Thank you both for taking the time to reply.
Hello again Halfstep

Thanks for the link, very interesting reading, even if I did have to read it 3 times, it has given me a much better understanding of the mechanics of the hock.
I have this morning studied Barney's x-rays with his vet in depth. Although she said that one of the possible options was Tildren, she personally didnt rate it but would be happy to do this if I wanted. IRAP wasnt mentioned, but I will ask her about this.
After a long discussion we have decided that the only hope of making him more comfortable, and in the hope of slowing down the degeneration of the Tarso Crural joint which has mild changes atm, is to medicate with steroids and Adequan. Three other horses on the yard have had this treatment, one of which has worked.
The lower joints have almost fused and in time when they completely fuse, he will be much more comfortable.
Lots of turnout is recommended and she has agreed that as B is so obviously thrilled to go out on a ride, gentle exercise at his own pace would be ok.
As long as he is happy and painfree, all I want is for him to have as many enjoyable experiences in whatever time he has left. He is in no way depressed and just wants to play and groom his pals for most of the day. He is still thundering around his field and putting in some spectacular bucks.
All being well, he is going into clinic next weekend and will have both hocks x-rayed and then medicated. Fingers crossed that this treament will work for my little Bear.