Our older ACD became a barker after the loss of her life long companion. We tried a citronella collar with no useful improvement. She very quickly worked out what it was about and went and pushed the canister into the lugs of the tractor tyre and quietly woofed till she emptied it and was then free to bark again. The reason we tried a training collar is that my OH is disabled and it was hard for him to get to her everytime she woofed. The introduction of a puppy and correction when she woofed for no reason stopped her inappropriate behaviour. She is a rescue and could not cope with being alone - which is why she was barking. It is important to find the reason for your dogs inappropriate barking, if possible, and do something to rectify the situation.