My goldendoodle attacked my other dog. Help

[Moe]

I have a 4 year old, 40b, female goldendoodle named Charlie. I've had her since she was 8 weeks old. She is very well trained. She passed the AKC good citizen test and we've never had a problem with aggression toward other dogs. In October we got a new puppy, her name is Lola and she is a small mix breed dog weighing 14 lbs she is 10 mo old. The dogs got along great from the beginning. No aggression, not problems around food or toys. They play wrestle all the time without incident. They don't snuggle up on the couch but they seem to get along great. 

Sunday Charlie attacked Lola when they were outside. She bit her face and left a tiny puncture on her chin and her eye was bloodshot. I was not there. My son was out in the back yard with them and he said he didn't see problems or tension between them. I kind of figured that maybe he missed something and this was a fluke. 

Yesterday I was bringing the dogs out to the back yard. Lola went out first, she was half way across the patio when Charlie just attacked her. I was walking out behind Charlie. Lola was walking in front so she was not ever looking or paying attention to Charlie. It all happened so fast but i think Charlie bit her back and rear leg. She was snarling and growling and Lola was crying. I grabbed Charlie and she released Lola. Then I held Charlie down on her side until she calmed down. The I put her in a bathroom ( I don't have a crate) for 5 minutes. I've never done this before. Normally she would freak out if you put her in a room alone but she stayed in there quietly. 

Lola couldn't walk after the attack. Her back legs were just dragging. I brought her to the vet. By the time I got there she seemed a bit better but she threw up twice and lost control of her bowels. The vet said there were no broken bones or puncture marks and she'd be fine in a few days. This morning she really seems fine. She's not even limping. She and Charlie are wandering around the house like nothing ever happened. I'm watching them closely and keeping Lola in her crate when I can't supervise them. 

My question is what do I do now?  I think it would be easier if there were a clear reason like food or toys. From what I can see they get along great. These two attacks were both vicious and seemingly unprovoked. The vet said this could be the beginning of them not getting along and that I'd have to give one of them up. I can't even think about that. Help. 

[Karen, Jasper and Jackdoodle]

How old is Lola, and are both dogs spayed? 

[Jane, Guinness and Murphy]

They got Lola as a puppy in October....good question about the spay. 

[Moe]

Lola will be a year at the end of May. I got her from a rescue in October. Both dogs are spayed. 

[Jane, Guinness and Murphy]

Do you have a Specialty Vet Hospital in your area that has Vet Behaviorists?  If so, my recommendation would be to schedule a consultation.  Often then are able to provide valuable insights that you don't get from a normal vet or even a good trainer.  I think keeping them separated when you can't monitor them is a good idea.  Often times dogs are fine with puppies but as the dog gets older they become a threat....even though there's no overt threatening behavior.  You are going to have to claim Lola IMO....Charlie is going to have to see that she belongs to you.  There's a whole process that goes with this.  I actually had to do it with my son when my Murphy decided that he didn't want him near me.  It took a little time, but it definitely worked.

[Moe]

Do you have a link to how to claim a dog? I tried googling it but got results about adopting stray dogs. 

[Jane, Guinness and Murphy]

I was taught this process by my trainer when Murphy kept trying to "guard" me by keeping my son away from me.  If my son came near me Murph would try to get in between us.  Also if he saw that my son was walking toward me in the house he would literally back him up....that scared my son and me too.  So throughout the day I would walk to my son and touch or hug him....the minute Murph would start to move toward me I would very calmly but authoritatively walk right at him backing him up and then put him in a down/stay while I went back to my son.  Would correct him every time he moved until I released him.  We did it several times a day, and it totally worked.  All this time I was also showing Murphy that I was the "leader" in the house and everything (including my son) belonged to me....nothing belonged to him.   So I claimed his toys....actually took them away from him while he was playing.  I would take a ball that he was playing with and throw it to my son to show him that it wasn't his...it was mine...and I would decide who played with it.  I think you could use a very similar strategy with Lola.  Also I would get really strict now about the rules.  Having them on the couch at your invitation should be fine, but when they're actually on your lap that sends a different message to dogs IMO.  I wouldn't do it while there are problems between the two of them, and I would not invite Charlie up unless Lola was also there with you.  For now I wouldn't let them out in the yard unless you're there.  Also I think you need to put them in a sit at the door, go out first and then invite them.  The fact that Lola went out first may have been an issue.  When I mentioned that Charlie may be starting to perceive her as a threat I didn't mean in a physical way....but in terms of where she stands in the family.  Her sitting on your lap and going out the door first may have just triggered this response....watch for other signs that could be triggers.  I'm so sorry that you had to experience this....it must have been so disturbing.  I really think that it will just take some tough consistent "rules" and you continuing to take charge.  Hope this helps.

[Jane, Guinness and Murphy]

I just remembered my trainer telling me that when dogs were having problems getting along he often recommended walking them together.  The thing is it would have to be a controlled walk where they were both at your side on a loose lead.  He said that from his experience the walk helped create a bond between the dogs and on a walk they are both clearly seeing you in the lead.  Just a thought.

[Karen, Jasper and Jackdoodle]

This has definitely worked for me and my neighbor. One of her dogs hated Jack and after we started walking together as a pack, they all became great friends. In the very beginning, we actually had to walk on opposite sides of the street! 

[Moe]

I've been waffling about how to treat the dogs because I never wanted Charlie to get jealous of the new dog. So I did the opposite of claiming her. I guess that was a mistake. 

lol I think a pack walk is a great idea. Unfortunately I have not mastered the two dogs loose leash thing yet. I have not been walking them as often as I used to because of all the snow and cold weather in the Northeast. I think this could be part of the problem. Lola is on restricted exercise for the next three weeks. When the vet turned her back paws over she did not right them on her own. I'm heading out w Charlie for a long hike right now. Hopefully it will burn off some steam. 

[Jane, Guinness and Murphy]

You can start working with the two of them together right in your own yard at first.  It took me months of working with them individually on "walk manners" and then together.  I'd just walk around the yard...stop, start, change direction.  Use lots of praise (and occasional treats) when they're by your side so they think of this time as a good thing.  Also, I know there are positive only trainers out there who will disagree, but I do think it's important to at least verbally correct when either of them starts to misbehave.....they need to know that you're the one setting the rules and you're going to see that they follow them.

[Moe]

The only other thing I can think to add is that I feed them at the same time. I alternate who's food I put down first. Lola sleeps in a crate. Charlie on the floor in the same room. (My boys room). Charlie sits on the couch next to me if I am home. Lola sometimes will sit on my lap but usually she is busy with toys on the floor. I don't have an order to who goes out the door first.

[Lucy & AnnaBelle's Mom]

Anyone think that since this came on so suddenly that it might possibly be a thyroid issue?