There is a safe way to escape from the urine smell in shower drain you can solve this problem with no problems. At most pet stores there is a Pet urine stain and oder remover for your carpet the same stuff is safe enough for your drains and will kill the urine smell just pour the entire bottle down your drain.
Well, if you got kids make sure they don't pee into the shower. Another problem could be that the J trap in your shower is leaking. The j trap keeps water in the pipe right after the drain so that sewer gases can't rise.
In order to remove odor from your shower drain I would recommend using a product designed to remove clogs. This should remove anything the odor could be lingering on.
