hey guys,
His last check up at the vets was about a week ago. He had his deworming and update of all his shots, so that rules out his being physically unwell or uncomfortable.
An abused dog will always have sensitivities to feeling threatened and a lower tolerance threshold, so this comes as no surprise really. But I was reading your posts and wondering about vaccines to myself when you just offered it here - and just a week ago!!! AND you say "ALL" - sounds like he got more than one at one time - something the AVMA doesn't even condone anymore.
So let me explain - if he got one of the neurological vaccines: distemper or rabies - then behavioral changes are common with these. These two disease are neurological diseases and by definition attack this system - the vaccines are designed to do the same thing obviously (they contain the disease) - so neurological side effects are possible. If you do some research, you can find several studies that document the known side effects from vaccines, and these two inparticular have a long list of aggression and other behavioral side effects. Rabies is best known for behavioral problems as side effects.
So now let's back up: we have a dog with abuse in his background who has been working to overcome his emotional trauma and has a naturally low threshold for defensiveness. Then he gets substances injected that are designed to target his neurological system, and if they overwhelm his immune system, can result in the exacerbation of behavioral issues or onset of aggression - I have to say that you have a strong likelihood of seeing increased aggression with further vaccines and that you should keep a journal tracking substances injected with behaviors you notice in an effort to identify.
I recommend you do some research on vaccines and their cautions as well as possible side effects so that you understand what is possible in the future should you vaccinate again. Vaccines do cause discomfort, pain, swelling, internal inflammation, auto-immune reactions, anaphylactic shock, brain swelling and a host of other problems so please never assume they are benign substances. Also understand that once a dog has had his initial puppy shots, he is good for life just like we are....I haven't had a vaccine in 30+ years. Mounting vaccines do not provide more protection - you either developed immunity upon exposure or you didn't - the immune system doesn't need reminding.
I think this is a medical problem mounted on a behavioral problem and will require a multi-pronged approach in an attempt to resolve.