Smaller than the English springer spaniel, the cocker spaniel is a dog bred especially for hunting along hedgerows and thick cover.  It faces this cover without hesitation and, in a country such as Ireland with its many areas of natural cover still existing, the breed is enjoying something of a revival in that country.

The name ‘cocker’ is derived from the quarry the dog was primarily bred for hunting, the woodcock.  This wily bird favours the rhododendron and the blackthorn thickets that still abound in Ireland.  The smaller proportions of the cocker or ‘cocking’ spaniel make it ideally suited for hunting woodcock in such cover.

This breed, like many others with origins as working dogs, has some genetic lines that focus on working-dog skills and other lines that focus on ensuring that the dog's appearance conforms to a breed standard After World War II, Cocker Spaniels bred for pets and for the show ring increased enormously in popular appeal, and, for a while, was the most numerous Kennel Club registered breed. This popularity increased the view that all Cockers were useless as working dogs.

Today, this breed is experiencing a resurgence in usage as a working and hunting dog. Dogs from working lines are noticeably distinct in appearance. As is the case with the English Springer Spaniel, the working type has been bred exclusively to perform in the field as a shooting dog. Their coat is shorter and ears less pendulous than the show-bred type. Although registered as the same breed, the two strains have diverged significantly enough that they are rarely crossed. The dogs that have dominated the hunt test, field trial and hunting scene in the United States are field-bred dogs from recently imported British lines. Working-dog lines often have physical characteristics that would prevent them from winning in the show ring. This is a result of selecting for different traits than those selected by show breeders.