Companion dog in the context of American Kennel Club

A working dog is a dog used to perform practical tasks, as opposed to pet or companion dogs.

Definitions vary on what a working dog is, they are sometimes described as any dog trained for and employed in meaningful work; other times as any dog whose breed heritage or physical characteristics lend itself to working irrespective of an individual animal's training or employment; and other times again it is used as a synonym for herding dog.

The Golden Retriever is a Scottish breed of retriever dog of medium-large size. It is characterised by a gentle and affectionate nature and a striking golden coat. It is a working dog, and registration is subject to successful completion of a working trial. It is commonly kept as a companion dog and is among the most frequently registered breeds in several Western countries; some may compete in dog shows or obedience trials, or work as guide dogs.

The Golden Retriever was bred by Sir Dudley Marjoribanks at his Scottish estate Guisachan in the late nineteenth century. He cross-bred Flat-coated Retrievers with Tweed Water Spaniels, with some further infusions of Red Setter, Labrador Retriever and Bloodhound. It was recognised by the Kennel Club in 1913, and during the interwar period spread to many parts of the world.

The German Shepherd, also known in Britain as an Alsatian, is a German breed of working dog of medium to large size. It is characterized by its intelligent and obedient nature.

Its historical role was as a herding dog, for herding sheep. It has since been used in many other types of work, including disability assistance, search-and-rescue, police work, and warfare. It is commonly kept as a companion dog, and according to the Fédération Cynologique Internationale had the second-highest number of annual registrations in 2013.

The Labrador Retriever, also known simply as the Labrador or Lab, is a British breed of retriever gun dog. It was developed in the United Kingdom from St. John's water dogs imported from the colony of Newfoundland (now a province of Canada), and was named after the Labrador region of that colony. It is among the most commonly kept dogs in several countries, particularly in the Western world.

Labradors are often friendly, energetic, and playful. It was bred as a sporting and hunting dog but is widely kept as a companion dog. Though content as a companion, these dogs are intelligent and require both physical and mental stimulation. It may also be trained as a guide or assistance dog, or for rescue or therapy work.

The Yorkshire Terrier, also known as a Yorkie, is a British breed of toy dog of terrier type. It is among the smallest of the terriers and indeed of all dog breeds, with a weight of no more than 3.2 kg (7 lb). It originated in the nineteenth century in the English county of Yorkshire, after which it is named. The coat is tan on the head and dark steel-grey on the body; no other colour is accepted by either The Kennel Club or the Fédération Cynologique Internationale.

It is a playful and energetic dog, usually kept as a companion dog. It has contributed to the development of other breeds including the Silky Terrier, and also to cross-breeds such as the Yorkipoo.