The Reverend Jack Russell did not have Jack Russell terriers - he had white-bodied fox-working dogs that, in his day, were simply called "fox terriers."

The term "Jack Russell Terrier" was coined after the Reverend John Russell was dead, and was used to differentiate small working terriers from over-large non-working Fox Terriers that by 1900 dominated the Kennel Club show ring and bench.

Today, the term "Jack Russell Terrier" is used to describe a wide array of dogs. Though there is a difference of opinion as to what is a "true" Jack Russell Terrier, it is revealing that the Reverend John Russell himself, never registered his own dogs with the Kennel Club and described his own dogs as being very different from those found on the show ring bench: "True terriers [my dogs] were, but differing from the present show dogs as the wild eglantine differs from a garden rose."

The simplest way to think about Jack Russell Terriers is to divide the entire lot of them into two groups as John Russell himself did: Those that actually work in the field, underground, to formidable quarry (what Russell himself valued), and all the rest - pets and show dogs alike.

Such a simple demarcation stood for more than 100 years, but ended in 1990 when The Kennel Club (UK) decided to add the Parson Russell Terrier to its rolls. The American Kennel Club followed suit in 2001, as did the United Kennel Club that same year.

While working terrier enthusiasts, such as John Russell, are principly concerned about function and do not much care about the color of a dog's nose or the lay of its ear, the show ring breeder is principly concerned about form.

In order to ensure that the value of show dogs is maintained and a sense of exclusivity and "purity" is maintained, Kennel Club registries are generally closed, and firm physical standards are crafted with the idea of minimizing the differences between breed members. The primary goal of a Kennel Club registry is "comformation" (hence the term "conformation show") and the working abilities of a dog take a second slot, if they are considered at all.

There are a wide variety of Kennel Clubs, each with competing registries and names for dogs claiming descent from the dogs of the Reverand John Russell. Some registries put no value on work at all, some value working dogs above all others, and some are largely conformation registries, but which give a small nod to the working side of the dogs in question.

The Jack Russell Terrier Club of America

The Jack Russell Terrier Club of America is the largest Jack Russell Terrier registry in the world. It is not a Kennel Club, but a breed specific-organization that organizes "trials" which pair conformation shows with performance events such as earthdog and agility trials.

The JRTCA actively promotes a working terrier, and its highest award is reserved for working dogs. The JRTCA breed standard recognizes Jack Russells as being from 10 to 15 inches (25 to 38 cm) at the withers, with a body length approximately equal to height. The JRTCA has an open registry, and does not register entire litters, but individual dogs at the age of one year of age and after photo and veterinary inspection.

JRTCA breed records indicate the size of every dog in their registry (useful for breeding dogs of the correct size) and whether those dogs have successfully worked quarry (fox, badger, raccoon, groundhog or opossum) under a JRTCA-certified field judge in a natural hunting situation.

The Federation Cynologique Internationale (FCI)

The FCI or Federation Cynologique Internationale, based in Belgium, added a small white dog to their rolls in the year 2000. This dog is called a "Jack Russell Terrier" by the FCI, but the breed is described as being "developed" in Australia -- a country the Reverand John Russell never visited. In 2001 and 2002, the United Kennel Club and American Kennel Club adopted the same breed standard (first created in Australia by the Australian National Kennel Council in 1990) for a dog they describe as a Russell Terrier.

The breed standard calls for principly white-bodied terrier 10" to 12" tall at the withers with a distinctly different silhoutee than the working Jack Russell terrier or Parson Russell Terrier. These dogs are sometimes referred to as an Australian Jack Russell Terrier. The FCI is not a registry and does not issue pedigrees -- it is a collection of national canine societies. Neither The Kennel Club (UK) or the American Kennel Club are affiliated members of the FCI.