Have you got dog insurance Thierry? Because this is about to get verrrrrry expensive.
I have 2 labs - litter brother and sister. Parents both fully checked and scored etc, but one of mine (the dog) got the genetic short straw from somewhere and has elbow dysplasia and patella problems. Poor thing only has one good leg.
I noticed he was unsound at 12 weeks. It took a further 3 months to get a vet to agree.
These are some of the things we've done/continue to do:
Cod liver oil/chondroitin/glucosamine every day. We give him the human ones, wrapped in salami, a couple every evening.
An operation. Done at Willows in Solihull it was mahoosively expensive (8 years ago), but made a massive difference.
Metacam - a veterinary anti-inflammatory. I try not to use it too often - only when he is very stiff.
Short walks and often.
Swimming is much better for him than walking.
A super comfy bed - lots of padding - so that he's not putting pressure on it whilst he's asleep (which being 9 he thinks should be about 20 hours a day, preferably with my lap as a pillow).
I hate seeing him limp and it is much worse in damp weather, but he is a happy thing. Please make sure you get him neutered, I am sure you will, but it would be terrible for puppies to have a father that was unsound.
All in all, he's still your lovely dog. I wouldn't swap mine for all the tea in china.