[anonymously]

Five is young. As far as supplements go, most of them are a scam and a waste of money.
You may be better off saving your money for other age related issues that come up.

Fish oil is the only one I use for just general issues…
http://skeptvet.com/Blog/category/herbs-and-supplements/

PS: Don’t underestimate genetic back concerns….use doggie steps if need be and don’t allow the dog to jump in and out of high places, like the car.
I just went through this with a poodle mix that has a long (dachshund like) back. She does not have short legs.

http://www.pbs.org/wgbh/frontline/film/supplements-and-safety/