Personality change post-partum

Question
We have a 4-year-old poodle who did not have an aggressive bone in her body until she had her first litter this past December. She was a gentle, attentive, loving mother while the puppies were nursing. We were very proud of the job she did with the puppies, and she was still her same sweet self. She warned the other animals in the house one time to stay away from the puppies box and they all honored that warning and kept their distance.
But since she has weaned the puppies when they were about 5 weeks old she has become very aggressive, even attacking the other dogs/cats in the house very viscously (sp?) if she feels they are infringing on her space or her attention from us. She even attacks her puppies and our Old English Sheepdog! She will also growl and snap at us if we do anything she doesn't like now. WHAT HAS HAPPENED TO HER? Have you ever heard of this abrupt personality change following the birth of a litter? And what do we do to get our previous mild-mannered poodle back?
Thank you for any info/ advise anyone can offer.
Barbara  

Answer
That is not normal.  Have you had the vet check her?  If nothing turns up, it may not be a problem anybody on the net can work you through.  You may need to work with a local professional dog trainer or behaviorist.  

At 4 years old, her personality should have stablized.  You could try obedience training her and other ways of establishing your place as top dog, see http://www.dogbreedinfo.com./topdogrules.htm