We had exactly this problem, except our Casey (the aggressor) never broke skin in his attacks. A year and a half after the aggression started, Casey had two grand mal seizures. I took him to the neurological ER about a half hour away, and they diagnosed him with a brain tumor. Treating the brain tumor lessened the attacks until toward the end of his life. Here is a link to my posting here asking for help when the aggression became a problem, then an update after he died several years later. You may find the suggestions that were given to me to be helpful to you.

Here is a link that might be useful: Casey's story

This is a pretty serious situation, as you know. You are probably best off consulting with a behaviorist/trainer. Find one that works will positive reinforcement only, no talk of dominance, pack hierarchy, punishment of any kind. That kind of talk has been debunked, and that kind of training will not help your reactive dog. The ASPCA has a page on finding professional help for your dog (I'll try and post it for you). I also second thoroughly investigating for any kind of neurological issue. I would suggest keeping them separated until you have some answers. Best of luck with this difficult issue!

Here's the link to that website:
http://www.aspca.org/pet-care/virtual-pet-behaviorist/finding-professional-help

This post was edited by sarabera on Tue, Oct 29, 13 at 23:58

Im sorry you are having this problem. This is a tough one, because you never know when your little one is going to go off. My suggestion is
1. Start basic training ASAP
focus on sit, stay and leave it. Train EVERYDAY for an hour a day. MINIMUM
2. You might want to consider a muzzle while you are out walking.
3. Be certain when you start your walks to take charge, and to maintain calm (no asking the dogs if they want to go for a walk - waiting until they are calm before walking out the door)
4. This is the hard one. Try to anticipate your dogs moves. Often times you can tell before your dog is going to go off. Ears go up, body goes tighter. You can put your dog in a sit stay and REDIRECT your dogs attention to you by holding a treat by you and asking your dog to focus on you (either until the critter or situation passes)
5 you can keep your rambunctous furkid on a shorter leash, and walk her on one side while walking your other dog on the opposite side of you - minimizing the ability to attack your other furkid when something happens to excite her. Hope some of these help, Good luck

Hi, I am currently having very similar issues with my two dogs now. What did you do to remedy the situation? My girls almost killed eachother last night and I'm at a loss for what I can do to remedy the situation

When a friend had to bring a sometimes aggressive dog back into her home after it bit a child in its new home, she feared for the other dog. She consulted with a behaviorist who told her (of course) that she could never let the dog near children again. The we worked on getting the two dogs used to being together again. What we did was bring the biter into the home only when the other dog was present, then I would come over and the two of us separately trained the two dogs in the same general area, where they could see each other but not interact, for maybe an hour. Training = treats = good feelings. So then we took the biter away again. Thus, every time he saw his sister dog, he was flooded with treats and good feelings because he was "playing" training games. After a few weeks of doing this frequently, he was brought back home to stay. I don't think he ever got aggressive toward the sister dog again. As a matter of fact, she got her female dominance going and used to push him around. He allowed it, as he should. He was never safe toward children, though. Both have passed on. We are getting old!

Your girls almost killed each other last night....You know I missed that in reading your post. Some females are just too dominant over others. I had a fairly dominant female lab/husky mix who would get into it with the dog park's founder's lab, who was also a dominant female. Luckily, she knew dogs well - a lot more than I did - and she decided that her dog really was not appropriate for the dog park. I always carried water in my hand, since dumping it on a snarly pair of dogs always stopped the issue. But these were minor snarly, snappy fights with no blood. If you really almost lost your dogs last night, that is very serious behavior. Most fights I have witnessed drew no blood at all.

Are your females spayed? Are puppies involved in this fighting behavior? You must know what to do before you start having breeding females together. (Ethical issues put aside from this discussion.)

If these are not your issues, your consultation with the behaviorist may result in separation. Some females do not accept other females. I knew to only get males when I had Megan and wanted to add a dog to my home. It was her behavior at the dog park that taught this to me, though. If I had not seen her with other dogs, I would not have known.

They are both spayed, and we were all been a happy family for a year before this happened. I recently moved in with my friend and we're now living in a condo instead of a house. I've been taking her on longer walks, but it hasn't fixed anything yet. They're both cuddled up on the floor right now. They love each other, but their fights seem so sudden, unprovoked, and they have been getting more and more serious. The thought of giving one up kills me. They both came from terrible backgrounds, but they've never shown aggression before a month ago

Try to make note of when and where it happens. Time of day, circumstances, physical properties of the space where they blow up, anything can be helpful to your trainer. With my Casey, he initially went after Bina mostly in tight spaces. Later, he was usually guarding the room and did not want her to enter the family room or the space around me.

Once you figure it out, you can watch for it and distract the dog before it happens. We used to yell with lots of Whoop! Whoop! loud noises to startle Casey out of his fixated trance, then get his attention on us, not Bina. But Casey had a brain tumor and we were fighting against whatever damage it was doing to his brain. Your situation may be completely different, so that is why you need an expert to help you figure out what is happening. We finally decided not to leave any chew toys out at all, since Casey could decide to guard them at any time, for instance. Things changed over the course of the three years he had his tumor. Toward the end, he could not follow his training and control his impulses. He was all ID, a psychologist would say. If he wanted to know what was on the counter, he jumped up and looked. If he wanted to eat something on a counter, he jumped up and took it. We had gates everywhere and had to be perfect about using them and leaving things in his reach.

I have known others who had two dogs who were incompatible and could not be together. They managed the gates in their home to keep the dogs apart. They also arranged their lives to spend time in the spaces of both dogs, so neither was neglected. It can be done, but it is difficult!

First, save your money, and find that trainer to come to your house and work with the dogs and figure out what the problem is.