Bedroom stinks of dog urine, I pulled up the carpet, how do I clean the back of the Carpet?

I just pulled up the carpet in one of my rooms, and the back is just blotches of dog urine, I pulled the carpet up because I can smell it. I have shampooed and cleaned with vinegar. Is there a way to clean the back of the carpet? We are in an apartment so I have to lay the carpet back down.