Sleeping cats

the situation: a vet is taking care of an injured cat and he says: If it does not pee by lunch time "I'll have him down and put a catheter in".

Well this "I'll have him down" what exactly does he mean? make him lie down? bring him down from somewhere, or is it some slang?

I'm lost and puzzled my friends.

and thank you of course!!!

I would imagine that the vet means that he'll 'have him down' to the operating theatre.

Or put him under anesthetic. I wouldn't like to put a catheter in a cat that was awake.

Don't confuse this with 'We had our cat put down." This means the animal was suffering and was painlessly killed by a vet. That is not the meaning here!