Jack Russell Terrier
Breed at a glance
- Origin
- United Kingdom
- Weight
- 5–6 kg (11–13 lb) [ 1 ]
- Height
- ideal: 25–30 cm (10–12 in) [ 1 ] [ 2 ]
- Coat
- smooth, rough or broken
- Colour
- predominantly white, with patches of tan or black
intro
The Jack Russell Terrier is a British breed of small terrier . It is principally white-bodied and may have a smooth, rough, or broken coat, with markings of various colours. It derives from dogs bred and used for fox-hunting in North Devon in the early nineteenth century by a country parson , Jack Russell – for whom the breed is named – and has similar origins to the modern Fox Terrier . Though closely similar, it is a distinct and different breed from the Parson Russell Terrier . [ 3 ] Jack Russells are an energetic breed that rely on a high level of exercise and stimulation. It has gone through several changes over the years, corresponding to different use and breed standards set by kennel clubs. Recognition by kennel clubs for the Jack Russell breed has been opposed by the breed's parent societies – which resulted in the breeding and recognition of the Parson Russell terrier. Jack Russells have appeared many times in film, television, and print – with several historical dogs of note.
Health
Due to their use in hunting, in the US the Jack Russell is prone to contracting skunk toxic shock syndrome . [ 44 ] A 2022 study of life expectancy of dogs in the UK using veterinary data found the Jack Russell Terrier to have an average life expectancy of 12 years and 9 months, higher than any other breed in the study including crossbreeds. [ 45 ] A 2024 UK study found a life expectancy of 13.3 years compared to 12 years for crossbreeds and 12.7 years for purebreds overall. [ 46 ] A 2024 Italian study found a life expectancy of 8 years for the breed compared to 10 years overall. [ 47 ]
Description
Due to their working nature, Jack Russell terriers remain much as they were some 200 years ago. [ 28 ] They are sturdy, rugged, and tenacious, measuring 25–38 cm (10–15 in) at the withers , [ 29 ] and weighing 6–8 kg (14–18 lb) . [ citation needed ] The body length must be in proportion to the height, and the dog should present a compact, balanced image. Predominantly white in colouration (more than 51%) with black and/or brown and/or tan markings, [ 29 ] they exhibit either a smooth, rough or a combination of both which is known as a broken coat. A broken-coated dog may have longer hair on the tail or face than that which is seen on a smooth-coated dog. [ 30 ] The head should be of moderate width at the ears, narrowing to the eyes, and slightly flat between the ears. There should be a defined but not overpronounced stop at the end of the muzzle where it meets the head, and a black nose. The jaw should be powerful and well boned with a scissor bite and straight teeth. The eyes are almond shaped and dark coloured and should be full of life and intelligence. Small V-shaped ears of moderate thickness are carried forward on the head. [ citation needed ] When the dog is alert, the tip of the V should not extend past the outer corner of the eyes. The tail is set high and, in the past, was docked to approximately 10 cm (5 in) to provide a sufficient handhold for gripping the terrier. [ citation needed ] The Jack Russell should always appear balanced and alert. [ 29 ] The red fox is the traditional quarry of the Jack Russell terrier, so the working Jack Russell must be small enough to pursue it. Red foxes vary in size, but across the world, they average from 6–8 kg (13–17 lb) in weight and have an average chest size of 30–36 cm (12–14 in) at the widest part. [ 31 ]
Haematology
Severe combined immunodeficiency (SCID) is a genetic disorder that is related to a defective antibody response. An autosomal recessive form of SCID has been reported in the Jack Russell Terrier. The condition usually results in death from an infection during the first few months. The allele responsible for the condition is found in less than 1.1% of Jack Russell Terriers and a DNA test exists for the condition. [ 52 ]
Temperament
Jack Russells are a working terrier . [ 41 ] Originally bred to bolt foxes from their dens during hunts, they are used on ground-dwelling quarry such as groundhog, badger, otter, and red and grey fox. [ 42 ] To accomplish this, the dog will not bark but will expect attention to the quarry continuously. Because the preservation of this working ability is important to most registered JRTCA/JRTCGB breeders, Jack Russells tend to be extremely intelligent, athletic, fearless, and vocal dogs. [ 13 ] Their high energy and drive make these dogs ideally suited to a number of different dog sports such as flyball or agility . [ 43 ] Obedience classes are also recommended to potential owners, [ 42 ] as Jack Russells can be stubborn at times and aggressive towards other animals and humans if not properly socialized. [ 13 ]
Neurological
An inherited form of ataxia has been recognised within the Jack Russell Terrier for more than 50 years. Myokymia and seizures are often seen alongside the condition. A 2014 study identified the KCNJ10 gene as being responsible for the spinocerebellar ataxia accompanied by myokymia and/or seizures in the breed. This condition also affects the closely related Parson Russell Terrier and Russell Terrier . [ 55 ] A UK study found the Jack Russell Terrier to be predisposed to steroid-responsive meningitis-arteritis . The breed was 6.91 times more likely to contract the disease than other breeds. [ 56 ]
Eye disorders
Primary lens luxation is an inherited condition that often occurs in Jack Russell Terriers as well as other breeds. [ 50 ] A study identified a mutation in the ADAMTS17 gene as being responsible for the condition. [ 51 ]
Dermatological
Black hair follicular dysplasia is a rare type of follicular dysplasia where only the black hairs of a bicolour or tricolour dog will be affected. Jack Russell Terriers are known to be a breed that may acquire the condition although it is seen in several breeds and in mongrels . [ 48 ] A type of ichthyosis that can be distinguished both clinically and histopathologically has been identified in separate Jack Russell Terrier families. This ichthyosis is also more severe than other forms. A mutation in the TGM1 gene has been found to be the cause. [ 49 ]