The Cairn Terrier receives its name from the cracks where it would chase vermin. The Cairn Terrier represents the modern version of the original working dogs in Scotland. 
A short legged Terrier, strong build, well planted forward on its fore legs, with a foxy expression, hard coat and small pointy ears. The Cairn Terrier is not heavily built, but well muscled and in physical conditions for work. The head must be wide in proportion to the skull length, not too narrow, with a well defined stop. On the head the hair is slightly softer than the rest of the body. The muzzle is strong but never too long or heavy. The eyes, sunken and medium, not too large or prominent. The ears should not be too large or rounded at the tip; they should be well separated over the head and not too covered in hair. The body, with a wide thorax, a leveled, medium length back; the back should not be too short or too long and weak. The tail insertion is over the back level. The coat should be double, with abundant external hair, and a soft and dense undercoat, never open, hollow or too short: wavy trend is admitted, but never silky or curly hair. The Cairn admits every color except white (neither white patches); the ears, muzzle and tail should be darker. Height to the withers is approximately between 28 and 31 cm and the ideal weight between 6 and 7.5 kg, for the KC; for the FCI the male stands from 36 to 38 cm from the front part of the chest to the hindquarters.
WHO IS IT RIGHT FOR             
The Cairn Terrier is fantastic with children, but doesn’t tolerate too much touching – it will let the children know when the game must stop -. The Cairn Terrier is smarter than one could think. As a family dog, sometimes it chooses a special family member, although it is affectionate with everyone. The Cairn is not a lapdog; it is usually not lovey dovey, or clingy. It is an independent, smart and active dog, which can be decided and stubborn. Education should be soft and firm, and discipline requires only a few well chosen words. The owner should understand its Terrier manners: a land dog needs to dig; it loves to discover carrots growing in your garden, and its instinct make it a mouse hunter. In addition, the Cairn is territorial, especially males, and its territory includes you!
The Cairn Terrier is glad to please you. With patience and justice you can teach it how to do it. Some even accept the leash. Mr. and Mrs. Wallace.
The Cairn Terrier baby grows quickly during the first weeks.
The most important thing in an eight week Cairn Terrier is balance. The Cairn Terrier often goes through unleveled growth periods during the first year. In a breeder’s words, the dog “will probably go through a phase where it seems all ears, limbs and tail”. While it was well balanced at eight weeks, is should be so when reaching maturity, which is probably after a year. The Cairn Terrier continues gaining substance until after three Yeats. The tail should never be docked. The hind dewclaws should be removed as soon as possible; front dewclaws are optional. Males reach sexual maturity at early age.
Puppy hair “stripping” is begun when the puppy hair is loose. The coat should already be somewhat rough to the touch at three months. The coat usually darkens as adult hair grows out, and some cream or wheat colored specimens continues to darken on each shedding. The owner should supervise teething. It is known that some Cairn Terrier keep their baby teeth, and it can be necessary to remove them by a veterinarian. Excessive eating can be a problem, diet needs to be controlled, and limit snacks to twice or thrice a day. The adult dog usually maintains its weigh with 2/3 of feed per day is enough. It is normal for a young dog to bark; this habit should be stopped from the beginning.

Checkups for possible problems diminish health problems in puppies. 
The tail is never docked, it is left natural. Own. Susan W. de Witt.
Typically a resistant and long lived dog that enjoys life until 14 or 15, the Cairn Terrier requires a lot of outdoor activity. Hair care is not very demanding, although the external hard hair should be “stripped”. As in every breed, there are some hereditary anomalies that currently affect the breed, although less than normal in the Cairn Terrier. An unusual anomaly is reported which is known as craniomandibular osteopathy or lion jaw; it affects puppies and manifests with a sudden jaw swelling. It can be treated, maybe even corrected by itself, and it is rarely mortal. Krabble disease (globoid cell leukodystrophy) affects puppies with a few weeks or months – it is a blood anomaly that is mortal -. Another anomaly unusual in dogs (it is believed it is hereditary recessively) known as cerebral hypoplasia that has been reported in the Cairn and other Terrier breeds; it is quite rare and symptoms vary, it is sometimes progressive and it sometimes apparently corrects itself. In addition to hemophilia A and B, inguinal hernias, as well as progressive retinal atrophy, Von Willebrand and Legg-Perthes.
After eight weeks the Cairn Terrier puppy should have a balanced appearance; it will lose it during adolescence, but regain it as an adult.