Page 41 - ShowSight Presents The Rottweiler

Mechanical Advantage
As with bench pressing weights, the greatest push or kick comes just before you fully extend your arms. This is because the joint’s mechanical advantage over the weight or opposing force increases as the joint’s angle opens. For our dog, the full extension of his joints gives a powerful push at the end of their stride. This is why draft animals are usually straighter angled.
Trotting breeds having too long of bones (very angulated), do not have enough stride length or foot contact time to fully extend their joints before the end of phase two. Because of this, they do not benefit fully from mechani- cal advantage. These dogs, who look like loaded springs while standing, will use more energy with each step, and because of this, they will have less stamina.
Taking Advantage of Both Conditions
So the trick in determining effective rear angulations is having rear bone lengths long enough, correctly proportioned and correctly positioned to maximize the foot’s contact with the ground. While at the same time, making sure they are short enough to fully extend at the end of phase two in order to fully benefit from the increase in energy mechanical advantage provides.
It is a balancing act and this explains why the more moderately angulated dogs have the better sustainable rear drives! Their bone lengths are just long enough to allow the foot plenty of contact time to push off the ground and yet short enough to fully extend the joints allowing for max- imum benefit from mechanical advantage.
Net Extension
Another area of importance is the net extension applied during the back reach in phase two. The net extension is the measured difference between the distance from hip joint to the paw at the begin- ning of phase two when the rear angles are closed and the distance from hip joint to the paw at the end of phase two when the rear angles are open. Net extension is a key component to determining the amount of rear drive a dog can generate. This is where rear angulation has proven 228 • SHOWSIGHT MAGAZINE, AUGUST 2014
to be deceptive. Many times dogs display- ing less angulation while standing possess greater net extension than dogs displaying more angulation while standing. Because, the only angulation which can be opened in phase 2 is the angulation which is closed in phase 1. If the length of phase 1 or 2 are shortened or compromised, it lessens the net extension. When phase 1 is shortened, less bend between the stifle and hock joints is created and results in less bend opening in phase 2. When phase 2 is shortened, there isn’t enough length of back reach to fully open the bend created in phase 1. This is why phase 1 and phase 2 are equally important in creating rear push.
Pelvic Slope’s Effect on Angulation
The angled slope of the pelvis helps determine the angulation you see when the dog is standing. Dogs having the same proportions and length to their
bones of the rear assembly, can visu- ally display different angulation depending on the slope of their pelvis. Notice the chang- es in the amount of angulation associated with the different pelvic slopes in the figure below. A dog with a steeply angled pelvis will display more turn in the stifle and hock than dogs having more a moderate or lesser angled pelvis. Again, this is dependent upon all bone proportions being the same.
Another point the figure demonstrates is how pelvic slope controls the balance and lengths of phase 1 and phase 2. It is this con- trol of the working arc of the rear assembly that makes the pelvic slope one of the most important aspect of the rear assembly.
So, looking beyond the angles of the stifle and hock is important for accessing the true angulation of a dog’s rear!
To re-iterate, over angled rears are a struc- tural weakness robbing our breed of opti- mized strength and endurance. This should never be tolerated in our Rottweiler!
The Effect of Pelvic Slope on the Angulation and Working Arc of the Rear