I'm so sorry to hear you're facing this. I've lost a dog to CHF and one to Renal Failure. You've gotten good advice from the others. I just want to send good thoughts to both of you during this difficult time.
Since this thread is sort of buried, you might want to repost asking for experience with supraspinatus tendonopathy, rehab, cell therapy, etc. so more people will see it and someone may know more about it.
I'm glad you got a diagnosis and it's not the dreaded O. I've no experience but I'm sure others will chime in and will be of help in you making your decision about treatment. A friend is doing rehab with her senior greyhound right now for a disc problem in his lower back and it is expensive.
I'm so sorry you got this shocking news. You've gotten good advice from people who've been there. There's some other support online that might be helpful to you: http://blinddogs.net/ - seems to have lots of info and also has a forum. And there's a Yahoo group as well which will likely have lots of resources. http://pets.groups.yahoo.com/group/blinddogs/