
I use
salmon oil for all my dogs of any age, but it is beneficial especially as joint problem prevention and in older age.
My older guys (from about 7 years on) I also give a
glucosamine/chondroitin/MSM supplement. I use the Liquid Joint Care from Holland & Barratt. I am finding this very effective. My 11-year old lurcher doesn't show any signs of joint problems yet eventhough he had knee surgery two years ago.
And last but not least, from about 10 or so, I also give
CSJ Turn Back Thyme herbs, which are just a general conditioner and support for older dogs.
If there are already joint problems as in your dog's case, I also give
turmeric and
devil's claw to help with the inflammation and pain (my 8-year old saluki gets that due to a damaged disc in his back). I have found particularly the turmeric extremely effective and has enabled my boy to stay off pain killers for over a year after he was in so much pain last year that I thought we'd need to give him drugs. With devil's claw, you have to be careful as it doesn't always go very well with NSAIDs.
A Bioflow collar might be very useful too and my guys with joint/spine problems wear them.
In addition, McTimoney chiropractic can be very helpful (and I am sure it helps my two guys stay mobile despite their age/back problem) as can hydrotherapy!