A gun dog is a dog which has been trained to assist hunters. There are several different types of gun dog, trained to perform a variety of tasks ranging from flushing out game to fetching downed birds. A high-quality fully trained gun dog can be very expensive, reflecting the work which went into the training and breeding of the animal, and these dogs are not pets: they are working animals, with centuries of tradition behind them.
Setters and pointers are dogs which are trained to scent out game and then freeze, typically in a distinctive stance, to alert the hunter to the fact that a bird is nearby. Depending on the hunter's technique and preferences, the dog may be ordered to stay while the bird is brought down and then sent to pick up the body is a bird is downed, or the dog may be ordered to flush the bird, scaring it out of hiding so that it can be shot. These dogs have a very keen sense of smell paired with lean, muscular bodies which give them the endurance necessary to spend a day in the field.
Flushers are gun dogs which actively flush out birds, first seeking them and then attempting to frighten them into taking wing. Flushers are used to hunt birds like pheasant and grouse, which can be slow to take flight, and they are also used to herd birds as they attempt to escape the hunters. Spaniels are the breed most typically used for flushing.
Another type of gun dog, known as a water dog, is trained to deal with downed waterfowl. Water dogs enjoy swimming, and have coats specially adapted to help them stay warm in cool weather. One well-known example of a water dog is the standard poodle, which was originally bred to retrieve fowl like ducks and geese.
Finally, retrievers are trained to retrieve birds after they have been shot. These gun dogs are very patient, able to sit for hours in silence while their masters wait for prey, and they also have very keen eyesight, allowing them to mark the precise spot where a bird has fallen so that they can collect it quickly.
Training a gun dog takes work. The dog must be taught to be safe around guns, and it must learn a complex series of commands, most of which are visual, which can be used to control the gun dog in the field. Gun dogs also learn to be patient, as a restless or noisy dog could scare game away. Highly trained gun dogs sometimes compete in dog shows, allowing their trainers to showcase their unique abilities.