There are plenty of products that can help minimize the stress HD places on your dog's hip joints. Dasuquin with MSM is an excellent product, and I attended a lecture that recommended using Adequan as a preventative measure up until 14 months. Have the kennel keep him slim and exercised. Stay on low protein food to mitigate his growth and be sure he's getting omega oils and appropriate fatty acids. Do not supplement with calcium and do not allow them to feed a large-breed specific diet without combing through the info carefully to be sure it's appropriate.
Unless your trainer performed x-rays and is a licensed vet or specialist they actually have no grounds to tell you ANYTHING about his hips, let alone declare how 'bad' they may be. See a vet and have an x-ray done to determine if he has HD and if so the extent. It's not a death sentence! Don't worry.