SKELETON AND JOINTS
The bones, on which the muscles are attached, and the joints form the solid framework of Vertebrates.
The skeleton of the dog is divided into three parts: head, trunk and ends. The number of bones varies from 228 to 232, broken down by shape: long, flat and short, classified into two categories: odd or even. The skeleton gives the individual its general shape and size. Bones have a support and protection function of sensitive organs, and are the passive bodies of the motion, in fact the muscles (the active organs of movement) are attached to the bones that act on them as lever arms.
The skeleton of a dog (for all breeds) must be strong and in harmonious relationship to his size, more or less developed depending on the requirements of the standard.
Also in this the Chihuahua, is a harmonic and proportioned breed, the skeleton must not be tiny or weak, but not Excessive, both cases express disharmony
Joints are the union of two adjacent bones, and is a generic term for "articulation, " and according to their nature and function are classified differently. We call "real joints"or "diartrosi", those that allow two bones to stay in contact, through the articular surfaces, but allow movements determined in direction and amplitude, thanks to the slipping of an articular surface on the other.
Obviously, their function is essential to movement.
The main joints of the thoracic limbs are: shoulder joint (shoulder) (that we described in the previous issue) and humerus-radio-ulnar joint (elbow), while for the pelvic limbs are: the hips (hip) and the femoral tibial joint (knee) and ankle (hock).

MUSCLES
Muscles are organs made of contractile muscular tissue . The ensemble of the muscles and their attachment is the muscular system which is part of the motion system

There are two types of muscle, striated and smooth.
• The smooth muscles are not part of the motion system (with very few exceptions) are involuntary, and their contraction occurs autonomously under the control of hormones, external stimuli or in response to impulses from the autonomic nervous system ..
• The striated muscles: they operate as an active tool of the locomotor system. They contract in response to nerve impulses from the motor neurons in the central nervous system, on a conscious level and are connected to the skeletal segments.
The striated muscles are divided into skeletal muscle and skin muscle: the skeletal muscles have their ends attached to the bones and are the primary cause of motion, the skin muscles have at least one end attached to the skin.
Striated fiber muscles are composed of a fleshy medial side, called body, which is the contractile part, and two or more inextensible ends, called tendons, which allow the attachment of the muscle to the bone.
The muscular action in the muscular skeletal parts has as a result five essential movements : flexion, extension, adduction, abduction, circling

The concept of beauty in dog science
Solaro, famous cynotechnic and the father of Dog-science, wrote "The concept of beauty is subject to general laws, which are the emanation of the aesthetic taste of a people or of an era, but beauty in zootechnics goes beyond the sensory pleasure, and is oriented toward the intellectual pleasure. "
we have different kinds of beauty, of special interest to us is

Harmonic Beauty
In Dog-science the word "harmony" is not different than in the music expression. The harmonic beauty results from the proportions of the parts, outline and format. In other words to evaluate it we take into account some basic concepts:
1) the diametrical ratio (anamorphic) that is the relationship between the longitudinal diameters and transversal ones, the dog is balanced when they are proportionate to each other without one being dominant over the other. This is typical of the Chihuahua.
2)profiles (alloidism), which evaluates the profiles of the back of the head, rump and aplomb, we rarely find the same profile in all the parts of the dog, the Chihuahua, for example, has a convex profile of the head and straight profile of the back.
3) the format (heterometry) is given by the height and by the mass. Compared to the size, a dog is balanced when each part is attributable to the same format, namely that there are no disproportions. And this is the case of Chihuahua.
As we saw and discussed in the previous issues of AAC, the word "harmony" is a constant and influential factor.

CYNOMETRC
Zoometric is the study of somatic measurements and proportions of the body of an animal, when referred to a dog is called cynometric. The measurements of the regions and parts of the head, trunk, limbs of the dog and the relationship between these measures, help provides certainty, or at least objective data, essential to the right understanding of the standard. In other words, a description such as "wide, narrow, short, etc.." Of a given feature can be interpreted subjectively. A precise measurement, for example, the height at withers, body length and the relationship between these measures, is absolute and unquestionable. Therefore cynometric is a needful tool to Dog-science; are inseparable science to .tell precisely relationships and numerical values such as: width, length, depth, circumference. Not always, however, the standard specify key measurements, for example, the Chihuahua standard does not refer to the height at the withers, but only at the weight that has to be to be from 1.5 kg to 3 kg The fact is that by applying cynometric and Dog-science, according to the classifications devised by the various important canine scientists, we can define our little Mexican dog: lupus type, aberrant dwarf, dolicomorfo, brachycephalic
Cynometric to be applied uses as instruments: scales, cynometers, calipers, tape measure, goniometer, limb-goniometer, and the colour scale of the eyes.

If we want to study on a breed to determine its key measures, we must make measurements on the largest number and on the better subjects of that breed available, and every measurement should be repeated several times in order to obtain an average as realistic as possible. Obviously we need to know where to take measurements, namely the so-called "landmarks", or the specific anatomical points, palpable and recognizable. Zoometric measurements are many, the cynometric adopted those of interest in dogs, we're going to explore the one needed in the following paragraph:

• Height at the withers
• Scapula-ischial length
• Elbow height

The height at the withers is measured from the withers (cynometric landmark) to the ground, tangentially to the elbow, the tool that we use to measure is the cynometer. This measure determines the height of the subject, then the size of the dog, this is the main measure of reference for all parts of the dog.
The scapula-ischial length or body length is measured considering two landmarks:
1) prior to the tip of the sternum or from the external scapular tip angle
2) the only reference point on the back, the ischial tuberosity.
The tool is the cynometer.

The height of the elbow is taken with the cynometer from the tip of the elbow to the ground.

Still, there are no specific cynometric studies on the Chihuahua breed that would allow a more precise classification of the morphology. We hope that very soon, thanks to the work undertaken by the CCC with the help of dr. and Judge Murante, this gap will be closed.

PROPORTIONS
The Chihuahua is a highly sophisticated breed of great elegance and distinction, its size is compact but properly balanced, with the right proportions of mass and volume.
The fact that the Chihuahua is a small dog does not get rid the need for all the different parts to work together in coordination and balance, no connotation of dwarfism is allowed.

The head is proportionate to the trunk. The latter is cylindrical, strong, compact it looks almost square with proper development of muscle and bone structure. In females a little extra length of the trunk is allowed (allowed does not mean that is desirable). The top line of the body is straight, the lower line, comeback gently in the ventral region, therefore avoiding the obesity look.
The body has to be full-bodied with a good chest depth, but not too excessive. It is not as thin as that of an Italian greyhound, or solid such as a Pug! but still has to give a good impression of solidity.

The standard is of a body length only slightly longer than the height at the withers (... almost into the square), across the chihuahua will have to give the idea of great compactness, this feature is today increasingly sought after.
If we look at the dog from the side, the distance between the elbow and the ground should be equal to the distance between the elbow and the shoulder and the sum of these two measures should be slightly less than the distance between the tip of the shoulder and the tip of the buttock that is the "scapula ischial" length, namely the length of the trunk.
The proportions between the regions of head / neck / trunk and all sub-regions are always linked with harmony and therefore when watching a chihuahua you should have the impression of a well-balanced dog.

The zootechnic checks has to give precise indications of selection to the breeders, who must be prepared to pursue a dog as close as possible to the standard. As we have repeatedly stated, they should not be led astray by personal taste, nor by fashion, avoiding the excesses, we are not looking for ring dogs, nor for heavy dogs with the typology of a small Asian dog, nor too light and with a lack of type, selection should always aim to get the real chihuahua: harmonious and balanced.