Ok, this is not an issue for me yet, but it's coming and I just wondered how other people have dealt with the same situation...
I have an older dog (she'll be 13 at the end of November) - she's a kelpie - a very active, energetic breed.
I also have a 3 year old border collie.
I'm beginning to notice that Kira, the older one, is not as energetic as she once was on our walks and she's a bit stiff and sore in the evenings (know the feeling anyone??). Don't get me wrong, she'd never admit she can't do it anymore, she'd keep going till she drops, given the chance! (That's a kelpie for you

)
So at some point in the not so distant future, I'm going to have to address the fact that I'll need to take Finn out on another walk after I've walked them both so that he gets enough exercise.
Problem is, the only time I ever separate them is when one of them has to go to the vet. She's going to be devastated to be left behind

.
So, I'm assuming this isn't a new problem. Can anyone tell me how they've handled it?