Jack Chi

Linda Simon
Dr Linda Simon (MVB MRCVS, University College Dublin)
Photo of adult Jack Chi
GB / Flickr.com

Cute and compact, the Jack Chi is a fabulous mix of two very popular purebreds; the feisty Jack Russell Terrier and the confident Chihuahua. Most will be loyal, affectionate and quite energetic. While small, these dogs have big personalities and, whether you like it or not, will quickly become the centre of your world!

Jack Chis are less dainty and fragile than their Chihuahua parent but not quite as stocky as the Jack Russell. They are built in good proportion with well-muscled limbs, ensuring a bouncy and athletic gait. Most will have short and thick coats, which come in a variety of attractive colours and shades.

About & History

Also known as the Jackhuahua, the Jack Chi combines two well-loved and in demand pedigrees; the Chihuahua and the Jack Russell Terrier. The Jack Chi was developed within the States sometime in the late 20th century secondary to the increased consumer demand for designer dogs. As is true for most of the hybrids created around this time, their exact date and location of origin is unknown.

The Jack Russell Terrier

The Jack Russell Terrier is an English breed of dog that is known for its spunky personality and bravery. They make great family pets but have a reputation for being a bit of a handful at times. They were originally bred from Fox Terriers for the purpose of fox hunting around 200 years ago.

Through the years, they have also been used as very successful rat hunters, ensuring their prey drive remains high even today. Their name comes from the man credited with their development, Reverend John Russell. Jack Russells are very closely related to the Parson Russell Terrier, who has longer limbs. While mainly kept as pets today, their sporting ability makes them great competitors and they are regulars on the Flyball and agility circuits.

The Chihuahua

Chihuahuas are the smallest dog breed in existence, with a female called Milly currently holding the World Record at a teensy 9.65cm. Owners admire them for their faithfulness and loving natures. The first Chihuahuas are thought to have originated within Mexico, perhaps from the ‘Techichi’, an ancient breed of dog that lived during the Toltec Empire.

Though South American, the Chihuahua breed was actually refined across the border in Texas where they were further refined to create the animal we know and love today. Never used as working dogs, Chihuahuas are much-loved lap dogs. A host of celebrities, including Paris Hilton and Britney Spears have owned the breed, ensuring their popularity remains high.


Jack Chi Large Photo
GB / Flickr.com

The Jack Chi looks somewhat more like their Jack Russell than their Chihuahua parent though they will be smaller with a more rounded skull. They have a medium-sized muzzle and dark brown, circular eyes. Their ears may stand erect or flop forwards but are always classically triangular in shape. Their limbs are relatively short but straight and they should have lean, rather wiry bodies. They have good abdominal tuck-up and a tail that curls gaily above their back.

Weighing anything from 3.5kg to 8kg and measuring from 30cm to 38cm, these dogs do vary in size quite a bit. They are a small-breed, but never as small as the diminutive Chihuahua.

The fur of the Jack Chi is usually short and neat but can be slightly longer in some. They have a dense coat and can shed quite a lot, especially in the warmer seasons. Brown and white and tan and white are the two most common coat colour combinations but dogs can be a number of additional colours, including black, fawn and cream. Most will have large spots and patches.

Character & Temperament

The real charm of the Jack Chi is their outgoing personality. They are confident (almost without exception) and rarely shy even in new surroundings. They can have a tendency to want to be dominant, particularly if homed with a more sensitive breed of dog, who they may walk all over. They enjoy company of any type (two or four-legged!) and can learn to co-exist with children of all ages and most other dogs, just as long as they are introduced to them from a young age and socialized sensibly.

The prey drive of the Jack Chi is variable but some individuals can find it impossible to ignore the alluring scent of a bird or squirrel when out and about. They will often chase and bark after them and may not necessarily respond to you when you call them back. This can mean that a long lead is preferable to going off lead when in public areas.

While generally a well-balanced dog, the Jack Chi is not always the easiest to get along with. Some are prone to developing destructive behaviours and this is especially true in those that are left alone for too long and/or are under-exercised. Similarly, separation anxiety can become a problem in some.


Quick to learn, eager to participate in training sessions and with enthusiasm to spare, the Jack Chi gets an A+ for potential. Despite this, these dogs can be tricky to train as they are notoriously stubborn and can display hyperactivity. They can become distracted and need lots and lots of positive reinforcement to maintain their interest.

Owners should not assume that the Jack Chi will simply ‘settle into a routine over time’ as this is often not the case and without firm training they can be difficult to live with. They need consistent training and clear-cut rules that are followed by all family members.


As there are well-documented health conditions that can affect both parent breeds, breeders should use the appropriate breeding schemes (as they would when breeding pedigrees) to avoid a high incidence of any particular genetic disease within the Jack Chi population.

Patellar Luxation

Many small dogs are prone to a condition known as patellar luxation, whereby the kneecap pops out of the correct position. This can cause some dogs a great deal of pain and distress, while others seem completely unaffected by it. A vet exam can usually diagnose the condition and X-rays are generally advised. For some, a surgical procedure to correct the defect is the best way forward.

Mitral Valve Disease (MVD)

MVD is a condition affecting the mitral valve (the valve that separates the left atrium and ventricle within the heart) causing improper blood flow and an audible heart murmur. Initially, dogs may not show any signs of being affected but over time they can develop a cough and struggle to keep up with their regular exercise. Medication is available to manage this condition, though there is no cure.

Tracheal Collapse

Dogs with tracheal collapse tend to experience symptoms that worsen with time. The windpipe is flattened due to weakened cartilage, restricting airflow and resulting in a chronic, dry cough. As the symptoms are not specific, tests, such as chest X-rays, will need to be undertaken to confirm the diagnosis.

Medication can help to relieve the coughing and any dog with a collapsed trachea should be maintained at a lean body condition and should not be walked using a neck collar. For some, a specialised surgery will offer the best prognosis.

Periodontal Disease

Those with smaller mouths are more prone to periodontal disease as they can have overcrowding of their teeth. It is also often the case that smaller dogs are ‘fussier’ eaters and are typically given a soft, wet diet, which can lead to calculus build-up.

Periodontal disease can be prevented by regular tooth brushing and the use of products that break down plaque (such as powders and gels). Many dogs will benefit from a veterinary dental cleaning or two (or three!) during their lives, to keep on top of things.

Exercise and Activity Levels

Active little critters, Jack Chis have bundles of energy and it should not be assumed that because they’re small they do not need long walks. As well as a couple of nice, varied hikes each day, they should be included in lots of fun games. They enjoy using their nose in scent games and relish the opportunity to use their brain and solve food puzzle toys.


For most, grooming consists of being brushed once or twice a week. They should have their ears checked and cleaned as needed and, in an ideal world, would have their teeth brushed at least every other day.

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