Construction d'une bonne épaule
Construction d'une bonne épaule
le 1er cliché est celui d'une bonne construction d'épaule
Les 3 autres clichés montrent les mauvaises constructions d'épaule.
le 1er cliché est celui d'une bonne construction d'épaule : bien angulée
Les 3 autres clichés montrent les mauvaises constructions d'épaule :
cliché 2 : Type A, Straight in Upper arm : épaule droite dans la partie inférieure.
cliché 3 : Type B, straight front : épaule complètement droite .
cliché 4 : Type C, straight in shoulder blade
un lien intéressant concernant les chiens de compétitions de type lévrier : https://www.thedogplace.org/BREEDS/Irish-Wolfhound/Canine-Shoulder_McClure-1202.asp
le texte est en anglais mais vaut la peine d'être lu.
un autre extrait :
About the Front Assembly
A dog's front assembly determines the amount of reach he will have when moving. It also determines -- at least partially -- how clean, correct and efficent his front movement will be. (Front movement is also determined by length of body and the similarity of the dog's front and rear angulation.)
When going over the dog's front assembly, one looks for the following characteristics (among others):
Length of upper arm or humerus: As you can see from the diagram at left, the dog's upper arm (humerus), should actually be slightly longer than the shoulder blade (scapula). Most people assess length of upper arm by using three reference points that can be easily located (even when covered with skin and hair). These reference points are the top of the dog's shoulder (point A in the diagram at left), his point of shoulder (B) and the tip of his elbow (C). Putting your thumb on B, you can reach the top of the shoulder (A) with one of your other fingers. Keeping your hand in the same position (keeping the same spread between thumb and finger), swing down to the tip of the elbow (C). The second distance measured -- B to C -- is somewhat shorter than the true length of the upper arm; but if the upper arm is long enough, the distance from B to A should be the same as the distance from B to C. If the distance from B to C is shorter than the distance from B to A, the upper arm is too short. This common structural problem can result in less reach when moving (an inability to swing the leg forward the optimum amount in order to cover the most ground). It can also result in inefficent movement, such as lifting the front feet too far off the ground with each stride (the front feet should just clear the ground as the dog moves -- anything more is wasted motion).
Layback of shoulder: When going over a dog's front, most people estimate shoulder layback by placing the thumb at the point of shoulder (point B in the diagram) and one finger at the top of the dog's shoulder (point A) and figuring the angle of that line (B-A) off the vertical (line E-B). Using this method, you can see that the dog in the diagram has a shoulder layback of 30 degrees. Many standards, including the Sheltie standard, call for a shoulder layback of 45 degrees. This angle was derived from what the standard-writers knew about horse anatomy, where well-laidback shoulders make for a smoother ride. Unfortunately, good front assemblies in dogs and horses are very different. The front assembly a rigid-backed horse needs for optimal gait (the comfort of a rider being the primary consideration) has little relationship to the correct front assembly in a dog, which has a flexible back and is not ridden. Research has shown that the best-moving trotting dogs have an average shoulder layback of 28 degrees, plus or minus 5 degrees. Galloping dogs (sighthounds) have considerably steeper shoulders (more like 15-20 degrees), while diggers (such as Dachshunds) have greater layback than trotters. Shelties are trotting dogs.
Insufficient layback -- sometimes referred to as "a straight shoulder" -- is a widespread problem in Shelties. When moving, dogs with insufficient layback lack reach. This can lead to other movement faults, especially if the rear is better angulated than the front -- a common problem -- causing the drive from the rear to be better than the reach in the front. Such dogs will have a longer stride in the rear than in the front and will have to find a way to compensate. One possible compensation is to lift the front feet too far off the ground with each stride. This is wasted motion, but it enables such a dog to "get out of his own way." The dog may also fail to single-track (feet converge toward a center line) in front, so that his rear feet -- which are single-tracking with good, long strides -- can swing between his lifting, non-single-tracking, short-strided front feet. (Some people call this type of a movement a "reverse tricycle" -- i.e. two "wheels" in front, one behind.)
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The All Important (and Neglected) Upper Arm
sur le site du United Kennel Club
https://www.ukcdogs.com/Web.nsf/News/TheAllImportantandNeglect12162009032438PM
Richard G. (Rick) Beauchamp
There is no doubt that the fanciers of each and every breed find theirs to be "like no other", and in some respects this is absolutely true, and it is exactly why we have so many different breeds. Each has its own distinctive charm or as the French would say raison d'être - reason for being.
Because breeds are so distinctive in their character and construction, their devoted owners are apt to think of their canine of choice as different in all respects, including anatomy. As difficult as it may be to conceive, our entire dog breeds - from Great Dane to Bulldog - are constructed with exactly the same set of bones. It is only how those bones are shaped and how they lie in relationship to one another that give our breeds their distinctive shapes and sizes and ways of moving about.
When you think of what man has wrought - from Canis Lupus, the wolf, to Bulldog, Irish Wolfhound and Chihuahua - you can't help but marvel at how ingenious he has been through the ages. Those of us who struggle and complain about the difficulty in trying to fix a trait in our breeding programs should pause a moment to think about from whence we came - wow!
The study of canine anatomy and locomotion applies to all of our breeds, and the principles that govern canine locomotion remain the same for all of the breeds. It is important for the breeder and judge who are trying to determine why a dog looks and moves as it does to remain aware of this fact.
If there is a universal fault apparent in the North American show dog it is, without a doubt, in the front end of the caboose. It is interesting, however, that when there's talk about building good fronts on our dogs the conversation is most often inclined to confine itself to layback or angulation of the shoulder.
Correct respective shoulder angulation is certainly not easy to achieve, but the shoulder is not alone when it comes to achieving correct front construction. Not enough consideration is given to the return and lay of another very important bone in the front assembly--the upper arm.
The upper arm, or humerus, as it is technically called, is the bone that is attached to the shoulder joint (scapula) at its upper end and to the forearm (made up of the radius and ulna) at its lower end forming the dog's elbow. The upper arm varies considerably in size, length, curvature and placement according to the respective breed.
In tall breeds like the Borzoi, Irish Wolfhound and Great Dane, the bone is very long and it curves gently both toward the rear of the dog and inwards toward the curvature of the dog's rib cage. In the achondroplastic breeds like the Pekingese, Dandie Dinmont Terrier and Basset Hound, the upper arm is considerably shorter and more sharply curved both to the rear and inward toward the rib cage.
In the long legged terriers like the Fox Terriers and the Whippet the upper arm is shorter and straighter, but still curves inward in line with the dog's chest type. This brings the foreleg considerably further forward on the dog's chest resulting in a flatter profile to the outline created by the forechest. When this feature is extremely exaggerated, as in the Wire Fox Terrier, the dog's stride of the front legs is shortened, while this appears far less so in the Airedale because the feature is not quite so pronounced.
Just the opposite is true of breeds like the German Shepherd and a number of the Gun Dog breeds - in fact the majority of breeds - where the upper arm is fairly long and "returns" well back on the chest bringing the elbow distinctly rearward so that the elbow in many cases ideally sets in a straight line directly below the highest point of the withers. In breeds where this construction is appropriate, you find judges and breeders looking for the dog that has "good return of upper arm".
The characteristic is most exaggerated in the German Shepherd, which accounts for the great forward stride of the front legs, and not so much as what one might find in a less exaggerated example of the construction in breeds like the Doberman Pinscher.
The Spaniels and Retrievers are considered ideal examples of upper arm efficiency. In fact, everything about the breeds in these two classifications comes under the heading of ease of motion. The breeds are required to cover great distances at a steady, easy and ground-covering trot.
With all this said, a word about efficiency is warranted here. Over the past several decades there has been a trend - no, make that a fad - to make all breeds efficient, even the ones whose very creation was based on inefficiency.
The bowed legs of the Pekingese were developed so that the dogs would not easily trot off the palace grounds. Foremost in the developers of the Bulldog's conformation was a low center of gravity (to hold the bull's head down), not the ability to trot around town all the day. The high stepping mincing movement of decorative breeds like the Min Pin was unique and fancy - another reason for the ladies of the day to be attracted to these lap dog breeds.
I've digressed here, but we must realize the whys of the creation of our breeds. I shudder at the effect of the recent attempts of The Kennel Club in England to "iron out" the breed standards. Their actions will have no other consequence but to create a major generic landslide. Perhaps the august organization might give thought to what those who established our breeds might have had in mind rather than attempting to placate the criticism of the animal rights radicals.
To return to the subject at hand, however, in a number of breeds the short, straight upper arm creates a tendency to lift the forelegs in a hackney-like motion. This is required in the breed-identifying gait of the Miniature Pinscher and, to a lesser degree, in the Italian Greyhound. It would, however, represent a glaring fault were it to be found in the Whippet or Greyhound. The distinctive gait of the Japanese Chin (lifting its forelegs well clear of the ground without any bend at all between elbow and toe) is unique to that breed.
Interestingly, as important as the length of the upper arm is, and how important it is to the movement of the Min Pin, IG and Chin, none of these standards even mention the forearm upon which the desired movement is entirely dependent.
Richard G. (Rick) Beauchamp has been successfully involved in practically every facet of purebred dogs: breeding, exhibiting, publishing, writing. He is the author of numerous breed and all breed books including the best-selling Solving the Mysteries of Breed Type and Breeding Dogs for Dummies. He has judged all breeds throughout the world and was one of the United Kennel Club's first all breed judges.