fighting labs

Question
I've had a 1.5 yr old female black lab who is spayed for about 6 months now. She has a little bit of a timid personality, but is very playful and sweet.  I just got an 8 yr old female who is not spayed.  She's very loving and sweet, but much more sedate than the younger one.  Every time my young lab gets near the older one, the elder growls and snaps at her and sends her running for her crate. They have split the house in two.  How do I teach the elder that this is not acceptable behavior, and will spaying her help the situation? I don't want my young lab to be any more timid; its taken quite a bit of work to bring her out of her shell.

Answer
The older dog is passing on a message, "Don't bug me".  Spaying might help as she won't have the flucuating hormones; however, we have a nearly 7 y/o girl who is spayed who acts the same way with our younger boys.  However, they don't care that she growls and snaps, so we usually have to tell them NO in a loud voice.  

I might work on trying to teach the younger one not to mess with the older one by having her COME when she gets close to the older one and saying Leave It if it looks like she is going to bug her.  You can use treats or a favorite toy to get her to come to you quickly when you are trying to avoid the altercation.