bell to hang on door for dog - HEALTHY
MSN: Train Your Dog to Ring a Bell to Pee: A Step-by-Step Guide Training a dog to ring a bell to signal that they need to go outside to pee can be a useful and convenient solution for pet owners. This training method involves teaching your dog to ring a bell ... Train Your Dog to Ring a Bell to Pee: A Step-by-Step Guide For example, he struck a bell when the dogs were fed.
Context Explanation
If the bell was sounded in close association with their meal, the dogs learnt to associate the sound of the bell with food. After a while, at the mere sound of the bell, they responded by drooling. Another possible origin is the one this page advocates: