We have an old Jack Russell who is about 16,  I rescued him back in 2004.  He is basically very healthy and had a check up at the vets recently when he had his yearly booster.  He has never had much wrong with him - typical JR, tough as old boots!  However recently we have noticed some changes in his behaviour.  He does a lot of mindless barking for no reason but the most worrying thing is that over the last week or two he has woken up about 4 or 5am, scrabbling madly at at the back door, trying to get out.  He sleeps in the kitchen with our other dogs and has always been good at night.  Sometimes we have to get up to him several times.  Although he goes out in the garden each time he doesn't seem to particularly need to relieve himself.  It is almost as if he wakes up and gets into a panic.  So I am wondering if this is a form of doggy dementia? I really don't think that he is desperate for a wee or poo and he has always been let out last thing at night.  I wonder if anyone else has experienced odd behaviour in oldies?

We had a Rott who, when she got to about 11½, started to get times when 'lights on but no-one at home', The Vet suggested we try her on Activate, which definately improved things. We finally lost her at 13¼ from general old age - spleen removed at 10, low thyroid function, arthritis etc.
We had the first lot from vet to try and then got a prescription to get on line as she wasn't insured.

Assuming there's nothing triggering these episodes - a strange new noise, a rodent around the back door, or even pain can cause some really odd behaviours (and not necessarily with additional obvious symptoms) - then I'd have a word with the vet about supplements such as Aktivait as tatty-ead mentioned.

I will make an appointment to see the vet, thanks.