Heel Halt Sits

During an obedience heel pattern when you stop your dog must sit automatically.

There are a lot of aspects that go into the automatic halt-sit that I will not discuss in this post. I will however, mention them briefly, so you can keep them in mind:
(1) Sitting at the heel-halt is not in any way natural to your dog, or something that he would figure out how to do on his own. So this behavior must be taught.
(2) Your footwork coming-to-the-stop must be the cue for your dog to sit, not your stationary stopped position. If you make your stationary stopped position the cue, than when you halt, your dog will wait until you are stationary, and than he will sit -- this results in a slow sit. Rather you want your LAST STEP to be the cue. This is accomplished by using consistent footwork on your halts and teaching your dog to sit on your last step. You can use lots of different types of footwork for the halt, the key is to be consistent. Here is what I do: The judge says "Halt" I plant my left foot (foot closest to my dog), I take a half step with my right foot, and I bring up my left foot to my right foot. I practice until I can do this footwork naturally and than I teach it as the cue to my dog to sit.
(3) You want your dog to sit straight. Crocked sits at the heel-halt can be a sign of heeling issues. For example a dog that crabs while heeling will often sit with his butt out (away from handler) and his front end in (in correct position). So if you have consistently crocked sits work on fixing your dogs heeling.

What I want to talk about in this post is the three different ways that a dog can sit on a heel-halt, what you want to look for, and what to avoid.

The three ways a dog can sit on a heel-halt:
(1) The correct sit (sometimes called the gliding-sit) :
When cued that you are stopping the dog will plant his front legs and either tuck in or scoot in his rear to meet them.
(2) The roll-back sit:
When cued that you are stopping the dog will sit down with his rear and either roll back and/or move his front legs back toward his rear.
(3) The sink-down sit:
When cued that you are stopping the dog will plant his front legs and rear legs and slowly fold the rest of his body down into a sit.

The results (video of only the correct sit will be shown since I don't want to hold any one's dog up as an example of an incorrect sit, however if you search youtube for "AKC or UKC obedience" you will find many examples of dogs doing incorrect sits):
(1) Correct Sit (or gliding sit): Fast, clean, dog maintains heel position.

(2) Roll-back Sit: Slow, dog rolls back out of heel position. Though any breed can sit in any way this type of sit is commonly seen for breeds like: German Sheperds, Large dogs like: Newfoundlands, Malamutes, St Bernards, Bernese Mountain Dogs, etc...
(3) Sink-down Sit: Very slow, almost painful to watch. Again this sit is not breed specific but it is often seen for breeds like: Great Danes, various hounds, including sight hounds.

Without discussing why certain dogs may prefer to sit in a certain way lets launch right into how you fix or avoid these problem sits. If you have a dog that is already sitting incorrectly or you have a breed that is prone to sit incorrectly. Take extra steps to ensure that your dog understands the precise mechanism for sitting. There are really just four extra things to focus on.
Make sure your dog:
(1) Sits with head up. - not up and back, but up and UP. When you are first teaching your dog to sit you may have lured him into a sit by holding a treat above his head. If you hold the treat too high the dog may jump for it. If you hold it too low, you will find that you have to move it backward above the dog's head for the dog to sit (a result of the dog following the treat with his eyes as it passes over his head), this will actually cause the dog to do and to learn a roll-back sit. If you hold the treat in the right spot, treat is held stationary above the dog's head just above the dog's brow line, the dog should sit (with even a tiny bounce up). If your dog having trouble sitting correctly go back to re-teaching him to sit, make sure that if you are luring with a treat over his head that the treat is held in the right spot. No matter how you decide to re-teach the sit make sure your dog understands that he should sit with his head held up. Rename this behavior if you need too. Also watch dogs in the ring dogs that roll-back sit and sink-down sit, you will notice that they ALWAYS drop their heads before doing the incorrect sit, by requiring your dog to keep his head up you will make it harder for him to preform the incorrect sits and make it easier for your dog to do a correct sit.
(2) Sits with legs square. - Your dog's legs should be tucked underneath his body when he sits. Dogs that do a sink-down sit often splay their legs outward. A platform can be a very useful tool to use to prevent or remedy this incorrect splaying of the legs while sitting behavior. A platform is any raised level surface (for example a rectangular wooden board on little wooden legs) that is just large enough for the dog to sit on, when he is sitting with his legs tucked under him. By teaching your dog to sit on the platform it is really easy for him to understand that splaying his legs is not the behavior you want because it will result in him falling off the platform.
(3) Sits with chest out. - By requiring your dog to sit with his chest out you are enforcing the scoot-your-rear-toward-your-legs behavior and discouraging the roll-back sit behavior. The method that worked best for me to teach a dog to sit with his chest out was to physically put him into this position. I use the word "set up" and the physical manipulation method that Sylvia Bishop teaches. Briefly; you look to your right (this aligns your shoulders correctly) you reach your right hand across your stomach and get hold of the dog's collar under his chin. You place your left hand on the dogs shoulders such that your palm is open and your thumb is on the dog's right shoulder blade and your fingers are on his left shoulder blade. Than you lift up with your right hand (dog's collar) at the same time you push forward with your left hand (dog's shoulder blades) I give the "set up" command at the same time (Sylvia uses "feet"). This is not a correction, not a cue, and not a command that the dog learns to obey on his own. But by consistently placing the dog in the correct alignment it helps them learn how to pop their chest out. The command word "set up" is really just to let the dog know what I am doing when I start to push on them. I was skeptical of this technique at first but it has worked very well for me.
(4) Sits in correct position. - By enforcing correct heel position and requiring that your dog sit in the correct place when you stop you will avoid a roll-back sit that causes your dog to roll back out of position. To do this use a treat or toy and let your dog see it as you begin your heel-halt footwork. Make sure that the only spot you give the reward to your dog is in "exact" heel position -- this will make this a valuable spot for your dog to be in and will result in him figuring out a way to sit so that he ends up there.

The video above comes from http://www.gettoready.net/ a wonderful site by Catherine Zinsky that contains articles about all obedience exercises, videos of exercises, quizzes on rules (for novice, open, and utility) and a marvelous jump height calculator.