And 8 1/2 year old dog really shouldn't be THAT "old". But it all depends on the individual genetics and also the vet care. But I can't emphasize enough (altho I'll explain more in a bit) -- dental problems can make a HUGE HUGE HUGE problem in making a dog old before its time.
First off -- it probably HURTS to get on and off the bed. What SLR2Meg said about the bed is absolutley right on -- and it can be really demoralizing to a dog to LACK that closeness iwth you but getting up and down may just plain NOT be an option at this point.
So the dog comes up for some affection but knows it can't stay all night. It's very likely the dog ROAMS at night -- probably paces. If you stay in one place you get stiff if you're arthritic. So the dog gets down -- not because it doesn't love you -- but because of pain.
YES dogs can get dementia, or cognitive dysfunction ... a bit different than Alzheimer's but very similar. And particularly if you don't understand the pain cycle that IS life with arthritis, you are likely taking things as rejection that are simply pain related or changes because of age.
I have a little old lady peke right now who will take her nose out of her bowl and look up for air and then look around as if to say "hmmm, I was doing ... sumthin ... and ... it was a GOOD sumthin ... but ... hmmm, what WAS I doing???" -- the smell of food agitates her and she WANTS it but literally forgets where the bowl is. If I shovel food in her mouth with a spoon she's a happy happy girl!! She'll eat like a little piggy - -but she'd starve otherwise.
I've seen her walk 10 feet and suddenly stop ... and turn around .. and look both ways .. like "I know I was going ... *some* where .. but ... hmmm ... what WAS I gonna do?? Well, ... I'll just ... go ... THAT way ... "
Yes, they can actually forget what they were doing. It isn't that the dog isn't "smart" -- it's literally that age can cause some confusion. It may not seem possible but it WILL happen to you too, one day.
1. How long since this dog has had a dental? Much of what you are describing as to a standoffish behavior or acting like the dog may not want to be touched could simply be a bit of snarkiness resulting from dental pain. That will shorten their lives in a big way (it causes heart disease for one thing).
However -- when you say specifically when you grab the dog's collar he 'twitches' -- that's likely pain and it could EASILY be teeth. so ... someone grabs YOU and your mouth gets hit with immense pain ... how inclined are you going to be to have them yanking the collar around your neck? Wanna be close to them?? Noo -- take your hands away from my mouth buddy!! THAT HURT.
Remember, dogs are **stoic** -- even more so an independant breed like a husky. And they really don't age gracefully ... they don't WANT you to see pain (to a dog that is unforgiveable weakness - to let someone/something SEE your pain? That's way way way WRONG in the dog world). So they get grumpy because they hurt.
Usually a vet exam will tell the vet if the dog needs to be on some antibiotics FIRST and the some dental work done (maybe a tooth or two extracted -- can help a LOT).
2. A senior profile should be done every six months or a year at that age -- particularly for a dog that is showing some serious age-related signs. It could simply be incontinence -- but more likely there's a UTI (and old dogs get them more).
3. I don't mean this to sound mean -- but you have to put yourself in the dog's position. All of a sudden you aren't leader of the pack any more -- and when you are in pain you are ***vulnerable***. So where noises used to just make you want to bark, NOW they are a threat. You know you can't protect the house any more -- so now you also have to add fear.
SO YOU GET ANXIOUS!!! Yeah, separation anxiety can happen easily.
4. Honestly? I'd crate this dog or at least give it the biggest crate you possibly can or even a small room on the interior of the house -- a dog with separation anxiety? yeah -- because dogs are den animals and if, as I suspect, much of this is related to age, then give the dog a SAFE PLACE to be.
Radio or something for white noise -- to cover street sounds.
5. Are you giving anything for the arthritis? If you will email me I have an article I'll send you -- there are lots of things you can do for arthritis pain. If you are already giving an nsaid (and you need to be doing scheduled bloodwork because they are ALL hard on the liver and stomach) then giving a relaxant at the same time can often help it do *more* with less dose. (when you hurt you tense up -- tension increases pain because the joints then rub together even harder. So relaxing the joint helps that NSAID do more without having to work against the body tension.)
There are lots of other things including massage that can really help a great deal to relieve pain.
Also -- please don't discount acupuncture - it rocks for arthritis. I've had rheumatoid since I was a kid and acupuncture helps MY arthritis more than anything. (and yeah, that's how *I* know so much about how an arthritic being can feel!)
In addition, a vet who does TCVM (traditional Chinese veterinary medicine) can also give the dog some herbs which can help them SLEEP at night rather than wandering.