I actually give my 12 year old a special senior plus vitamin that I researched online and get from Drs. Foster & Smith but only for one reason. She was completely paralyzed when she was 3 and had spine surgery for a herniated disc. Last year she started having her back legs knuckle under again and couldn't even walk a hundred feet up the road. The vets wanted to do surgery on her again. We had read some medical research on the vitamin B groups helping with nerve damage so started her on the vitamin with the most amount of all the vitamin B's we could find. I also switched her to Innova Senior Plus dry food last month, which also has an extra amount of the Vitamin B groups in it.
She now can walk almost a half mile and runs all over the back yard, barking like a puppy. I haven't seen her this happy in years. I can't swear it's the vitamins, but she gets one every day and it's chewable and bacon flavorered and a lot cheaper then surgery so I will keep giving it to her. (Of course, the more she can walk, the more I walk her so the extra exercise helps build up her legs and I have taken that into account when I consider whether or not it's the vitamins working. )