suddenly growled and raised the hair on her back at one of the two-year-olds. I was there when all this played out and the two-year-old had done nothing.

As soon as the pregnant female growled and raised her hair, the four-year-old came from out of no where and jumped on the innocent two-year-old. I have no doubt she would have killed her. (This of course caused an all out attack on the innocent party by the rest of the pack)(Thank God for dog harnesses)

The strange thing is, the two-year-old can be alone with either the four-year-old or the pregnant female and there isn't a problem. As soon as the third party shows up, a free for all breaks out.

I can understand the pregnant female getting touchy and horrible to live with, I have been pregnant myself a few times and it does awful things to the hormones.

What I don't understand it the oldest dogs behavior. Why would she want to attack this two-year-old so aggressively?

Also, when the new pups are older or gone, will things go back to normal? I hate keeping my dogs separated from the family. Right now the innocent two-year-old is out in the kennel for her own protection..

Answer
Oh Susan: This is sad but very common -
Pack Order can change -

I have a friend that wrote a book called "The Human Pack" - she explains some common problems on behaviors and pack attitude.

Here are a few links to help you - I don't know if the pregnant mom has territorial aggression related to her pregnancy.
You could also take this question over to our Dog Behavior experts...
I have listed some below:
Good luck!


The Human Pack
http://www.publishersnewswire.com/booknews/2008-01-0109-PNW001.shtml

Good Article:
http://www.eioba.com/a28602/how_to_recognize_respond_to_dog_aggression

Dog Trainer at our site : All Experts
http://www.allexperts.com/ep/3333-100217/Dog-Training/Anne-Springer-BSc.htm