Running with the Big Dogs

I hardly ever take my dogs running with me. I have two big dogs, Rusty and Penny, and they love to run. I feel guilty about not taking them with me when I go out. (And they make it clear to me that they're disappointed in me.)
But taking them with me is a drag. They want to stop and sniff this and that, mark here and there, take a dump, leap at a cat, yank on the leash and pull me along, or drag me backwards.
Anyway, I took them on a run last week and went 3 miles in 45 minutes. It was a little tedious and a good example of why I don't run with them. But I felt like they had done all right and I should take them out more often. Maybe that was because I had just done a treadmill run the day before, and anything is better than that.
So I took my dogs out again last night. I didn't feel like we were doing anything different. After we were running for a while, Penny, the older and heavier dog, started to drag and indicate that she was tired. I thought I had better start thinking about getting home. For the first time I looked at my Garmin to see what my mileage was, and we had gone 3.5 miles in 33 minutes!
By the time we got home, we had gone 4.5 miles in 45 minutes! We went 50% farther in the same amount of time! These dogs could do OK if I ran with them more often. I was proud of them.