>>1793458OP here. I didn't leave it in the cage. This story is disturbing, fair warning.
First I tried to do the carbon monoxide thing with a tailpipe. I wrapped the cage in a tarp, canvas not plastic so it could touch the hot metal, and bunched and twisted the opening together, then wrapped that around the exhaust. It was a little loose but I didn't think that would matter. So I turned the car on and left it going for ten minutes.
When I came back the raccoon wasn't dead, it was just hyperventilating and the cage was hot. This wasn't working and was just making it suffer more. I didn't have any more bullets for my varmint rifle, which was why I phrased the OP that way, so I left the raccoon in the cage on some grass while I went to the store for ammo.
An hour later I took the cage to one of my outbuildings, loaded up a 22 short rifle and shot it. I thought it was going to bleed out and left it for 15 minutes, but when I came back it was still breathing. So I shot it again. Then again. I don't know if it was the low caliber or I just had shitty aim but it was still alive, lying there.
I decided to try something I read online, which is that if you make an imaginary line from the right eye to the left ear, and the left eye to the right ear, then shoot the intersection, that'll get any animals brain. I did that, and it worked, but it didn't destroy enough of the brain for it to be instant. All its muscles seized it made a horrible sound. It scared me. But it did stop moving, in an awful unnatural position. All that was left to do was carry the cage near a river to dump the body.
I cried as I came back, and a few more times since then, thinking about how much unnecessary pain I put it through by fuckups. The day after I went and looked at the body and it gave me some comfort to see it lying more naturally, finally at peace. That's how fucked up I was about it. The guilt was horrible.
1/2