Read the sticky at
http://www.askmehelpdesk.com/dogs/in...tml#post254171 Young Shepherds are notoriously poor eaters. Some owners must resign themselves to having their dogs' ribs show a little. I even had a Lab that was that way. A dog is better off eating the complete and balanced diet a dry dog chow provides and having it ribs show than being tempted with rich food to eat more.
I hope your vet understands Shepherds and didn't prescribe the antibiotics as just looking like he is doing something. Until the ribs show badly, don't take too much action except to feed a decent, dry chow. The sticky makes it plain, if there really is an eating problem, the cause must be found and corrected by treating what is causing it.
Yes, it s tough. We kept friends' Shepherd over the weekend. We only got about 2 cups of adult Pro Plan in her all weekend. She ignored the puppy chow she should be eating even with chicken broth on it. She was bred and hopefully needs to be eating for 6-8. Her mother is the Shepherd mentioned in the sticky.