Breed Standard
The basis of breed shows is the judging of dogs against the 'Breed Standard', which is the prescribed blueprint of the particular breed of dog. For all licensed breed shows, The Kennel Club Breed Standards must be used for the judging of dogs.
The Breed Standards are owned by The Kennel Club, and all changes are subject to approval by The Kennel Club General Committee. New Breed Standards, for newly recognised breeds, are drawn up once the breed has become sufficiently established within the UK. Careful research is conducted into the historical background, health and temperament of any new breed before Kennel Club recognition is granted. The Kennel Club currently recognises 196 breeds.
For Chihuahuas, the standards for the two breeds are identical except for the description of the coat. In December 2007 they were amended to specifically exclude merle coloration. They were further amended in October 2009 following discussions with The Kennel Club to address possible breed health concerns.
https://www.the-british-chihuahua-club.org.uk/AboutUs/BreedStandard.php
Smoothcoat Breed Standard
General Appearance
Small, dainty, compact.
Characteristics
Alert little dog; swift-moving with brisk, forceful action and saucy expression.
Temperament
Gay, spirited and intelligent, neither snappy nor withdrawn.
Head and Skull
Well rounded 'apple dome' skull, cheeks and jaws lean, muzzle moderately short, slightly pointed. Definite stop.
Eyes
Large, round, but not protruding; set well apart; centre of eye is on a plane with lowest point of ear and base of stop; dark or ruby. Light eyes in light colours permissible.
Ears
Large, flaring, set on at an angle of approximately 45 degrees; giving breadth between ears. Tipped or broken down highly undesirable.
Mouth
Jaws strong, with a perfect, regular and complete scissor bite, i.e. upper teeth closely overlapping lower teeth and set square to the jaws.
Neck
Slightly arched, medium length.
Forequarters
Shoulders well laid; lean, sloping into slightly broadening support above straight forelegs, set well under chest giving freedom of movement without looseness.
Body
Level back. Body, from point of shoulder to rear point of croup, slightly longer than height at withers. Well sprung ribs, deep brisket.
Hindquarters
Muscular; hocks well let down, with good turn of stifle, well apart, turning neither in nor out.
Feet
Small and dainty, turning neither in nor out; toes well divided but not spread, pads cushioned, fine, strong, flexible pasterns. Neither hare- nor cat-like, nails moderately short.
Tail
Medium length, set high, carried up and over back (sickle tail). When moving never tucked under or curled below the topline. Furry, flattish in appearance, broadening slightly in centre and tapering to point.
Gait/Movement
Brisk, forceful action, neither high-stepping nor hackney; good reach without slackness in forequarters, good drive in hindquarters. Viewed from front and behind legs should move neither too close nor too wide, with no turning in or out of feet or pasterns. Topline should remain firm and level when moving.
Coat
Long Coat:
soft texture (never coarse or harsh to touch) either flat or slightly wavy. Never tight and curly. Feathering on ears, feet and legs, pants on hindquarters, large ruff on neck desirable. Tail long and full as a plume.
Smooth Coat:
smooth, of soft texture, close and glossy, with undercoat and ruff permissible.
Colour
Any colour or mixture of colours but never Merle (dapple).
Size
Weight: up to 2.7kg (6lb), with 1.8 - 2.7kg (4 - 6lb) preferred.
Faults
Any departure from the foregoing points should be considered a fault and the seriousness with which the fault should be regarded should be in exact proportion to its degree and its effect upon the health and welfare of the dog.
Note
Male animals should have two apparently normal testicles fully descended into the scrotum.
https://www.the-british-chihuahua-club.org.uk/AboutUs/BreedStandardSC.php
Long Coat Breed Standard
General Appearance
Small, dainty, compact.
Characteristics
Alert little dog; swift-moving with brisk, forceful action and saucy expression.
Temperament
Gay, spirited and intelligent, neither snappy nor withdrawn.
Head and Skull
Well rounded 'apple dome' skull, cheeks and jaws lean, muzzle moderately short, slightly pointed. Definite stop.
Eyes
Large, round, but not protruding; set well apart; centre of eye is on a plane with lowest point of ear and base of stop; dark or ruby. Light eyes in light colours permissible.
Ears
Large, flaring, set on at an angle of approximately 45 degrees; giving breadth between ears. Tipped or broken down highly undesirable.
Mouth
Jaws strong, with a perfect, regular and complete scissor bite, i.e. upper teeth closely overlapping lower teeth and set square to the jaws.
Neck
Slightly arched, medium length.
Forequarters
Shoulders well laid; lean, sloping into slightly broadening support above straight forelegs, set well under chest giving freedom of movement without looseness.
Body
Level back. Body, from point of shoulder to rear point of croup, slightly longer than height at withers. Well sprung ribs, deep brisket.
Hindquarters
Muscular; hocks well let down, with good turn of stifle, well apart, turning neither in nor out.
Feet
Small and dainty, turning neither in nor out; toes well divided but not spread, pads cushioned, fine, strong, flexible pasterns. Neither hare- nor cat-like, nails moderately short.
Tail
Medium length, set high, carried up and over back (sickle tail). When moving never tucked under or curled below the topline. Furry, flattish in appearance, broadening slightly in centre and tapering to point.
Gait/Movement
Brisk, forceful action, neither high-stepping nor hackney; good reach without slackness in forequarters, good drive in hindquarters. Viewed from front and behind legs should move neither too close nor too wide, with no turning in or out of feet or pasterns. Topline should remain firm and level when moving.
Coat
Long Coat: soft texture (never coarse or harsh to touch) either flat or slightly wavy. Never tight and curly. Feathering on ears, feet and legs, pants on hindquarters, large ruff on neck desirable. Tail long and full as a plume.
Smooth Coat: smooth, of soft texture, close and glossy, with undercoat and ruff permissible.
Colour
Any colour or mixture of colours but never Merle (dapple).
Size
Weight: up to 2.7kg (6lb), with 1.8 - 2.7kg (4 - 6lb) preferred.
Faults
Any departure from the foregoing points should be considered a fault and the seriousness with which the fault should be regarded should be in exact proportion to its degree and its effect upon the health and welfare of the dog.
Note
Male animals should have two apparently normal testicles fully descended into the scrotum.
https://www.the-british-chihuahua-club.org.uk/AboutUs/BreedStandardLC.php
A Closer Look at the Chihuahua
by Laurence Fitt-Savage
Reproduced from the British Chihuahua Club Handbook 1987
https://www.the-british-chihuahua-club.org.uk/AboutUs/CloseLook.php
A Closer Look at the Chihuahua
by Laurence Fitt-Savage
Reproduced from the British Chihuahua Club Handbook 1987
SKULL
The most individual attribute of any breed tends to be the head; the Chihuahua is no exception. As a toy/lap/pet dog this individuality is a key function of the breed.
The skull of the Chihuahua is of most unusual shape. The skull of 'basic dog' is like an elongated cube, with a bony occipital peak and a slight bony ridge along the centre line of the skull, where the plates of the cranium knit together. The Chihuahua, as a legacy of the dwarfing of the breed, has a large rounded baby-like skull. Mammalian babies tend to be born with disproportionately large heads (and eyes) which grow on more slowly than the rest of the animal. In the chi this largeness of head and eye is never completely lost. The large head of a whelp requires that the many bones which knit together to form the skull must be capable of movement at birth to allow the bitch to pass the head. In chis these bones do not always grow together as the head develops and changes shape during puppyhood. A small gap (molera) is left atop the skull where the bones fail to meet. Provided this gap is not large, and that there are not several gaps, the presence of a molera is of little significance. In many Chihuahuas the cranial plates do knit together, they should not however form a crest or ridge where they meet.
In shape the skull should resemble an apple (a cooking apple is generally thought most descriptive), it should not be a perfect round (ball) shape. A round skull would lose breadth between the ears, and less room within the cranium. The eye sockets should be well protected with a bony surround, it is this protection of the eye sockets which lifts the front lobes of the skull and creates greater width at eye level. This protection also forms the basis for the required distinct stop. A round skull lacking this protection will either have small eyes, or 'frog' eyes which stick out.
Jaws and Cheeks
Jaws and cheeks are supposed to be lean, muzzle 'moderately short, slightly pointed' and the stop 'definite'. Coarse dogs have too broad a muzzle and broad cheeks, there is not enough distinction between muzzle and skull. Snipy dogs have cheeks pinched in beneath the eyes, and narrow muzzles; their jaw muscles are of poor substance.
Muzzle
The muzzle itself is fairly short; the Chihuahua is a member of the bracycephalic group (large heads and short muzzles). Ultra short muzzles are not desirable, they can lead to respiratory problems. Long muzzles are untypical - they spoil the balance of the head, lead to 'foxy' faces with insufficient cheek and stop, often allied to flattened, plain heads. The muzzle is slightly pointed - flattened muzzles tend to be coarse, or too short (even perhaps with a turned up nose). The flat muzzle often accompanies an undershot mouth, if too pointed it may indicate an overshot mouth. A 'definite' stop does not mean the skull is at right angles (90°) to the muzzle. Given that the muzzle is the horizontal (sloping neither up nor down), then the skull should describe an angle of approx. 100°. A very short muzzle may appear to be set in the skull, describing an angle less than 90°; a legacy of the flat-faced breeds introduced into chi ancestry to shorten the muzzle (Pugs, Pekes. etc.). It is potentially a source of breathing problems.
Bite
A correct scissor bite is such that, side view, the top incisors just overlap, in front of the bottom ones, but the bottom canine fits neatly in front of the top one. if the incisors meet edge to edge, this is a 'level' mouth, not scissor. 'Set square to the jaws', it must be noted, means that the teeth are set at approx. 90° to the gums. It does NOT mean that the incisors should be lined up neatly in a straight line like guardsmen; the dental arch (arcade) should curve gently forward from the canines.
Given that the head and muzzle are the result of dwarfing, it is not too surprising that the upper and lower mandibles are not evenly shortened; the result is an over- or under-shot bite. If overshot, the upper incisors protrude beyond the lower, in severe cases the bottom incisors may be level with the top canines. If undershot, the bottom incisors stick out beyond the top ones.
Ideally the incisors should be even in size, strong and white, with six top and bottom. In shorter muzzles this is sometimes difficult to achieve - there may be insufficient room, so the dog may have only 4 bottom incisors (acceptable in U.K. if the teeth are of even size with no large gaps); the teeth may be uneven in size, or the bottom incisors may be set in a straight line. How serious these mouth faults are is a difficult point. Unless severe, a poor bite will probably have no significant effect on the dog, but successive generations may show deteriorating mouths. Uneven teeth, or the odd gap are considered by some to be unavoidable in the best heads, although there is no reason why the best of heads should not carry a perfect mouth.
Eyes
Although large, a Chihuahua's eyes should not protrude, as this would increase the risk of injury. Bulging, frog eyes are not attractive, and are particularly prone to weeping and damage. Weeping of the eyes is quite a common problem in Chihuahuas, the most serious cause is ingrowing lashes, but draughts, dust and the moulting of the fine short hair around the eyes are also causes. When injured the eyeball often turns cloudy blue, either in whole or just around the injury. This should not be confused with the staring, light blue 'wall eyes' (common in merle collies) which look uncanny and unattractive, and are not the light eyes permitted by the standard. The ruby eye is associated with pale pigmentation of the nose, in light coloured Chihuahuas, and reflects a most attractive colour in the dark.
Chihuahuas' ears are set on the side of the head rather than the top, and are carried erect, flaring out at an angle, often wrongly described as being at 'ten to two'. Particularly alert, or dozy, chis will naturally use their ears, pricking them higher, or laying them flat to the skull, but in repose should revert to the 45° angle. The ears are large, with rounded ends to the pointed tips, not to be confused with the rounded ends of the 'bat ears' of such as the French Bulldog. Because they are so large, Chihuahuas' ears sometimes take a while to become fully erect, the ears of teething pups are often soft at the tips, bending forward or back. Truly soft ears, those which fail to stand up, flop down beside the head and are both a serious fault in the show ring and a more likely victim of problems such as canker. Small, kitten ears set high on the head produce an alien, foxy, pommy expression and are sometimes difficult to weed out of breeding lines.
The neck is 'slightly arched, medium length' for strength, as it both carries the weight of the head and is part of the forequarters assembly. If the neck is too long, the whole dog will probably be built along racy, whippet-like lines with long spindly legs. Extension of the vertebrae of the neck generally accompanies a pro-rata extension of the rest of the spinal column, giving long, weak backs, slab sides and long, ratty tails. This so-called 'deer-type' is no longer as common in Chihuahuas. More common is the Chi with a stuffy neck - too short a neck leaves too little room for the muscles, and is associated with heavy, overbuilt forequarters. The head, in such a chi, often looks as if it has been stuck straight on to the body, especially in longcoats where the ruff hides the true lines of the neck.
When felt the neck, measured from base of skull to the shoulder, should be approx. one-third of the length of the back. The arch of the neck is required for strength, to be effective it must carry the head forward, and not up (star-gazing). If the arch of the neck is inverted the dog's movement suffers, being less smooth and rhythmic, choppy and without reach and drive.
lt should be noted in passing that a Chihuahua should have no loose folds or flaps of skin on the neck, the chi should offer clean bodylines to the eye.
Forequarters
The forequarters (or forehand) of the dog may not always receive as much attention as the hindquarters, but they are equally important. The hindquarters provide the drive, the forequarters propel on the turn, absorb the impact of each stride or jump, ensure travel in a straight line, assist in maintaining the stability of the centre of gravity and carry weight. Faults in the forequarters assembly can therefore have serious consequences. Note that the foreleg does not end at the elbow, although its structure is harder to see than that of the hindquarters.
The shoulder, as the foundation upon which the forequarters are based, should be correctly laid, the most efficient arrangement is generally accepted to be 45° from the horizontal (side view). An upright shoulder (an angle significantly greater than 45°) tends to shorten the shoulder blade, thereby also shortening the muscles anchored to it, reducing their efficiency. There is also a loss of reach, as the foreleg cannot straighten beyond the angle of the shoulder, and this reduces drive and is the root of a number of serious gaiting faults.
The shoulders are also required to be 'lean, sloping into slightly broadening support'. This refers to the view from the front of the dog. The shoulders lay along the ribs; too much muscle on the shoulder pushes the tops of the shoulder blades apart. These 'loaded shoulders' are heavy, rather than lean, and result in a lack of balance. The shoulder point is tied in closer to the ribcage and the elbow is forced out of line, which is an ugly fault. A dog with loaded shoulders may also appear overbuilt at the front, tailing off to weaker hindquarters.
If the hindquarters are better angulated than the front and provide more drive than the front can accommodate, problems occur. Unless a corrective remedy is found the dog 'pounds' - the front legs hit the ground before the hindlegs have completed their forward push, the resultant excessive strain may cause the dog to 'break down' in front, especially at the pasterns. Excessive rising and falling at the withers often betray this condition. To avoid pounding, the dog may flick up its front pads just prior to impact. This reduces the shock of impact, the dog lands on the heel pads, which act as buffers. 'Padding' as this fault is known, often looks most smart to the casual observer, but it is only the dog's natural compensation for its structural deficiencies, and a trap for the unwary!
An alternative method of avoiding contact is to throw the front legs high in the air, the 'Hackney' gait. This is specifically described in the standard as a fault, in part because, for just a few specific toy breeds this is, for differing reasons, the required gait.
Balance is determined in two situations; on the move (kinetic balance) and standing still (static balance).
Static balance is achieved if the dog's structure allows standing on all fours with the minimum of effort. For this to be possible the base of its support (the heel pad) must be vertically beneath the centre of gravity of the shoulder, although the support is not a solid vertical 'pole'. 'Forelegs set well under' means that the humerus must be long enough to set the legs under the shoulder, the best arrangement being the humerus set at 90° to the shoulder blade, and of the same length. The ultra straight 'terrier front' is the result of a shortening of the humerus with a resultant shorter, more upright shoulder. This may look extremely smart, but it is most definitely incorrect in a Chihuahua. The foot is set too far forward, rather than being well under. The leg appears to be a continuation of the neck, with no brisket visible in front of it. (A) The straightness throws the foot forward of the centre of gravity and straightens the pasterns until they tend to knuckle over. This is NOT the straight front the standard refers to. A short humerus would bring the elbow above the brisket line. To give freedom of movement the elbow is lower. This of course, is freedom of movement front to back, 'looseness' refers to side to side movement and is not wanted.
To get the heel pad beneath the centre of the shoulder requires a slight bend at the pastern joint. If the pasterns are too upright, weight will be thrown forward onto the toes, risking damage to the foot. The standard's 'straight forelegs' refers to the legs as seen from the front. If completely straight (side view) from elbow to heel, the leg muscles are constantly at work equalising the pull forwards and back, so that the leg tends to quiver. If the muscles are weak the pastern will knuckle over. If the pastern bends forward too much there is constant strain on the muscles of foot and leg, and displace certain small bones in the foot.
Viewed from the front the foreleg should be straight from point of shoulder to the pad. However to be in complete balance the foot may incline inwards slightly from the vertical, to ensure that the foot is vertically beneath the centre of gravity of the shoulder blade.
Once on the move, kinetic balance requires maximum work for minimum effort, to increase stamina and reduce fatigue. Viewed from the side the radius and ulna should be parallel with a line drawn from foot to centre of the shoulder, when the foot is in contact with the ground.
From the front the foreleg should still be straight, but it must be noted that the faster a dog moves, the greater the tendency to place the feet near the centre line beneath the body. This is not a fault, it helps prevent body roll, which would be unduly tiring. However, the speed a chihuahua is normally gaited at in the ring should not require anything approaching single-tracking. The opposite of single-tracking, 'paddling' can also be a problem. Tied in elbows are restricted in their movement, as a result the legs are thrown wide of the body, which rocks from side to side because the feet fall so wide apart.
Other gaiting faults combine various features of a front that is not straight, the leg bending at elbow, pastern or even just the foot. Movement is most efficient when the leg, from point of shoulder to foot, is a straight column of bones. Loose elbows which 'flap in the wind' wide of the body throw the leg inwards. Weak pastern joints throw the pastern out, or turn the feet both in and out. 'Weaving' is the result of the elbow problem, 'winging' that of the pasterns.
Musculature
Each forelimb is an entirely separate structure, only anchored to the main frame of the dog's skeletal structure by muscle and ligaments. Therefore weak musculature will compound the problems of poor bone structure, or it may force sound structure into unnatural situations. Faults of both bone and muscle must therefore both be considered important. Equally problems evidenced in puppyhood may resolve as the adult dogs develop and harden the necessary muscle, roadwork is often the prescribed remedy for loose elbows in a young dog. Age is not always a benefit however. Continued muscle development on upright shoulders often results in the fully mature dog, at 2 to 3 years old, becoming overbuilt in front, characteristically 'stuffy' in neck.
The hindquarters, from the croup to the feet, are more involved in the provision of drive than in the maintenance of stability. Thus the dictates of stable balance are modified to cope with the not entirely compatible requirements for providing drive. The hip joint is therefore a more straightforward ball and socket joint, with the hip securely anchored to the spine, creating fewer mechanical constraints in the delivery of push. It should also be noted that the hock is a joint, not to be confused with the hind pastern.
Static balance is achieved when, viewed from the rear, the hind feet are equally spaced either side of the centre of gravity (an imaginary vertical line drawn through the centre of the pelvis, usually the root of the tail). For perfect balance the leg should form a straight, vertical column of bones from pad to hip joint. A modified balance is achieved by spreading the hind legs apart and back slightly, usually to display alertness or aggression, or to lower the croup and straighten the topline. Free-standing Chihuahuas should not show more than a minor amount of stretch, and never stand artificially stretched like a gundog.
Balance, modified or not, will be lost if the hind legs are not straight, i.e. if the hocks are turned in or out. Turned out hocks are the less common, they turn the feet in, 'Pigeon-toed'. Turned-in hocks, 'Cowhocks', are a well known and more prevalent fault. Lack of room forces the stifle out, which in turn forces in the hocks and splays out the feet. In cows this allows room for the udder but in dogs it is a fault as it seriously weakens drive. Drive is provided at an angle to the desired line of movement.
When the dog moves away these faults and more may be revealed. Hocks 'well apart' refers to the fault of moving close (brushing hocks). This fault has to be distinguished from single-tracking, which is the natural tendency of most breeds as their speed increases. The reason and extent of this tendency are the same, front and back. When a dog is 'moving close' behind, the hind pasterns brush past each other and may even touch. The stifles usually break the hip-foot line as well. Drive is lost as a result. The condition is often attributable to weak rearing muscles.
The differing requirements for hindquarters mean that the pelvis is thought most efficient at 30° to the horizontal (not the 45° of the shoulder). If the pelvis (& thus croup) is steeper, forward reach is gained, but push and follow through are restricted. If the pelvis is flat, forward reach is reduced, but the length of muscle from pelvis to hock shows an apparent increase. This however is not so as the femur, which tends to lie at 90° to the pelvis, is nearer the vertical, straightening the stifle joint and decreasing that joint's ability to operate as a pulley for the rearing muscles and ligaments. A shallow croup gives hind movement that is stilted, in Spitz breed style, whilst a steep croup shows up as slack hind movement and a 'Goose-rump'
Angulation of the hindquarters (good turn of stifle) is required for extra speed. Increasing the turn of stifle proportionately increases the length of both the thigh and second thigh, thereby also lengthening the rearing muscles. These muscles, particularly of the second thigh, provide the drive. Weak hind muscles lead to poor hind action, hence 'Muscular' in the standard.
The natural result of lengthening the second thigh, by developing a good turn of stifle, is that the hind pastern shortens, giving hocks that are 'well let down' - i.e. close to the ground. A shorter hind pastern gives greater endurance. Ideally the hind pastern should incline slightly forward - foot slightly behind the hock, bur a vertical hock is the norm in the showing. The hind pastern should not incline backwards, foot in front of the hock, since these 'sickle hocks' imply that the Achilles tendon is unable to fully extend the leg. In more severe cases the dog may look as though it bounces up and down on its hind feet. Rather than being directly under the pelvis, the hind foot should stand so that the hind pastern is beneath the point of buttock.
The stifle joint is most unusual in construction. The patella runs between grooves on the end of the femur, to prevent overstraightening and act as a pulley for the rearing muscles. If the muscles and ligaments are slack the patella may jump the groove. In a dwarfed breed like the chihuahua it is more likely that the groove may not develop in proportion to the joint, shallow grooves therefore tend to be more common. This fragile joint is particularly susceptible to external damage. Enthusiastic pulling and tweaking of the hind leg can have serious results. The judge may find this patella luxation (slipping stifle) evidenced by hopping, locking the leg straight when standing, or by feeling (and sometimes hearing) the patella move when gently handled. The problem is another that age tends to amplify, and the unnatural wear on the joint may lead to arthritis.
Hip dysplasia also regularly leads to arthritis, and is not confined to big dogs, it is known in chihuahuas. HD can be debilitating in its severest form. HD occurs where the ball joint of the femur does not fit snugly in the socket of the pelvis. The result is uneven wear on both surfaces, and strain on the muscles. Subclinical HD (showing no external symptoms) is tested for by X-Rays in the most susceptible breeds, which tend to be the larger and heavier ones. Like all other structural faults HD must usually be assumed to be hereditary and breeding programmes planned accordingly to discard, rather than store up problems for future generations.
Back
Good conformation does not begin and end with the structure of the limbs, nor does soundness relate only to movement. The spinal column, from neck to tail, has an important role to fulfill. The vertebrae are more than just protection for the spinal cord. They anchor the limb muscles which allow movement, they are the foundation of the dog's skeleton. Differing stresses along the length of the spine mean that this strength must be combined with a degree of flexibility, the spine is not just a hollow tube. The thoracic vertebrae and the neck anchor the muscles of the forelimbs, the former also support the ribcage; the vertebrae of loin and croup anchor muscles of the hindquarters and tail. The bony protrusions at the top of each vertebrae do not all face the same way, those anchoring the forelimb are angled to the rear, for the hindquarters they angle forward, and between are some with less pronounced, more upright ridges. Where these ridged vertebrae meet the neck, at the withers, there should be a slight dip, just before the withers.
The spine is naturally curved - there should be a slight rise at the withers and also over the loin, although the latter is often disguised under muscle, fat and coat, even in Smooths. The spine should not curve from side to side (viewed from above), nor should there by any pronounced dip or rise in the topline. Weakness of the spine results in faults such as a 'Sway back' - a pronounced sag in the spine between withers and pelvis, or a 'Roach' or 'Camel back' - a pronounced rise behind the withers. A level back should not be billiard table flat, but it should not slope, height at withers should be the same as at the croup.
Body Shape
Length of body is now specified clearly in the standard and the definition of 'back' (not entirely agreed upon in canine circles) need no longer worry anyone wishing to understand the Chihuahua standard. It should be noted in passing however, that there is no resorting to the standard to justify personal preferences for long bitches and short, 'cobby' dogs, the Chihuahua standard is totally unisex in all its requirements (except the obvious of course!)
Chest
The ribcage is an important structure, determining the room available for heart and lungs. There are 13 pairs of ribs, pivoting where they join the spine, and connected to the sternum by cartilage. The first nine pairs connect by cartilage directly to the sternum, the next three pairs are connected by cartilage to the cartilage of the rib in front, whilst the final pair are 'floating ribs' with no connection to the cartilage of the other ribs. These joints (bone/cartilage or cartilage/cartilage) allow the ribcage to expand outward with each breath, increasing lung capacity. The heart rests between the lungs on the sternum between the 3rd and 8th ribs. The ribs are set against the ribs and against the diaphragm - the muscle which runs diagonally from the loin vertebrae, down the rib walls, to the 7th rib and the sternum, separating thorax from abdomen. The action of the diaphragm creates a vacuum behind the lungs, greatly assisting breathing.
The standard recognises the need for plenty of heartroom by requiring 'well sprung ribs, deep brisket'. The ribs should spring out in their initial curve away from the spine, but then flatten and lengthen slightly to deepen the chest, the length of rib and depth of chest best increases heart and lung room. If slab-sided, with little or no spring of rib from the spine and flat sides to the ribcage, room is restricted. Rounded, 'Barrel ribs' offer an illusion of room, but adequate depth of brisket could only be obtained with a disproportionately large ribcage. As well as depth and width, the ribcage should also be sufficiently long, so the brisket line should not cut up before the 7th or 8th rib. If the brisket line rises immediately behind the elbows, at the 3rd or 4th rib, the heart is pressed upwards, reducing lung room. Depth of brisket should be measured through the tip of the sternum, not merely between the foreigns.
The tail completes the body's structure, the tail bones are a direct continuation of the spinal column, becoming progressively smaller and tapering to the rear. Control is by three quite powerful muscles, two above and one below. The set of the tail should be fairly high, to allow the tail to be carried up and over the back. A low set tail is likely to accompany a 'goose-rump', with steep croup and movement problems. If the tail is set too high, laying flat across the back like a Pom's, the pelvis is likely to be laid too flat, with resultant short, stilted hind action. A twist or kink in the tail is a fault that may be more serious than it appears, since unnatural twists in the tail vertebrae may be symptomatic of further weaknesses along the spinal column. The curly 'pig' tail, and the long tail twisted to one side, the results of muscular imbalance may also signal further weaknesses in muscular development. The typical chihuahua tail is the result of a slight flattening of the vertebrae combined with strong muscles, modifications which slightly reduce tail length. A long, round, bony, 'whippy' or 'rats' tail is a deviation from type.