sentence: Dogs are used by humans for many different things, for work and as pets.
sentences_before: It has been domesticated by humans for a long time. It was the first animal ever to be domesticated.
sentences_after: They are a popular pet because they are usually playful, friendly, and listen to humans. Thirty million dogs in the United States are registered as pets. Dogs eat both meat and vegetables, often mixed together and sold in stores as dog food. Dogs often have jobs, including as police dogs, army dogs, seeing eye dogs, fire dogs, messenger dogs, hunting dogs and sheepdogs.
concept_name: dog
headings: Dog
categories: Dogs