I have run with my dog (and GF's dogs) just about every run since I got my first dog. My first dog (with me 2000-2015) was a husky/border collie mix, and we ran up to around 120 mpw on trails and mountains and in orienteering meets in the woods, with some limited road at times (on the way to the trails), and cross country skied in the winter. She was really energetic until she was about 3. After that, she would often drag on the familiar runs from boredom, but would be a happy summit seeking dog in the mountains or a new trail. Her last big outing was when she was 15, when she did her last mountain, a 8-10 mile, 3000+ ft of climb trip, hiking slowly with some energetic puppies.
My current dog is a Belgian Tervuren, a big 85-90 lb furry boy. He's done up to 90 mpw on trails, but I should probably reduce his mileage a bit. I can tell his energy levels by how much he wants to play disc (toss and fetch - I usually carry a disc if we are running by fields). He doesn't let go of the disc for the next throw if he's tired. I keep paces slow for him when it's warm. I did do a 10 mile training run in 60 minutes with him once in the winter on snow and similar paced 14-mile skis, but I wouldn't do that in the summer. He too big and doesn't like continuous paces of faster than about 7:00. He's a great bear dog. Last summer he chased off a half dozen bears during our runs.
I'm lucky to live in Alaska. All my runs are close to water for the dogs to cool off and drink in, except higher in the mountains, where it doesn't get hot. When I'm in CA or New England, I have water locations in mind when I decide where to run.