The Jack Russell Terrier belongs to the third group in this classification: the Terriers. The dogs in this group are mainly small dogs. They have a good jaw, which gives them, together with their strong, powerful physique and their liveliness, the ability to kill. Indeed, Terriers were mainly used to hunt burrowing animals. Whatever the breed, these are dogs which therefore also have a fairly present (fighting) character. The Jack Russell Terrier belongs more precisely to the first category of this group, that which concerns large and medium-sized Terriers.

The Jack Russell Terrier owes its name to the pastor Jack Russell who, in the 19th century, developed this breed in the county of Devon (England) from ancient wire-haired Terriers in order to obtain a dog capable of forcing the fox, the rabbit and wild boar underground. The Jack Russell created a strain of Fox Terriers specifically designed for hunting. These dogs had the mission of following the game into its burrow and dislodging it. Two varieties therefore developed from this standard to give two fairly similar breeds. The Jack-Russell Terrier quickly became very popular in his country and was recognized by the Kennel Club and the F.C.I. in 1990. It was around the 1980s that it appeared in France.

The Jack Russell Terrier is one of the small breeds. The male measures approximately 35 cm and the female 33 cm. Its weight does not exceed 7 kg. This is a dog built for speed and endurance. It is longer than tall with thick, loose skin. Its gait is clear and lively. The body of the Jack Russell Terrier is quite long. His neck is muscular, his chest moderately descended. His back is strong and straight and his back is slightly arched. He has strong, muscular limbs. Its feet have tight toes. Its tail is set high, it is also strong and straight. His skull is flat. Its jaws are powerful. Its almond-shaped eyes are dark in color. Its ears are small, V-shaped, falling forward and carried against the head. The coat of the Jack Russell Terrier is described in its standard as being entirely white or white with tan, lemon or black markings. These marks should preferably be limited to the head or the base of the tail. Its coat is rough, dense and tight whether it is smooth or hard.

The Jack Russell Terrier has a fairly long life expectancy compared to other breeds. Indeed, in the absence of diseases of course, it can live a good fifteen years, some individuals even reaching twenty years. The most common diseases in this breed are: luxation of the lens and cataracts, deafness , luxation of the patella and ataxia.Luxation of the lens and cataract are two congenital and correlated diseases in the Jack Russell Terrier. Around 3 to 6 years of age, lens dislocation can occur. The first symptoms are: reddening of the eye, clouding of the lens and trembling of the iris. Without surgical intervention, this disease can lead to the development of glaucoma or even blindness. A genetic test makes it possible to detect individuals carrying this mutation. Cataract, for its part, also consists of a partial or total opacification of the lens causing partial or total loss of vision. Deafness in the Jack Russell Terrier may be less common than initially thought. However, it would be linked to the white color of the coat and therefore to pigmentation genes. Consequently, deafness can be inherited from parents, hence the need to test breeding individuals. Dislocation of the patella is a hereditary condition or occurs following trauma. It can cause damage to the bones, ligaments and cartilage of the joint. Ataxia is a manifestation of degeneration of the cerebellar cortex and areas of the brain. The first symptoms are a lack of coordination of the animal's voluntary movements. This can also manifest itself as balance disorders, falls, movement dysmetry, difficulty gripping food, etc. An MRI makes it possible to make the diagnosis of this disease for which there is unfortunately no treatment, euthanasia often taking place after the first symptoms appear. The Jack Russell Terrier is also predisposed to myasthenia gravis, Legg-Perthes disease. Calvé and Von Willebrand disease. His coat requires very little maintenance.

Despite being rather short on legs, the Jack Russell Terrier is robust, active and agile. He is a dog with a lot of personality, a strong, stubborn and dominant character, which he does not hesitate to assert. But he is also a cheerful, playful dog (capable of playing for hours without getting tired), devoted and very affectionate. He still remains a hunter at heart with a temperament, if not sometimes biting, in any case a fighter. He’s a little dog with a big character! He also tends to follow the slightest trail, which requires outings on a leash to avoid running away. If he can adapt to life in an apartment, he will nevertheless need to be able to satisfy his great need for exercise on a daily basis. The Jack Russell Terrier must be socialized perfectly and early. Well structured thanks to a firm and rigorous education, he learns quickly. It will also be necessary to teach him the prohibitions and clearly indicate his place in the family hierarchy.