At the gallop, and in jumping, the rear
stride must generate as much power as possible to propel the dog as
far and as fast as possible. This is a gait of maximum exertion and
stride length. To achieve this, the body folds up, roaching the spine
and bringing the pelvis as far under the torso as possible. This allows
the hind leg to reach forward well past the center of gravity (Fig 1).
If the pelvis is set on too flatly or too steeply, its ability to smoothly
fold under will be disrupted. The dog also lowers its centre of gravity
- the faster the gallop, the lower it goes. This lowered profile helps
to reduce wind resistance and makes quick turns easier, much like a
racing car. The hind leg in the support position must contract far more
at the gallop than at the trot, in preparation for a huge backward thrust,
and lowering the body enables this to occur as well (Fig 2). This is
why under angulated dogs who cannot show a roomy trot can still demonstrate
an impressive gallop. They achieve the angulation required for thrust
by dropping the entire body low to the ground. The overangulated dog,
on the other hand, cannot achieve good speed at the gallop. Such dogs
are usually too long and low stationed to begin with, and dropping any
lower would simply cause their excessive angles to collapse under them.
So the thrust they produce at the gallop isnt much greater than
the thrust produced at the trot, and neither is the speed. Needless
to say, they are not capable of really high, powerful jumping either.
  
At both the gallop and in jumping, unlike
at the trot, the rear thrust of both hind legs is generated more or
less simultaneously; the legs tend to move together. Whereas at the
trot the pelvis remains relatively stationary, at the gallop it moves
in concert with the hind legs. So too does the spine. As the legs thrust
backward, the back straightens out like a strip of steel that has been
bent, and then springs open, flattening the pelvis with it (Fig 3).
This is why the normal orientation of the spine must be straight. If
it is roached, it wont have the ability to straighten with real
power. Much of the power and length of the stride at the gallop is generated
in the spine, as one can see in cheetahs and greyhounds, whose backbones
show huge degrees of flexion. The spine may even, at the point of follow
through, arch in the opposite direction, allowing the hind legs to be
thrown back virtually level with the line of the body as it sails through
the air.
Because the gallop generates extreme speed,
the dog will expend as much energy as possible. It is not intended as
a long distance, conservative gait. The dog is going flat out in pursuit
of some wanted goal, whether it be a ball, a bad guy or escaping livestock.
At the end of the stride, at the point of maximum exertion, the hind
legs will describe a straight line from hip to toe, with no stored energy
remaining. The follow-through will throw the legs upwards almost in
line with the body, with everything the dog has surging in one line
of progression. This is when the dogs quality of muscling and
conditioning, far more so than at the trot, becomes apparent. Its
worthwhile if you get the opportunity to run your hands over a racing
greyhound, to get a sense of what professional conditioning feels like.
The mental component is also necessary however. No matter how physically
perfect, if the dog lacks the mental commitment and drive for a goal,
what Thoroughbred breeders call heart, its physical abilities will remain
untapped.
The back, whether at the trot or the gallop,
must transfer the power generated by the hindquarters forward, must
add its muscular effort to the generation of stride and power, and must
also support without buckling the entire weight of the dog across each
period of suspension. It must withstand the stress of twisting and turning,
the compression impact of sudden stops, jumping and landing and, in
bitches, the added burden of carrying a litter. It should be obvious
that faults of back structure should be considered serious. In wild
canines there can be wide variations of size, proportion and angulation,
but I have never seen a wolf, coyote or cape hunting dog with a roached,
swayed or tilted (to the front or back) backline.
Power
generated in the rear and transferred along the spine must be supported
and maintained by the forehand. However, the dogs front doesnt
just passively carry the weight of its front half. It must be able to
absorb the energy generated from the rear without dissipating or interfering
with it. It provides the brakes and the steering, and even generates
a degree of propulsive power of its own. The length of stride of the
forelegs must match the length of stride of the rear legs (Fig 4). Each
front leg must be able to reach as far forward as each rear leg, as
well as drive back and follow through to the same degree. To do this,
the dog must posses a well angulated shoulder blade and upper arm, as
well as a high, well muscled wither to provide leverage and a wide bed
of muscle for effective rotation of the scapula blade. Both front and
rear paws must strike the ground at the same angle, for the degree of
impact to match. They must show the same amount of contraction in the
support position and the same degree of follow through. Without an excellent
front, the dog wont enjoy the advantage of an excellent rear.
While much is usually made of the necessity
for a good shoulder, excellent withers are often overlooked. High withers
provide the attachment for a good shoulder, and enable the blade to
move sufficiently far forward and backward for the foreleg to show good
reach and follow through (Fig 5). As well,the broad shoulder attachment
provided by a high wither means a wide harness of muscle about the dogs
forequarters, literally a sling in which the full weight of the dogs
front half is carried. In jumping, this sling must catch the dogs
total weight, and absorb and distribute it evenly. When the dog stops
suddenly, it jams its forelegs into the ground to brake itself. If turning
abruptly, it does the same and then vaults its weight in the desired
direction (Fig 6). In both cases, the shock is directed through the
shoulder blades, into the withers and along the back. Other species
which specialize in jumping and maneuverability, such as impala and
pronghorn, show long, high, powerful withers. The broad muscling provided
by high withers is also carried well up into the crest of the neck,
and provides the foundation for the power a dog needs when driving into
the grip (Fig 7). The hyena, probably possessed of one of the most powerful
grips in nature, isnt so much an animal with a disproportionately
small hindquarter, as one with massive jaws, skull, neck, withers and
shoulders, all supporting the incredible bite pressure it is able to
generate.
  
Good
reach and support is also aided by a good prosternum, that point of
bone (actually cartilage) in the center of the dogs forechest.
To this process is anchored a fan of muscles that spread up either side
of the neck and pull the head down, and across both points of shoulder
and the upper arms (Fig 8). These muscles draw the shoulder joint and
humerus forward, and the foreleg inward, and are part of the sling that
supports the weight of the chest. Better leverage is achieved when the
point of sternum is positioned slightly ahead of the point of shoulder,
as seen from the side (Fig 9). That way, the prosternum can better act
as a guide when drawing the shoulder forward, especially at the trot.
At the gallop, the dog throws its entire fore assembly forward
well past the sternum, with reach that is much higher than we want at
the trot. It uses a great deal of of energy, but it achieves a huge
stride (Fig 10). Too much prosternum makes the dogs chest appear
to protrude, and interferes with its ability to maneuver sideways. This
sort of structure seems to go hand in hand with chests which are far
too deep and narrow, more like the keel of a boat, and a hindrance to
agility.
 
When
viewed from the front and rear, the stride should give the appearance
of single tracking, with the paws converging towards the centre line
of the body while the legs remain relatively straight. This requirement
shouldnt be taken too literally however. First, the leg which
is in contact with the ground, supporting and driving the dogs
weight, should be as straight as possible from the shoulder or hip to
the ground. Any tendency for the joints to buckle or twist both waste
energy and greatly increase the legs vulnerability to injury.
The other leg, the one moving ahead, need not be totally straight. This
leg is bearing no weight or stress. In fact, the contraction of the
leg whether front or rear, while being lifted bunches the muscles and
will tend to bring the leg away from the center line. The more heavily
muscled the dog, the more this tendency is apparent (Fig 11). Too much
emphasis on a precise, single tracking gait will produce animals with
flat, thin muscling and narrow bodies, as has already happened in some
show lines.
Single tracking is really just an impression
given by the convergence of footsteps towards the center line of the
body. The animal doesnt really walk with its footsteps falling
along a single line, like a tight-rope walker. In fact, the GSD when
moving correctly at the trot actually triple tracks (Fig 12).

True single tracking would require the
stride to be so short that the footstep of the rear fell short of the
footprint of the front, a gait typical of many terriers (Fig 13). Double
tracking appears when the dog either moves wide in both front and rear
(Fig 14), or shows a crabbing action, with front and rear single tracking
on separate paths (Fig 15). Triple tracking, while it may sound bizarre,
actually allows a long overreach of the rear past the front, without
necessitating a crabbing action, as the three lines of progression are
very close together and to the centre line of the body. For instance,
the right front foot may travel its own path, the left front and right
rear feet will track the same center line, and the left rear foot will
follow the third path. In this case, the dogs rear end will be
slightly shifted to the left (Fig 16). The pattern may be reversed and
the dogs rear shifted to the right. Interestingly, the Belgian
sheepdog standard recognizes this when it states that the dog, at the
trot, shows a slight tendency to move in a wide arc to the left or right,
rather than in a perfectly straight line. The lines of progression are
barely a paws width apart, only enough to allow the feet to pass
each other without interference, and one must look very, very closely
to see that the body itself is a degree or two off the straight. Without
the ability to triple track, the dog cannot achieve the length of stride
required for the flowing, effortless trot that is so unique to this
breed.
   
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