I cant say I agree with the vet. I have had dane puppies who love rocks, golden pup who couldnt get enough of them and a German Shepherd who did the same, Galahad OEM is now about 17 weeks and he has never been real bad about it. I think certain pups are and others are not. Mind you, you really want to try and keep him away from it, start early with the command "leave it" and excange the rock for a treat, and praise lots. Many a dog has had to have surgery to remove rocks. So try and be on top of it and break him from it as soon as you can.
Do you have any pics of your baby, it would be so much fun to see him and please please let us know more about him.
Marit
am attaching a pic of Galahad when he was about 10 weeks