My dog Duke has been diagnosed with this. He is a yellow Lab who will turn 13 in November. Apparently it is fairly common in larger breeds, particulary labs. There is a surgery for it, but of course there are risks. I love my Duker and had a knee surgery done in 2005 at the cost of $3,000, so money, although a concern is not the ultimate issue. From what I have researched he is not in the end stages, more like the beginning. Right now I have added 3 air conditioners to my house to keep it cool and the humidity low which is a problem. I really hate to subject the poor guy to an operation. I know labs live 12-14 years on average with a few going a little longer. I know one lady who's lab went almost 18 years, but he was blind and deaf and truthfully I think it is selfish to keep a dog alive for our own benefit when the quality of life is just not there. Just my opinion.
Duke is fine most of the time. He just gets excited of course (mild) for breakfast and dinner and can get quite agitated and overly excited when company comes over. I have read sedatives can calm that behavior a bit, but of course we don't always know when someone will stop by.
My inclination right now is to keep him cool during the summer and take things as they come for a while. It pains me to know he is on his senior days, but I also understand it is inevitable.
I want to do the right thing and nobody can probably give me the answer right or wrong, but I want to ask opinions nonetheless.
From what I have read people who have opted for surgery have found the dogs will run and play and swim again. Duke will play frisbee but really is past his days of running and swimming so I don't see that as a potential positive of opting for the surgery.