Try visiting the dog park in off peak hours and practice gaining focus from your dog before you allow him to run off and play. (barkbusters.com)
To reduce the risk of the above and many other health problems, buy only from reputable German Shepherd breeders (visit dog breeders to learn how to identify responsible dog breeders). (puppy-training-solutions.com)
When asked to take a case such as this I prefer to visit the dog in his home and meet any people that play an important part of his daily life. (k9magazine.com)