Dogs attacking puppy

Question
We recently got a new puppy, she is a dobe and we have had her for over a week now.  She is about 9 weeks old.  We have two other dogs one is 5 years and the other is 2years old they were fine with the puppy when we brang her home and introduced them to her and have been good with her up until a couple of days ago I heard the older of the two dogs continously barking so I looked out the back window and the puppy was laying on her back and the other dogs were barking and nipping at her.  I know when the dogs are playing and they were not playing.  It has happened a couple of more times since.  Why would my other dogs be acting like this now when in the begging they were fine with her and we have never had any problems before.  Is there something I can do to preven this behavior, I don't want to keep seperating them because I think that will only make it worse, but I don't want anything bad to happen to the puppy.  Any suggestions would be greatly appreciated.  Thank You.

Answer
Erika, I cannot say what is causing your dogs to behave this way, or what is going on without actually seeing it in person. Older dogs WILL correct puppies when the puppies are doing something they shouldn't be doing, but it sounds to me like your other dogs do not really respect the pecking order, and when one of them goes to correct the puppy, the other one feels like it's their job to jump in too, which triggers attack mode in both of them. I would not leave the dogs alone with the puppy right now, and I would strongly urge you to consult with a professional trainer. As I said, without seeing exactly what is happening, I cannot give accurate advice here.