
My first 2 dogs both had this condition with the worst score possible, also bought from what I thought was a good breeder when I was living in NZ. Both my boys were lame within a month of me having them, they had a good diet and little off property exercise as they were waiting to be clear from their vaccinations.
It is not a recommended test for the breed (Chow Chow) and my breeder tested his bitch after I contacted him and she had the worst score possible as well, we assumed she exhibited no lameness as being a bitch she was smaller and lighter than a dog would be.
Both my boys had arthroscopic surgery at 5 months and had to have 6 weeks of cage rest thereafter, not much fun for puppies and very stressful for me. After they were allowed to be exercised they went for very short walks which left them lame every time, they were lame on and off until around the age of 2 when I assume they had stopped growing.
After that they had no noticeable problems and were happy and pain free. I lost my Balto to stomach cancer when he was 6 but I still have Baloo now 11, he will not see another winter but only needed daily pain meds when he turned 10, he has had a happy life and I am happy that I made the right decision in giving them the surgery.
My newest Chow I got from an ABS breeder, well respected and also a judge, I asked about elbow scoring and he seemed surprised, it is not a recommended test in this country either. I had thought it was just bad luck with my first boys but Thor also started to go lame when he turned 3 years and x-rays confirm arthritic changes in his elbows and shoulders. I had been very cautious in his exercise as I was so scared of it happening again. He is too old to have the same surgery and luckily he does not seem to be as severe as my other 2.
In my experience just because a test is not recommended doesn't mean it shouldn't be done, when searching on google for information I came across many posts from people having the same problem with their Chows and I wonder if breeders are putting their heads in the sand regarding this disease as it will disrupt their breeding programs too much.
I hope my experience with this horrific disease will help you decide what path is best for you and your dog, surgery is tough but worth it in the end provided it is done before the age of 1, the earlier the better. Others have managed this disease without surgery, mastifflover on this forum is one, I hope she sees your post to give you her experience.
Good luck to your boy.