When people start training their dogs a service dog or assistance dog candidate, I recommend that they start early on with two behaviours that are essential for every service dog. These behaviours are often confused for two similar, but different behaviours. Let's take look at the difference.
Down Stay vs Settle/Relax
Most pet dog classes teach a formal down and stay behavior. This is because the origins of older dog training comes from the military where they had strict adherence to formal obedience and dogs were drilled on the behaviours. This is a formal behaviour that involves the dog laying in a sphinx position (dog staying very still with front feet extended and rear feet tucked under the body and the head up). Formal down stays take much focus and energy to maintain. Even the best-trained dogs cannot hold the down stay position for very long. Formal competition obedience only requires a 3 minute down stay. Pet dogs and service dogs don't actually need a formal down stay.
What both pet and service dogs DO need is a settle or relax behaviour. A settle/relax allows the dog to get comfortable on the ground. That's it. The dog can determine what is comfortable. If that is laying with their one hip rolled under them, laying on their side or laying on their chest like a frog or bear rug, that works.
The difference is that a settle/relax can be done for long periods because the dog is comfortable and can move around. Most service dogs work 4-8 hours a day or more away from home, often more at home. Like us when sleeping, our dogs move around. It is not reasonable for a handler to expect a pet or working dog to maintain a down stay for periods. The dog can stay relaxed yet still be alert for doing his job, or he can fall asleep but is still nearby. In a settle/relax, the dog can shift around on the spot, as long as he stays low on the ground. Many handlers use a towel or yoga mat to let the dog know the space that he has to move around on.
Some handlers train a 'park' cue that means the dog can get up and turn around as long as he stays on the designated spot (mat). More movement is allowed for a 'park' than a settle/relax.
The only time a settle/relax might not work is if the dog needs to curl up into a small ball to avoid being stepped on or if placed in small spaces like under a seat in a plane. Then they are also taught 'under' and 'curl'. Two more useful behaviours.
It is a great compliment when someone observes a handler leaving a restaurant and exclaims "I didn't even know there was a dog here until you got up to leave!" A settle/relax allows an assistance dog to be out of sight.
Heeling vs Loose Leash Walking
Another often taught behaviour in pet classes is the formal heel. It too has the same history as the down stay. Heeling involves the dog staying very close to (a few inches a way) or in physical contact with the handlers leg or wheelchair. In some styles of heeling, the dog also holds his head upright rather than looking forward. This is very hard on the dog's neck. Turns (left and right) are controlled with cues.
Heeling, like the down stay, is also a very difficult behaviour for a dog to sustain for long periods. Even highly trained competition dogs only do a formal heel for 5 minute periods. Heeling is only used with service dogs in specific situations such as when moving through narrow areas with many people (crowds or aisles in a store) then the dog is released to go back to loose leash walking after the obstacle or group is passed.
In loose leash walking, the dog can move within 24 inches of the handler and turns with the handler without cueing or leash tension or direction. The dog may be in front of, beside or even behind the handler, as long as they stay with 24 inches of the handler's leg or wheelchair. Quite frankly, we would not want a dog to heel very close to a chair or other medical device as they risk getting their feet run over or getting knocked into it. The extra distance from the handler allows the dog to safely navigate around storm drains, curbs, posts without affecting the handler's direction or movement in space. The dog can also move to the end of the leash to retrieve dropped objects for the handler as they move along.
Service Dog Training Institute offers classes each month on both Settle/Relax and Loose Leash Walking because they are important enough to do so. Registration runs the first wed to the second wed of each month.