To help your dog after she gives birth, feed her puppy food that's high in protein and calcium until the puppies are weaned so she can produce plenty of milk.
Isolating and stretching these muscles can cause adhesions to break up, resulting in a minor soreness similar to what you would feel after a good workout.
It takes a few weeks to a month or more to recover physically after a miscarriage. Your recovery will depend on how far along you were into the pregnancy.