@Veterinari
Please do consider medication.
It's sad for me to read about dogs with clear sign of anxiety and cognitive decline that aren't treated.
Of course medication won't help in all cases but it can make a big difference in many.
Also treating any underlying pain is important as this contributes to anxiety
I'm aware that many vets aren't great at managing aging dogs - but pain relief and anti anxiety meds can help enormously along with enrichment and changes in husbandry .
Good luck everyone!
@Veterinari At what point would you recommend trying the selgian?
My boy is happy and calm, doesn’t get stuck or lose his way, knows his routine and expects us to stick to it - or else! 
He’s still sociable with other dogs on walks, always happy to say hello. Adores his food, snuffle and licki mats, kong wobbler and brain games (although I do have to help him cheat with some of those these days) enjoys his evening game of ‘chase me’ albeit slower and less manic than when he was younger.
He has a spinal issue which means he will very occasionally be unaware he’s pooing, but isn’t incontinent and still asks to go out regularly. He’s on Rimadyl, paracetamol and Gabapentin and we have seen big improvements in his mobility and comfort since adding in the latter eg, now curling up to sleep again and generally more active, plus he has regained tail movement.
BUT he doesn’t like being left and does get stressed if either dh or I have to go out, despite always being with at least two, if not three of our teen dcs, who are very invested and involved in his care. (This started when our other boy died last year and he has that tendency, as he developed separation anxiety when our previous dog died 8 years ago as well.) He doesn’t settle unless someone sleeps in the same room with him either.
He has occasional absent/senior moments where he seems confused and stands/stares, but these have improved a lot with med changes and the aktivait.
As I said up-thread, we work closely with the vet and they have noted that he is still engaged and ‘present’ at appointments. The vet has been brilliant and given we monitor closely and update every month, I hope would guide us if they felt something like selgian might help. In your opinion though is it better started early or when signs start to escalate?