Assuming a dog was trained to run along side his Marathon running owner. Could the average healthy young-ish dog do it? given a chance to properly hydrate.
Obviously some dogs couldn’t. My bulldog never could run 150 yds without passing out but I am talking about a healthy border-collie Jack Russell mutt.
Sled dogs can do 40 miles in under 3 hours, so I’m guessing they could beat any human record over a distance of 26 miles.
:smack: How could I not think about Sled dogs :smack: Of course they are specifically trained for that task.
Wolves and humans both use cursorial hunting as a strategy to catch prey, so it’s not surprising that our best friend (same species as the wolf) is also a long distance runner.
Not on a hot day.
I now have an idea in my head to loose dozens of Border Collies in to a giant pack of marathoners and watch them herd the runners.
Actual sled dogs–that is, dogs that pull sleds, not just husky breeds–get a lot of conditioning and exercize. If your husky has been sitting around the house all day he’s going to struggle to run a marathon just like you would.
Also note that sledding takes place in cold temps-a typical 60-70 degree marathon day could lead to the canines overheating, unless they can get regular water dousings/drinks along the route.
You happened to pick one of the few species that can run anywhere that distance in that amount of time. Humans and dogs have unusually good endurance running ability in the animal kingdom. That is one of many reasons why dogs are good matches for humans.
I believe that I read here that dogs and man are the only two species that can run a marathon that quickly. I welcome anyone to correct me on a list of other candidates. I don’t think horses can beat champion marathon runners or sled dogs in a marathon for example just because they can’t keep pace at decent speed for that long. Can dolphins or whales swim a marathon that fast?
I found an older thread on it with good info.
http://boards.straightdope.com/sdmb/archive/index.php/t-539085.html
Just like humans, a dog needs to train. The distance is not a problem. It’s almost a given that the dog would train with a human running partner. The proof is that dog have run marathons around the USA. They used to run the old Detroit Marathon when it was the Victor Glance Marathon on Belle Isle in Detroit. With the international border crossing in the modern course, it’s more unlikely except for a possible assist dog for a blind runner. They usually use a rope connected to another runner though.
If the dog is not trained and motivated with a partner, it may well just quit. That’s what dogs do. And they have their own types of injuries.
Watch out for those Kenyan dogs. They’re the fastest! 
That link of horse vs man over 22 miles is with a rider, and its a very close thing, first time a runner won was in 2004.
I suspect with the rider out of the equation, it would be advantage horsie.
Edit: Doh, helps to read a bit more of the thread.
Otara
Would it though? The rider has the advantage of knowing what the goal is and managing the horses energy to achieve the goal.
Of course, if we’re going to be expanding the definition of “run”, then almost all birds could kick any land-bound critter’s butt.
Would a horse need to train the way a human or dog would, or would a well-fed healthy horse that got regular exercise be good to go?
The Pronghorn is probably well ahead of both. From this link:
Not on the streets of Boston, they can’t. 
A horse would need aerobic conditioning specific to trying to build stamina, just as a human or dog would. For many horses, regular exercise is an hour or less of work including walk breaks, and 3 hours of sustained trot would be ugly at best.
Someone in that other thread compared the Vermont 100-miler - mostly run on gravel roads - to the Tevis Cup, which is run in rough terrain in the Sierras, so I did a different comparison. If you go to the Vermont Endurance Ride website and scroll down, it states that the ride record is 11.5 h and the runner record is 14 h. At least for that subset of presumably well-conditioned horses and runners, the best ridden horse still outpaced the best runner over 100 miles on the same trail.
Is that 11.5 hours of continuous running, or does the clock stop while the horses are being rested?
Because I do not believe for one second that a horse can run non-stop for 11 hours. And if the horse is stopping for rests then of course it is going to win, it is much faster over short distances.
And to get back the OP, yeah a dog will handle a marathon easily. While I’ve never taken a dog on a marathon, I’ve taken my dogs and many of my friends’ dogs on 2 hour runs many times. They have no problem at all keeping up. Even dogs that have had no training at all will handle a 20km run without breaking a sweat. These are animals that are built for endurance, and the ~10 km/hr pace of the typical marathon runner isn’t going to faze them in the slightest.
However you do have to understand that dogs have real difficulty coping with high temperatures. If the temperature is above 30oC do not even think about running a dog unless you know it well, you can read the signs of distress and you are prepared to stop at least every 20 minutes for water. Above 25oC be very careful running for more than half an hour at a time. Once you now your dog, then the risk of doing any damage is minimal at lower temps. Most dogs will simply stop if they are overheating, and so long as you do not force them to run after that point they are pretty safe. A small number of dogs unfortunately will not stop, and will run themselves to death very easily. However even with these dogs you can get around the problem by stopping for a minute every 15 minutes or so if there is any doubt. If it is overheating, even the most boneheaded dog will refuse to start running again once it stops, and so long as the temperature is below 25oC you won’t do any damage in 15 minutes.
Frankly I would be more worried about damaging the animal’s paws on a marathon than about the animal not keeping pace. Most marathons are run on asphalt and concrete, and those surfaces are hell on a dog’s pads when they are running.