A terrier is a dog of any one of many breeds or landraces of terrier type, which are typically small, wiry, very active and fearless dogs. Terrier breeds vary greatly in size from just 1 kg (2 lb) to over 32 kg (70 lb) and are usually categorized by size or function. There are five different groups with each group having several different breeds.
Most terrier breeds were developed in Great Britain and Ireland. They were used to control rats, rabbits, and foxes both over and under the ground. Some larger terriers were also used to hunt badgers. The word terrier comes from the Middle French terre, derived from the Latin word for earth, terra. Terrier is also the modern French for "burrow". The Kerry Blue Terrier and Airedale are noted for tackling river rats and otters in deep water. Not long ago many terriers were also herding dogs, such as Wheaten Terriers. Different localities raised terriers suited to their hunting or vermin control needs. Terriers were crossed with hunting dogs, fighting dogs, and other terriers. In the mid-19th century, with the advent of dog shows, various breeds were refined from the older purpose-bred dogs.
The gameness of the early hunting terriers was exploited by using them in sporting contests. Initially, terriers competed in events such as clearing a pit of rats. The dog that was fastest in killing all the rats won. In the eighteenth century some terriers were crossed with hounds to improve their hunting, and some with fighting dog breeds to "intensify tenacity and increase courage". Some of the crosses with fighting dogs, Bull and Terrier crosses, were used in the blood sport of dog fighting. Modern pet breeds such as the Miniature Bull Terrier are listed by the Fédération Cynologique Internationale (FCI) under Bull type terriers.
Today, most terriers are kept as companion dogs and family pets. They are generally loyal and affectionate to their owners but can be "big characters" requiring a firm hand.
Based on a 2006 study, genetic analysis indicates that most terriers fall in the "modern/hunting" cluster of dog breeds developed from the same pool of ancestors in Europe in the 19th century. A few terriers are found in the "mastiff" cluster with Pomeranians, Labrador Retrievers, and other large-headed dogs, and the Tibetan Terrier is found in the older grouping of Asian and African dogs, along with the Pekingese.
In the eighteenth century in Britain, only two types of terriers were recognized, long- and short-legged. Today, terriers are often informally categorized by size or by function.
Hunting-types are still used to find, track, or trail quarry, especially underground, and sometimes to bolt the quarry. Modern examples include the Jack Russell Terrier, Rat Terrier and the Patterdale Terrier. There are also the short legged terriers such as the Cairn Terrier, Scottish Terrier, and West Highland White Terrier which were also used to kill small vermin.
The original hunting terriers include the fell terrier—breeds developed in northern England to assist in the killing of foxes—and the hunt terrier—breeds developed in southern England to locate, kill or bolt foxes during a traditional mounted fox hunt.
The various combinations of bulldog and terrier that were used for bull-baiting and dog-fighting in the late nineteenth century, were later refined into separate breeds that combined both terrier and bulldog qualities. Except for the Boston Terrier, they are generally included in kennel clubs' Terrier Group. Breeders have bred modern bull-type terrier breeds, such as the Bull Terrier and Staffordshire Bull Terrier, into suitable family dogs and show terriers.
Toy terriers have been bred from larger terriers and are shown in the Toy or Companion group. Included among these breeds are the English Toy Terrier and the Yorkshire Terrier. While small, they retain true terrier character and are not submissive "lap dogs".
Other descendants of the bull and terrier types, such as the Asian Gull Terr, are among the dogs still raised for illegal dog fighting.
Terriers range greatly in appearance from very small, light bodied, smooth coated dogs such as the English Toy Terrier (Black and Tan), which weighs as little as 2.7 kg (6 lb), to the very large rough coated Airedale Terriers, which can be up to 32 kg (70 lb) or more. As of 2004, the United Kennel Club recognized a new hairless breed of terrier derived from the Rat Terrier called the American Hairless Terrier.
Breed Groups are groupings of similar breeds of dog by kennel clubs; Breed Groups are not scientific classifications, and breeds included in a Breed Group will vary from club to club. The Fédération Cynologique Internationale, The Kennel Club (UK), Canadian Kennel Club, American Kennel Club, Australian National Kennel Council, New Zealand Kennel Club, and United Kennel Club as well as with the myriad hunting and pet registries may all vary in which breeds of terrier are included in the various Breed Groups that the club uses. The Miniature Schnauzer is placed in the Terrier Group by the American Kennel Club but not categorised as Terrier by the Kennel Club (UK), which places all Schnauzers in the Utility Group. Boston Terriers are true terriers although the Kennel Club also places them in the Utility Group, while the Canadian Kennel Club places them in the Non-Sporting Group. The American Kennel Club and the Canadian Kennel club recognise the Toy Manchester Terrier in the Toy Group, while the Australian National Kennel Council does not recognise the breed at all. The Tibetan Terrier and the Tchiorny Terrier (Black Russian Terrier) are terriers in name only and not related to the other terriers.
The organization of each breed group varies from club to club as well. The Fédération Cynologique Internationale (FCI) subdivides the Terrier Group into sections, including Large and medium-sized Terriers, Small-sized Terriers, Bull type Terriers, and Toy Terriers, while other major national kennel clubs do not subdivide the Terrier Group, although some terrier types are placed in the Toy Group by some kennel clubs, and some terriers are placed in other Breed Groups. Listed at the bottom of the article are all Terrier breeds organized by (FCI) section.