I have a rescue newfie who's thought to be between 5 and 8 years old. She has severe hip dysplasia in both hips.
My situation is different from yours in that my dog has had a hard life and has been through numerous health problems. At present she is recovering from malnutrition and has very little muscle mass. You can read her history if you read the postings about my "picky eater." Still, you may be interested in our experience.
When I got her 4 months ago, the rescue folk told me that she wasn't able to sit, but that she could stand up and lie down. When she's standing, her legs trimble. The rescue folk told me that they didn't recommend hip replacement for her, but suggested instead that I concentrate on helping her gain weight and build up her muscles with exercise. At that time she was already receiving monthly injections of Adequan and was taking a white pill (can't think what's it's called). They gave me a supply of the medication. Two months ago when I took her in to the vet for her shot, I asked the vet whether I should get more of the white pills. She suggested changing to Cosequin-DS which is more compatible with the Adequan. She said to give Savannah 1 or 2 capsules a day. Initially, I gave her one capsule a day and I didn't see much difference. Once I started giving her two capsules a day, I did see differences. She has now been able to get up into the back seat of my car without help three times and she sits. I don't ask her to. I use the command "Down" and accept whatever she chooses to do - sit or lie down. More and more often she sits. In addition, she sits on her own.
Before I changed to the Cosequin-DS, I was feeding her the IAMS in the green bag with the glucosamine. I don't think it helped much. I now cook for her because getting her to eat and gain weight is so important to her regaining her health.
It may be premature for you to begin giving her the Cosequin-DS. It is expensive. Still, I'd suggest talking with your vet, if for no other reason than to find out what an appropriate dosage of glucosamine/condroitin would be for your dog.
Melani