This isn't my first rodeo with rescue dogs, my first ever dog was an 'underdog/hard to home' and in a rescue for around 4 years before I adopted him. He was very reactive and unfriendly with other dogs from day 1 (which we were told about) but he was always very good with people. In the end we did manage to socialise him with other dogs(our hand was forced as a close relative passed away and wanted us to take care of their dog).
We adopted a rescue dog in May of this year, after sadly losing both dogs during the past couple of years, (due to old old age). She's bluntly, been extremely reactive, to everything, the entire time we've had her and I'm starting to feel like a failure to have not made more progress in the time she's been with us. She snaps and snarls at people, other dogs and animals, but is always muzzled in public, of course. She did get particularly irritable just before Christmas, so we've just taken her to the vets to get her checked out for any pain or injury. I'd previously highlighted a manky/rotten looking tooth, which I thought may be causing issues, but two vets have been seemingly unconvinced it's causing her that much pain. We will have the tooth examined/cleaned/extracted in the hopes it may be the root of the issue, but if it isn't I'm not sure how to go forward. I can see her potential, but also feel like she maybe isn't suited to our household, for some reason I can't ascertain. I know all dogs are individuals, but to regress in behaviour after 6 months feels unusual. We have one other resident dog who is fortunately ridiculously passive to her snippy behaviour. Does anyone have any reassurance that we perhaps need to give her more time to settle?