@Quercus:
IMO, and of course, probably mine alone, based on the description you have given here, I would euthanize this dog..period. There are very few physical problems that can cause this kind of aggression, and even if one is identified, they are difficult to medically treat.
I don't know what kind of techniques your trainer is using…but I would make SURE that they are not confrontational, as you will make the dogs behavior worse. Even a well respected trainer could be using inappropriate methods when it comes to aggression.
There is no ethical way that you can rehome this dog. If you choose not to euthanize, I think it is your responsibility to manage his behavior and try to improve his aggression. If you rehome him, he will bite the next family too.
Sorry to have such a depressing pov on this subject; I hope you find a solution.
I agree. Several years ago I had a similar situation with a rescue. I worked at a vet clinic when a stray hit by car lab mix was brought in. He was about a year old, skittish, and would growl at people from his cage. He had a broken hip among other injuries so it was hard to distinguish how much of the behavior was due to the pain. Another vet tech and I were able to build some trust with him and so my parents agreed to adopt him and work with him.
I don't know how your guy is with strangers but Homer, the stray, never trusted strangers but he bonded with my family. At first we had no problems with him. He was never aggressive with those of us he trusted until a few months later. Over the course of the next year he became progressively worse. He finally got to the point where he would turn on us all of the sudden. Things finally came to a head when my grandmother was visiting the house one day. Homer knew my grandparents very well. They "babysat" him at their house while my parents worked and had bonded with him more than anyone else. Homer was in the den by himself when my grandmother walked in the room. He jumped up with his hair standing up, and was growling and bearing his teeth at her until he had her cornered against the wall. My grandmother was able to move sideways against the wall till she could reach the door and get out.
After this, we called our vet who (again) consulted with a veterinarian who specialized in behavior. Based on the history, she felt like it was a serious fear based aggression and that it was doubtful that rehabilitation would be succesful. So we talked about it at home and decided to euthanize him. We knew that we couldn't risk him hurting someone one day. Even if we kept him in our yard or house all the time there was always a chance that he might get out by accident some how and that could have been very dangerous for our neighbors, their children or any other stranger he might encounter. It was one of the most difficult decisions anyone of us have ever made. I had to call the vet to set it up because my mom was so devastated about it.
I am so sorry because I do understand how you feel. Just from my experience I think that unprovoked aggression is very serious. I would try to help him as much as I could but if you ever get to the point where your afraid or uneasy of his behavior (especially when he strikes out unprovoked) than euthanasia is the right thing to do. In our case, it was the kindest thing to do for Homer. We don't know what happened to him before he came to us but he had obviously been pretty traumatized. That being said, I have heard of some success with aggression using clomipromine (i think thats how you spell it), an anti-depressant. I would NOT rehome him. First, the rehoming process is stressful and that could escalate his aggression. Second, if he ended up seriously hurting his new fosterers/owners than not only would you feel awful but there could be some legal consequences because you were aware of his behavior.
It is never easy whatever you decide. I'll be thinking about you guys.