I was going to post a much more concise reply until I was beaten to it.
Phenobarbital's the stuff which Exit International reccomends people smuggle into Australia from Mexico before they get too infirm to get it so they can go a bit of the old euthanasia.
I sincerely hope the scum who strangled that chicken dose up without researching it.
It's not Phenobarbital, thats quite weak, its pentobarbital. Which they use for euthanasia in humans and in anaethesia along with midazolam and fentanyl in hospitals