[Q]

I have to cull a week old chick because it has splayed legs.  I thought I had improved it with splints but it has got dramatically worse.
I think the other chicks have been jumping on it as the weakest one.

Not pleasant but whats the best & least painful method?

[Marches Farmer]

Have you tried putting a 1cm strip of adhesive tape around the legs to make a hobble, leaving the width of the top of the legs plus about 1cm  slack?   I find this generally works in about 3 days.  If it's getting bullied I put it in a cardboard box under the lamp, with its own feed and water, placed so that it can get away from under the lamp if it's too hot.  If this doesn't work there's generally another, unseen,, problem with it.  I use Semark pliers for culling - handling very gently I put the "blades" between the vertebrae and snap them closed and backwards.

[Q]

Thanks MF, the splint was on after day one and was on for 2 days - it looked like it was improved but today 3 days later it was hardly able to walk with its leg at a very awkward angle and dramatically worse than yesterday..
I have culled it now almost identically to how you said.

Never easy.

Sorry little chick but it was for the best.

[Clansman]

with small chicks I usually place my thumb on its neck and push hard it against a blunt edge to break the neck.