Halloween costumes are fun and are meant to disguise our normal appearance. Dogs do not understand this change in appearance and may become frightened.
Costumes that change the way a person walks, stands, or general appearance may cause a dog to react differently than usual even with those they know.
Keep in mind that children on Halloween night are excited and doing their best to be scary. This is not a fair or safe situation to put even the best of dogs in. Even the normally terrific tolerant family dog can find this night hard to handle.
Along with costumes being frightening to a dog there are some that may become interesting too. Swords, tails and dangling things may be fun for an excited dog to chase and toddlers certainly won’t appreciate that.