The first Jack Russell terriers were bred by Reverend Mr. John Russell. This Parson was born in 1795 and grew to be a hunting enthusiast.  Whilst at Oxford University he bought a small white and tan terrier bitch called Trump. She was the basis for a breeding programme to develop a terrier with high stamina for the hunt as well as the courage and formation to chase out foxes that had gone to ground. He also wanted to remove the aggressiveness that in other dogs would result in their harming the fox. This destruction was considered unsporting. This specific breed is now known as the Parson Russell Terrier, and is around 32-38 cm at the withers.

Reverend john Russell died in 1883, but the line of terriers he developed was already well respected and his dogs were taken on by other hunt enthusiasts.

It is speculated that the first split between the varous types of Russell terriers may have occurred early in their history, with dogs being sold by the sister of John Russell's kennel man. She described them as "Jack Russells" but it is not confirmed they had been part of the line of terriers developed by John Russell.  Instead they may have been working terriers with shorter legs and of mixed heritage. Near to 70 years later, the secretary of the Parson Jack Russell Terrier Club bred a strain of terriers specifically for for badger digging. These needed the brave character and endurance of the Jack Russell Terrier, which were crossed with Bull Terriers to give a stronger and harder dog with shorter legs than the original type. Again these were described as "Jack Russells" and were 25-30 cm at the withers.

Development through Breeding

Along with these changes the Second World War had a great impact on the breed. Sporting dogs were needed less and the numbers of working Russell terriers were drastically reduced during these years.

The original working Russells often became family dogs and were crossed with other popular family dogs including Corgis, Chihuahuas and terriers such as the Fox Terrier and the Staffordshire Bull Terrier. These crosses resulted in changes in form and function and led to a new type of short-legged terrier with a variable conformation. It is this form of the descendants of Trump that are now known as "Russell Terriers", "shortie Jacks", or "Puddin' Dogs".

The original longer-legged forms were also preserved and, in England, were called "Parson Jack Russell Terriers". This form was recognised by the Kennel Club (UK) in 1990 and gained provisional recognition by the international breeds association, the F.C.I, in the same year. The name of the breed was changed to "Parson Russell Terrier" in 1999 by the Kennel Club (UK) and gained full recognition by the F.C.I under this name in 2001.

In the United States a group of enthusiasts opposed to the registration and regulation of the working breed registered "Parson Jack Russell" as a trademark. This led to the long-legged breed being recognised by the American Kennel Club under the name "Jack Russell Terrier". This name was changed to the "Parson Russell Terrier" in 2003 to conform with the nomenclature in other countries.

Breeders of the unregistered, working strain continued to use the Jack Russell name for their dogs. Currently there are few differences between the two types, although working Jack Russell Terriers are sometimes smaller than Parson Russell Terriers. However, it is likely that the differing approaches to breeding and the restricted gene pool of the registered type will result in divergence between the types, possibly leading to two very different breeds.

In England, the Kennel Club recently re-opened its registry to allow the inclusion of some Jack Russell Terriers under the Parson Russell name. The standard was extended to include slightly smaller dogs to about 10 inches (25 cm) high but still with the longer-legged form.

Individuals registered with the Jack Russell Terrier Club of Great Britain or the British Jack Russell Terrier Club and with registered parents and grandparents were accepted for registration. This may have a delaying effect on any divergence of the two types, but many breeders remain opposed to registration and are likely to continue to breed outside the Parson Russell standard and to continue to use the "Jack Russell Terrier" name.