Sooo... I didn't read all 73 pages, but seems to be consensus here is slitting/cutting/etc. My question is, has anyone considered a pellet gun? By pellet gun I mean an actual .177 air or spring gun, 700fps, etc, not a Red Ryder BB gun. The things are capable of killing coyotes, and are more than capable of instantly killing a gopher when popped in the head.
Obviously there are legal concerns, many places consider pellet guns as firearms and as such are subject to those regulations, not to mention will do a LOT of damage to your foot should you miss lol, BUT a quick shot to the head would be pretty much instant and painless... and probably messy...
But... seems to me it's more 'humane' than slitting their throats and letting them bleed out.
Might even look into firing a larger caliber blank against their head, then concussion from a blank can be very damaging.