For the dog experts to help you, you will need to go into more detail.

What kind of back problems?

How old is your dog?

There are different treatments for different problems, we will need a little more information.

Has the dog been to a vet or you just know there is something wrong with its back?

Until we know exactly what is wrong all I can recommend is making sure your Doxie doesn't jump, if he sleeps on the bed or the couch get some steps for him so he doesn't have to leap.
If you have stairs leading to your backyard then think about installing a ramp.
The less jarring that is done to their backs the better.