Minstrel has been on Yumove Senior since he turned 9, 3 months ago, previous to that he was on Yumove + I put him on Yumove because he did not seem comfortable when out on walks and was stiff when getting up after laying down for a while.
Vet was quiet happy for me to put him on them (Minstrel, not the vet
)when I explained the situation The Yumove + certainly helped, but as you say there are so many versions and on
Amazon it said the Senior version was for dogs over 9 years, I thought it appropriate to change, but I think I may well put him back on the + version when I have used all the Senior ones up. (can't explain it, but I think he was better on +)
Now Yumove have bought out the new Yumove Joint Care + 'for older dogs' and it's all getting a bit confusing.
Hope you find something out of the above that makes sense