Structure As It Relates To The Performance Dog
By Nina Plail
As agility becomes more and more popular, the need to understand and promote good conformational structure becomes increasingly important. Neither breeders, nor exhibitors, want to find themselves in a position where a performance prospect is trained to the highest levels, only to breakdown midway through a competition career.
In the recent past, many performance prospects came from conformation breeders who, for varied reasons, decided that a specific dog was not suitable as a conformation prospect. As our sport continues to grow, demand is created for dogs who are designed to withstand years of competition, thousands of repetitions and the mental stresses of competition life. We are able to influence long run breeding decisions by becoming knowledgeable, informed purchasers. Exhibitors and breeders need to be aware of structural issues and how they pertain to the agility dog.
There are several key factors to consider when evaluating structure. Some structural issues vary from breed to breed, with differing requirements for angulation, depending upon the type of work a specific breed of dog was bred to perform. This discussion cannot address the various breed standards for each and every breed, but rather will focus on issues pertaining to the majority of the breeds competing in agility today.
One physical characteristic worthy of consideration is length of leg. The length of a dogs leg from the ground to the elbow should be longer rather than shorter. Adequate length of leg greatly aids a jumping dog. However, moderation should be considered here as a dog excessively high on leg has a higher center of gravity and can tend to be less stable. A dog moderately high on leg would be ideal.
The problem with inadequate leg length is twofold. First, small/short legs contribute to a less than desirable weight to height ratio. Second, small/short legs are much less efficient and have to work very hard to propel the body over jumps, through weave poles and over A-frames.
Next, one should consider the rear assembly. A dogs rear should be strong, well angulated and should have stability of hock.. While good front end angulation often eludes the breeder and exhibitor, good rear angulation is more prevalent and thus should be relatively easy to find. Beyond the technical analysis of proper angulation a good rear can be evident to a minimally trained eye. A dog with a good rear will automatically “set up” correctly when naturally standing. These are the dogs who self stack in the breed ring, or who stand naturally with rear legs firmly and strongly planted to the ground. The stifle is well defined and pleasingly curved. The hock joint is also well defined and the hock itself is perfectly perpendicular to the ground. Any disturbance in rear angulation will bring the back feet either too far under the dog, or too far out behind the dog and thus, the hock will not longer sit perpendicular to the ground.
Technically, the rear angulation described above is achieved when a line drawn perpendicular from the ground forms a 45 degree angle with the stifle bone Figure 1, angle a). In addition, the angle where the femur meets the pelvis bone should be 90 degrees (figure1, angle b). It is this proper angulation that allows the dog to propel him self by reaching up under his body with his rear legs. Technically, this aspect of movement is called “Drive” as opposed to front end movement where the dog extends his front end out in front of him as he “reaches”. Good reach and drive are very important characteristics for a performance dog and are achieved, in part, through proper angulation.
In addition to the major components of the rear assembly, consideration should be given to the feet, which, in several breeds, should be compact. Long thin toes are subject to injury when they get hung up on slats and various other perils in the performance world.
At least as important as rear angulation is front end angulation. Proper front assemblies are very important to the performance dog. The front end bears over half of the weight of the dog as he performs. With respect to jumping, a strong rear launches the dog, but the front end bears the majority of impact while landing. When ascending the A-frame, the front end takes the initial impact. The front assembly also bears significant impact in striding down and landing when performing the A-frame and the dog walk. Unfortunately, nice front assemblies are a lot more rare than nice rear assemblies. To complicate matters further, dogs with very nice fronts do not reproduce them as readily as other virtues. Nevertheless, a better than average front should be a requirement for any serious agility contender. Overly “straight” fronts have caused many talented dogs to end promising careers early.
There are several variables at play, all working together to create the front assembly. When evaluating the front end of a performance prospect consider the extent of shoulder layback. Layback is accessed by locating the withers and analyzing how far these withers lay back towards the back of the dog. Withers that creep up onto the neck of a dog create a short necked dog and a dog who is also straight in the front. Technically, a line drawn perpendicular to the ground, touching the post sternum should form a 45 degree angle with the line from the withers to the post sternum (figure 1, angle c). The shoulder is the bone in between the post sternum and the withers, so when the angle is appropriate, the shoulder blade lays back toward the rear of the dog, as opposed to more vertical. The straighter the shoulder, the more vertical this bone will lay. The bone from the post sternum to the elbow is called the upper arm. The upper arm should also meet the same perpendicular line (front the ground to the post sternum) at a 45 degree angle. Thus, the front assembly is comprised of two 45 degree angles (angle c and d), which together form a 90 degree angle. It is important to note that full shoulder layback is not achieved until maturity, however, a good degree of layback and angulation should be evident in an 8 week old puppy. One important thing to remember is that the length of the upper arm should equal the length of the shoulder. One should also note that when a dog is described as having “length of neck” this necessarily means that the dog has good shoulder layback, thereby having a greater number of vertebrae above the shoulder, rather than tucked away under the withers.
As we see in the diagram, the post sternum is an area where bones meet, angulation is required and prominence is preferred. Many of the muscles powering the front end attach themselves to the post sternum, as such, a prominent post sternum should be evident even at puppy hood. The posternum should be an obvious extrusion that can easily felt when running ones hands across the front of a dog. If a dog feels flat between the front legs and the neck then such a dog likely has insufficient post sternum.
After considering the front and rear assemblies individually, one should analyze them as two pieces of the same machine that will need to work in unison. There is a common belief in canine structure that angulation should be balanced front and rear. When running, jumping, twisting and turning, the front and rear work together. An over angulated rear with a straight front will cause a bouncy, choppy movement as the front legs hit the ground too soon do to lack of extension. This creates a lot of stress on the front and is a very undesirable combination for a performance dog. It would be more preferable to have average front and rear angulation than to have fabulous angulation in the rear and average angulation in the front.
In between the front and the rear are several body parts that are worthy of discussion from a performance stand point. To begin with, the chest should be somewhat broad and the front legs should not be spaced too close together. This allows for lung space and aids in endurance. Elbows should generally be close to the body thus aiding the feet in pointing straight ahead, rather than in or out. The pasterns should be strong and only slightly tapering to the ground. Overall body length should be moderate. Too short of a body detracts from reach and drive. Too long of a body can lead to back problems.
In concluding, I feel the need to emphasize that the angles and analysis described is the ideal for several breeds popular today in the sport of agility. Some breeds require different angulation, and value different virtues. Even among the breeds commonly competing today in agility, there are no perfect dogs. There are, however, individuals within each breed, who closely approximate the ideal. By choosing wisely, and considering what can and cannot be compromised, performance exhibitors can exert pressure and help ensure that structural issues are important variables in breeding programs and that individual dogs chosen for a competition life are able to compete for many years after they are trained to the highest levels.
About the Author:
Nina Plail is a breeder of Shetland sheep dogs and an exhibitor in agility, herding and conformation. Nina is an AKC agility judge and owns three Versatility Champion Shetland Sheepdogs. Her dogs are competing throughout the country in several venues. She can be reached at: sheltieranch@aol.com, and maintains a web site at www.sheltieranch.com.