Think about smoothness...proprioception is all about smoothness. You are able to pick up your coffee cup and drink from it, with out spilling (most of the time), and you make it look like you've done this before. And you have done this before, almost everyday. You have trained your muscles, through proprioceptive memory, to pick up a cup filled with an unknown amount of liquid and to lift it to your lips, tilt it just so you can get to the liquid, and then put it back down on the table. This little feat is amazing when you break it down to think about it, because we don't think about it. Proprioception is a learned response by our muscles to a stimulus, that we don't have to think about. It's is awesome, and very helpful.
Our dogs, actually every animal with muscles, functions through proprioceptive memory for movement. Our dogs don't think about every step they take, they just pick a direction and go, let proprioception take care of the fine details of moving each paw without running into the other three.
So, proprioception is a very important thing and saves our brains from having to worry about the little things, like moving. What happens to it when we break our arm playing ultimate frisbee (or typing, or something else crazy), and our arm is in a cast for 6 weeks? Well as soon as the cast comes off and you go to pick up that familiar coffee mug, things feel.....different. You are still able to lift, tilt, sip and enjoy your beverage, but things in your arm feel different. You are actually thinking about the motion of picking up the cup, looking at it as you lift it, and when you go to put it down you have to make sure your wrist is tilted in the right direction. What has happened? While your arm was in a cast the muscles took a nap to recuperate and heal. The muscles didn't realize you expected them to be back on the job so soon and they forgot almost everything, as if they went on summer vacation and now they are expected to go back to school and pay attention. So, go back to school they do. You pay attention to what you are doing, you feel the shape of the mug and the tilt of your wrist until you don't. And when you no longer pay attention, your proprioception is now back to normal and your brain doesn't have to help out anymore.
This happens to our dogs when they get injured too. Hopefully your dog is not into drinking coffee, but running and playing and getting into all kinds of doggie mischief. When our dogs get injured, even if it's a small cut on a paw, they compensate for it by using other parts of their bodies more. Those parts, that aren't used to doing more work than they normally do get tired and sore, and eventually overworked (and massage can help them). When the injury heals sometimes dogs continue to protect it and the dog needs help learn how to use the healed leg/shoulder/hip again. Sometimes wounds heal too quickly and scar tissue develops, or muscles become stiff from under use, and these healed wounds need help to release that tension, develop normal tone, and to be stretched so that the muscles can start to rebuild and regain proprioception.