The smaller the dog and the more pure and concentrated the chocolate the more dangerous it is. Many children generously share the goodies they have collected with the family dog. It would be best to have a few dog biscuits or perhaps even a few pieces of pop corn for them to share with the dog instead of candy. Be sure to explain to the children why this is important. When children are in costumes that distort their features and body shape dogs may not recognize even children they know and like.
Dogs respond to and interpret information they receive through their senses in the following way.
Dogs trust and rely on their sense of sight the least of their all of their senses, they trust their sense of hearing next and will always rely on their sense of smell to make their final decision as to how they will respond to something. Even if the dog knows the child and the child speaks to the dog, the dog is unsure how to respond because what their eyes are telling them and what their ears are telling them are now in conflict. Once the child is close enough for the dog to smell and the dog recognizes who they are by their scent, that is usually the end of the problem. Unfortunately, many children are bitten before the dog recognizes them. If your dog is sight sensitive or easily upset by things you might consider keeping him in another room or in a crate during the hours you expect a lot of visitors at the door.