This case has been somewhere with cats...
You can try Febreeze, you can try NilOdor, you can try covering it in bicarbonate of soda, leaving it for a few days and then vacuuming it off ... but it's likely that eventually you'll wanna get that drycleaned :/
Go to a pet store. Get some of the urine cleanser which is specifically a bottle of enzymes. The enzymes break down the proteins in the urine which make it so persistent.
Alternatively, you could try mixing up a little meat tenderizer solution (try to find without salt) or contact lens enzyme solution. However, I think the latter is likely to be too weak, and there's no telling if a DIY enzyme will stain. Presumably the bottled products have been tested on fabrics.
Worst case, just buy a pound of papain powder, throw it in the washing machine with the case, and let it soak for a couple of hours.
http://www.takeherb.com/product.asp?PID=40298
BTW, the above works great mixed with sterile saline as a substitute for contact lens enzyme solution. At least it does for me on my hard gas permeable lenses. They stopped selling the little tablets around here and try to get one to use a super-expensive solution, and a ridiculous amount of it per use.
