David,
It is very difficult to control. If you know the specific places where is is contaminated you can soak it with urine neutraliser and then use a water claw to suck it out, even then you may not solve the problem as it can be in the underlay and have been there for quite some time, so I wouldn't be giving any guarantees.
You could also fog the room as the smell may be on the walls etc.
Hope this helps.
Simon