A working dog is a canine working animal, i.e., a type of dog that is not merely a pet but learns and performs tasks to assist and/or entertain its human companions, or a breed of such origin. In Australia and New Zealand a working dog is one which has been trained to work livestock, irrespective of its breeding.

Within this general description, however, there are several ways in which the phrase is used.

Although most modern dogs are kept as pets, there are still a tremendous number of ways in which dogs can and do assist humans, and more uses are found for them every year. The following list provides an idea of the versatility of dogs:

Dogs are commonly used as search and rescue workers in cases of lost people and disasters. The St. Bernard was historically used in Europe in the case of avalanches and lost travelers. Search dogs are used in lost person searches each year saving human lives. Several breeds of dogs were used during World War I to locate wounded soldiers in the field. Several cities in Italy are experimenting with working dogs as rescue swimmers. In this situation, a strong and well-trained dog is equipped with flotation devices and dropped in the water near a floundering swimmer. The swimmer then grabs onto the dog, and the animal tows the swimmer to shore. The Newfoundland has long been used for water rescue, not only on shore, but from fishing boats as well.