i kno ive already spoke to you bout this, i dont kno how to do it :S, but i wanted to say im sorry for your lil degu :(. I think id wait and take it to a vet, get it dont properly.
also is breaking the neck the only way? that is really horrible for you to do. i kno i sound even more horrible but is thereb a humane way of 'crushing' the poor lil thing, not to sound in sensitive and like i dont give a f***. i just thought that wud be kinda more humane then breaking the neck of the animal.