Let the dog get rid of the habit of sleeping on his stomach and the problem of splayed feet

Sleeping on your stomach is a dog's nature. This cannot be changed. I don't understand why you want a dog to change it.

Retreat is not because of calcium deficiency. It is because dogs walk on slippery ground for a long time during their development, or are locked in cages. Serious lack of exercise.

Taking the dog outdoors every day can improve the situation.