How about same total distance per day but broken up into more walks, thus each one is shorter. Or - just have him walk a little less - if he is tired that last 15 minutes of the walk, make the walk 15 minutes shorter.
He is on Dasuquin with MSM and that seems to be helping for him. I think I've been more of a worrier than I normally would be because he had heartworm when he came to me. His xrays showed some lung damage and his heart was slightly enlarged. His lungs on the xray looked like asthmatic lungs (at least that's how my vet described it to me). So I know there's been at least some damage from heartworm.If he's not starting to fall behind or get gimpy or it's hard to get up afterwards, don't worry too much.
Do you have him on any glucosamine/MSM/chondroitin? Probably not a bad idea to get it going now if you're noticing anything going on in a leg.
I started Cato in agility in 2005 when he was 7. That was when I started training him. Then I started running in trials about 18 mths later when he was almost 9 - he jumped 24". We didn't do a lot of trials because he was too social and wanted to spend time with the ring crew and the photographer and the judge, so I just took him to fun matches so he could have fun - we earned about 8 titles in all.Viv, it's nice to hear that you don't think he's too old yet! I'm hoping he sticks around for a long, long time.
I do the Get on the Ball DVD and I will find my notes from my agility instructor and pm them to you. It might take me a few days to find it. I KNOW it's saved...somewhereAdara, do you have any online resources for core work?