I recently had one of my girls develop Marek's. It became clear after several weeks of vet trips, taking very good care of her inside our home etc. that she was just getting weaker and would eventually succumb to a bad death so I decided to end it. I didn't want to take her to the vet again and have read about the break-the-neck method but there's just no way I could do that to her. I'm aware of the CO2 method and I know it's widely used but I just can't imagine it's an easy death. As noted in another post here, the brain is aware when it's CO2 overloaded and the "trying to breathe" reflex kicks in. To me it almost sounds like awake suffocation. So, instead I've read a lot about substituting Nitrogen because it isn't supposed to trigger the same reflex since we live in a Nitrogen-Oxygen atmosphere the brain doesn't "think" anything is abnormal until it's too late. Nitrogen is also easy to obtain... any gas supply store or welding supply store will carry small canisters of it. I picked one up at my local supply for $130. The majority of this is the price of the cylinder which is refillable. I figured that since I have 6 chickens (and plan on additional in the future), this may not be the only time I'll have a sick chicken needing euthanasia so the cost would be fine since I estimate there's enough gas per cylinder for at least 6 uses. I took a big plastic tub from Target and made it airtight with the exception of one hole I drilled in the side for the hose coming from the nitrogen tank and four smaller holes in the bottom to vent out any remaining oxygen (nitrogen is lighter than air so the remaining air will vent from the bottom). I put the whole thing in a big plastic bag and after putting my sick girl in the plastic tub and put the airtight lid on it, sealed the bag. This kept the nitrogen recirculating (and also allowed me to vent any remaining air out as the bag filled up). I've attached a photo. I put my sick girl in there and turned on the gas. I would say it was all over in under 5 minutes. At one point I did hear flapping at the very end (which was hard to take because from other threads here you know that's the end). I was surprised about that because I thought that she would succumb and not regain consciousness. Maybe that's an autonomic reflex? I don't know but I kept the gas on for about 15 minutes just to be sure and didn't open the bag or container for a half hour. I wanted to make sure before I buried her that there was no chance she could just be unconscious and could come alive later etc. After it was over I took her out and waited in the normal air for about a half hour again to make sure I felt she was cooling down (no body heat being generated). Again, this is just my experience. I did work and again, if you're facing this decision and don't like breaking the neck, it's an option. Note that in reading other posts of people who used CO2, I heard the peroxide/baking soda and the dry ice method being used. To me the dry ice is hard because you have to obtain it too and make sure neither you nor your chickens touch it. I also read about one guy who hooked a hose to the tailpipe of his car. Please don't do that because what comes from the car is not pure CO2 but a mixture of CO2 and burnt hydrocarbons. You know if you go behind a car near the exhaust and breathe in the vapors you want to cough. That's because the unburnt hydrocarbons irritate the lungs. Don't do this to your chickens, it hurts. You need pure CO2 (or as I did it, pure Nitrogen). Remember they're your pets and deserve as quick and painless death as possible. Feel free to email me if you have any questions on the bin or Nitrogen process I used. My email is : firstname.lastname@example.org Bless our chickens!