How strange, Murphy has what we call a hoolie moment when he's wet too!
I do really feel for you. Murphy was a horrid puppy and we thought we had something with serious behavioural problems. We tried everything, our last resort was trying Cesar Milan's methods and as others have said it only made him more excited. We were lucky that we found somebody who is fantastic who helped us with our problems. She suggested holding the scruff if the dog gets nasty, which I was surprised by, but only if the dog isn't wearing a collar etc and you need to get a slip lead on or something to control the dog. You'd only really need to do that if you had a really nasty dog so it can't bite the hand you're holding it with and with the other hand you can guide a lead over it's head. But I've never heard of the scruff being used in any other situation.
We found when Murphy had his hoolie moments it would be at a certain time of the day, first thing in the morning or at between 6.30-7.30pm, then again between 9-10pm so if she has certain times when she does it then make sure you put a lead or house line on her just before that time and when she kicks off she will be easier to control. Another thing we found was that he would usually be horrid when he was tired, in the morning he was just excited to be out of his crate, but at 6.30-7.30 I would have come home at about 5.30 and walked and played with him so in another hour he was tired. He'd get nasty and we'd put him in his crate and he'd almost drop off instantly. Then when he came out about 10mins-30mins later, depending on how long he slept he would be a different puppy. Again he'd be horrid between 9 and 10pm which is when he was tired again as that was his bedtime.
You're very lucky that you've got an sensible older dog who will sort her out. But remember he'll only do that if he gets a positive experience from it. I.e. if he snaps at her then she leaves him alone or settles down. But if he's forced to stay with her against his will he'll probably start to avoid her as much as he can and maybe even become afraid or unnecessarily aggressive with her. I wrote loads on a thread about mouthing a little lower down if you want to have a look at that too.
I really feel for you because they can be so difficult and nobody tells you how horrid they can be. Murphy was our first puppy, although we'd had dogs in the past, so it was a real shock to the system. But on the upside, despite him being the puppy from hell I can now trust him in almost any situation. He's still very excitable and still doesn't always come back at agility and he LOVES anybody else or any other dog and wants to talk to everyone. But at our training class even some of the most aggressive dogs have let him talk to them because of the way he approaches them now, he's also very sensible in that he just rolls over if anything has a grumble at him. He is a delight to have around and despite how horrible he was I wouldn't swap him for anything and hopefully you'll come through this and feel the same about yours.
