Petra, I'm really sorry to hear this. Blue was diagnosed with mild HD 3 months ago at 9 months old.
This is what I was told: 1. Keep him on the slim side. This is the best thing that can be done for pain management.
2. HD causes Arthritis, there's no way around . That's the reason she'll be stiff in the cold, or after she wakes up. Some exercise daily is a must for as long as possible. It will keep her from getting stiff, which in turns keeps her from hurting.
3. HD is a degenerative condition. It gets worse over time. HOWEVER, mild HD in most bullies can be managed by diet, exercise and anti-inflammatory meds. Once Arthritis sets in, there's no surgery that will get rid of it.
Just want you to know that even though you haven't mentioned Arthritis, that's what's causing the stiffness. Again, the surgery will NOT get rid of the arthritis.
Petra, I'm hoping you're getting a second opinion from an Orthopedic Surgeon. Don't go to a regular vet.
Also, according to OFFA (Orthopedic Foundation for Animals) a not for profit organization, over 60% of bullies have some form of Hip Dysplasia. According to my Orthopedic Surgeon, the number is higher. Most just go undiagnosed because they don't show many symptoms. Just want you to know you're not alone.

to you and BoeBoe
Keep us updated.