They, ahem, just take it from them. Thats what they had to do with Pouncer last night. He flat-out refused to pee, which I knew he woud because he won't pee when he's upset (I've tried to collect a pee sample from Pounce myself, and was unsuccessful. Even after he was locked in a room alone for 14 hours, he still refused to pee... at that point it was dangerous for him NOT to pee, so I let him roam free)