Need help with GS randomly attacking my other dog they're normally best friends with
I've just suffered a dog incident just now and am still somewhat shaken, so apologies if this post is all over the place.
I have two female dogs. Tika is an all black german shepherd and Abby is an australian kelpie/shepherd. My problem is that every once and a while, Tika will for no apparent reason go completely ballistic and absolutely -rip- into Abby. It's like something triggers her somehow and she completely forgets who Abby is, blocks out the presence of any of us around(she completely ignores being told/yelled at to stop or even grabbed and pried off during this), and just goes berserk on her. People who have seen it have said it's like she momentarily becomes a completely different dog, and having just gone through it again up close I feel that's pretty accurate.
The attacks are short. I don't think any of them have lasted longer than 15-30 seconds, if that. And Tika clearly understands she did something wrong, at least after the fact. The moment she snaps out of HulkRage mode she goes very submissive "I know I just did something really bad" mode, staying low to the ground, tail between her legs, trying to find a chair to hide under, etc. But Abby is a much smaller dog and takes real and serious damage from these things that requires things like vet visits and stitches and antibiotics. I love Tika dearly, but I love Abby too. Does anyone have any idea what is going on with this?
For an example, here is what happened just now- I sleep upstairs. Both dogs were sleeping in my room with me on the floor near each other, being fine. I got up to use the bathroom. Tika followed me, Abby stayed snoozing in the room. I then returned to my room, Tika returned with me, walked over to the snoozing Abby and for no reason I can discern suddenly growled, grabbed her by the neck and started biting/shaking. Abby started yelping like crazy, I yelled at Tika to stop but she ignored me and I had to pry her off. When I got her off Abby's neck she went for her leg, and I pried her off that too, at which point she seemed to snap out of it and went quiet and went and sat in the corner looking guilty while I tried to tend to Abby. I'll have to take her to the vet tomorrow. Tika for her part has been put in a kennel/cage out on the indoor porch for the night.
I just don't get what's causing this. They were raised together, and 99.9% of the time they get along great. They play around with each other, hang out, follow me or my mom or dad around. They sleep comfortably near each other. And they are both great, loving, and obedient dogs who just want to be around their people and each other. Abby is generally submissive to Tika, who is much bigger than her, but other than occasionally laying down and letting herself be sniffed for a moment or two there isn't generally any problem. Tika has had no problems with any other dogs or other people, and when Abby has been recovering from the attacks Tika will sometimes even guard her to make sure she's ok.
So in summary... They're both sweet loveable dogs. I don't think they hate each other. I don't think anything was happening that should have triggered aggression. And Tika seems to very keenly know aggression is a bad thing and that she messed up when these things happen. Yet they keep happening? Thoughts?