Do you have a mattress pad that is waterproof?
Maybe you could call where you got the mattress or the mattress company has a website, get on there and see if there are any suggestions to take the urine smell out of your mattress.
I have tried many things to take the "doggie smell" out of my house. A few things that have helped are those Yankee Candle plug in's. When I burn candles that helps to take the smell away ( mostly anyway ). I am sorta @ my wits end also cause if I don't do the above everyday, my house smells like dog.
Good Luck.
