My first thought would be to find out whether your dog actually lacks energy or is just a laid back personality. If this is simply your dog’s natural temperament there is little you can do to make him more super-charged. In fact, I’d be willing to bet that there are a few owners of 13 month old GSDs who wish their dogs were a little calmer!
A vet should really check your dog over, especially if you are going to be doing active obedience work, to make sure that the heart is fine and that there are no other obvious reasons for your dog’s quiet demeanour. If everything is fine health-wise then it would be worth feeding a performance food or a puppy food for another few months as GSDs may not be completely physically mature until 15-18 months. Both foods have higher levels of protein and other nutrients that help fuel physical activity and ensure a quick recovery following exertion.
By Libby Sheridan (Hills Pet Nutrition) (Professional Advisor)