they can still sound the alarm while not being in contact with the chickens. I think you need to fence in the birds. Are they in a secure run? If they free range, can you fence an area for them where the dogs cannot get in?
At present, the dogs represent a greater threat than raccoons, so you've got to deal with that first.
At present, the dogs represent a greater threat than raccoons, so you've got to deal with that first.