I have a beautiful Mastiff x (sam in my sig picture) and he was diagnosed with advanced hip dysplasia when he was 18months old. It was devestating at the time because we were told he would have a shorter than normal life and on medication for most of that as well.
There are treatments available. I use a combination of Sasha Blend treats and Metacam anti inflammatory (more so in winter when he gets stiff and sore). They also have an experienmental surgery running at the Kur-ring-Gai vet hospital where they use stem cells from fat and transplant them into the sockets to help regenerate the area. It hasnt had a surgery yet that hasnt shown some sucess, however the minimum rate is around 12%. I imagine it would be quite expensive however.
As well, we were told to exercise him using water based activities or light walking. Try not to throw balls and toys as much as it jar's the joints.
It is a horrible thing to hear, especially in such a young pup but there is hope. And your dog still has some growing to do so I would ask for a repeat xray when they are closer to maturity to determine the extent again.
HTH and all the best