Hmm. It may very well take a large team several hours to remove a kidney under ideal circumstances, Cecil, but its probably safe to assume that in this situation corners may be cut.
Veterinary surgeons don’t frequently remove kidneys (tumors or idiopathic renal haemorrhage being the only conditions springing immediately to mind which would warrant it) and so are likely to be a bit slower with that particular operation than they might be with other more familiar ones.
That said, one thing they’re very good at is ovariohysterectomy - bitch spay, in other words. The ovaries have their own fairly substantial artery (ie not the sort of thing you really want to miss), and are right next to the kidney. Time varies between 10 minutes and an hour, depending on the skill of the surgeon, the size of the hole he’s trying to work through (generally on the belly for better healing) and how big/fat the dog is. Given that dogs are generally longer in the relevant dimension than people, I reckon de-kidneying a person (ventral midline) would probably take me about 30-40 minutes - same as a collie.
<insert link to the sociopath thread here>
A lot of drugs such as GHB will last for quite some time although they could be easily topped up; this could be done by the surgeon himself if they’re not too concerned about sterility.
I’m not saying it happens (its even easier to harvest the organs from some poor south american no-one will miss) but it would be feasible.