First, you have to have a mental image of a perfectly correct “square flank”. This involves the relationship between the dog and SHEEP not the handler. Dogs do not square flank off the handler, they square flank off the sheep. As the dog runs in half circle or part of a circle around the sheep they are presenting their SIDES to the sheep. To be square the sheep should never have a front shoulder view which would mean the dog is spiraling in and not staying on the same arc it started moving on.
Dogs should move only in two ways – flanking and walking up. They shouldn’t angle in. Flanking doesn’t move sheep, walking up moves sheep. Flanking is to put the dog in the correct position so when they do walk up the sheep go in the direction desired. Flanking doesn’t change direction of sheep – sheep should not be moved by the flank.
To make a square flank when the dog is looking at (and facing the sheep) the dog pulls its shoulder back away from the sheep until the side is toward the sheep and then they begin to move in the arc around the sheep. For definition purposes there should be no forward movement of the dog toward sheep while making a square flank. The arc should stay exactly the same distance from the sheep unless the dog is told to stop and walk forward moving the sheep.
The lack of square flanks becomes magnified when only slight adjustments are needed in direction such as at a free standing pen or driving to a specific point.
When an outrun becomes lengthy the dog would waste energy running in a full circle curve from his starting point to the same distance behind the sheep. This is where the dog runs on a course that looks like a “pear”. The dog is still running “off the sheep” and should not be running off the position of the handler. With such distances the dog’s side is to the sheep. When the lift or walk up is made the dog turns into the sheep so the sheep see the front of the dog.
With “eye” dogs their bodies will change from the flank to the lift or walk up by curving. An upright less flexible dog may actually plant its front feet and have the hind quarters lift and swing 90 degrees to go from the flank into the lift or walk up. No matter how the dog physically performs the square flank the results should always be the same – no movement of the sheep caused by the flank. And, the dog always pulling itself back and to the side to begin a flank if facing the sheep.
Square flanks are very important in arena trials especially those where the sheep are not real familiar with the course. In the tight spaces of an arena the dog must have the ability to take its forward pressure off the sheep entirely in order to make the small changes of direction necessary to make the obstacles and drive smoothly along the fence line regardless of pull on the sheep.
The arena outrun is somewhat different than the field outrun where there are no constraints. If a dog in an arena was to follow its desired path to get it behind the sheep it would come to the fence about in the middle of the Y chute, for example, and stop because it could no longer run on the path that would put it correctly around the sheep. Dogs are trained to be allowed to continue their outrun along the fence which they should hug tightly. Ideally, as the dog passes the pressure pull point (typically from set out food pan to gate) the dog would slow just slightly, look at the sheep to remind them to stay put and then move behind the sheep to the fence. The curve around the sheep from the side should not start until the dog has passed the side of the sheep (at the pan) and should continue to behind the sheep or point of balance behind the sheep at the fence if this truly is the point of balance. This should allow the dog to have as much room as possible to make a correct quiet controlled lift; then if the sheep opt to pull to the side there is time to flank the dog during the fetch to keep it straight and make the turn around the post correct. There ARE certain skills that must be taught or reinforced for arena situations but all the basics of good stockdog training and stock handling are used.