What is a good breed of dog to run with?

In my opinion the dog for you would come from the Sporting group. These are the athletes of the dog world. There are several smooth-coated breeds in this group, and as these dogs are more biddable you should have better luck training them to run alongside you off-leash. I would not trust a hound or terrier off-leash; they can get side-tracked so easily and they are bred to be independent thinkers.

Some breeds that might suit you: the German Shorthaired Pointer, the Pointer, and the Vizsla are all smooth coated. I've personally worked with all of these dog breeds (and I was raised with GSPs) and I think any one of them would be your best bet. Don't go with Weimaraners, though; the vast majority of the ones I've met have been horribly neurotic animals. I mean I suppose there's always an exception, but...I haven't met it yet. Beyond that, somewhat longer-coated but still manageable dogs would include the Brittany, the Boykin Spaniel, and the English Springer Spaniel. All very good dogs (and I currently have Brittanies...not that I'm partial!). If you like the coarse coat of the Border Terrier, you might also like the German Wirehaired Pointer, the Wirehaired Pointing Griffon, or the Spinone Italiano.

All in all, most any dog will probably be a good running companion, but it will take consistent training to ensure they do well off-leash. I recommend adopting an adult dog from a purebred rescue first, as an adult dog will be ready to run, while puppies usually need to wait until at least 1 year of age before engaging in heavy running. And then of course you could always just check out your local shelter and find a nice small to medium-sized dog with a desirable coat type and energy level. Good luck! :)

I would not trust any terrier off the lead. Even if they are trained, you are still taking a chance that it could see an animal or something and bolt. Any dog really could do that.

My aunt has a Staffie, yes I know it's still a terrier, but she has a ton of energy and runs just about as much as you. She's never off the leash though.

You can go to a shelter and look at the puppies and dogs they have. Maybe there's a mutt there that has short hair, fairly small and needs a good home. I would say a herding dog mix, but they cna have long hair.

My pit bulls love to run, so you can maybe try them???

That is some distance so you are really looking for a dog suited for endurance rather than short spurts of energy and not so much a small dog for that sort of distance more a medium build or even a "sled dog" like a husky but that would not be suited for if it was too hot.

Dogs that could cope with that sort of thing, if built up to the final distance gradually, would be a greyhound, retriever or labrador or a good old Heinz 57 mixed breed, which are less susceptible to inherited problems. I'd be wary of a border collie for long distances like that as they can be prone to hip dysplasia, as can German Shepherds also avoid any breed with a foreshortened muzzle like the bulldog as they would have breathing problems.

Be sure to take plenty of water for your dog and keep an eye on their feet too. Build up the distance gradually and don't ask too much of your dog too soon. Remember a dog will not show it is ailing as humans do, they want to appear strong and will run themselves to death rather than lie down and rest for a while so you have to think for them and show consideration for their ability to keep up with your long legs and feet protected by trainers, and sips from high energy drinks bottle. A dog cannot tell you when it has had enough, in fact it will keep going. Its to do with their survival instinct and not showing vulnerability or weakness.

In my opinion, shorter distances good idea, long distance to be approached with great care and understanding.

Collie, Border Collie, retired Greyhound, any breed of Terrier (minus bostons and yorkies), Pit Bull, Boxer, Borzoi, Saluki, German Shepard, Vizla, Rhodesian Ridgeback, most breeds of hounds ( but not bassets or doxies) Lab, Golden Retriever, Standard Poodle, and if you live in the proper climate for it a Malamute or Husky. All of these dogs would love to run for a few hours a day, so pick a favorite and research it's personality to make sure it's a good fit in other aspects - then enjoy your new friend and running partner. Oh, and if you rescue an adult dog, you have an immediate running partner instead of having to wait for a puppy to grow up. Plus, rescues can tell you other stuff/ quirks of the dogs' personality, so no surprises! Good luck!

Research German Shorthaired Pointers. They have an incredible amount of energy/ stamina, and while I normally don't recommend them, one might be the perfect dog for you. They LIVE to run and are built for it. They're also devoted, sweet-natured dogs that happen to be intensely tuned-in to their owners and *love* to please (so training is extremely easy). They just need to be kept on-leash or in a fenced area because if they see a squirrel or bird they just go. They're really talented at escaping enclosed areas, but as long as you supervise the dog things should be fine.

They do tend to shed a fair amount, but it's manageable as long as you brush them with a curry brush regularly. I'd also suggest a Dalmation, but they shed a ton lol.

ETA: A lot of people are suggesting sighthounds (greyhounds, whippets, etc), and while they're wonderful dogs and are great runners, they're not the best for going long distances. They're great sprinters, but don't generally like to go long distances. Dogs like GSPs and Dalmations do, though.

Also, with Border Collies they *do* have a ton of energy, but simply running with them won't cut it. They also need a "job"--that is, some kind of training or enrichment work throughout the day. Just running with it won't help out with the *mental* exercise they need.

My neihbor has a Rodesian Ridgeback named King, he uses the car to fufill King's exercise needs he runs the dog 20 miles at 8-10 mph on saturdays. The dog is short haired, doesnt shed and also goes lion hunting with my neighbor.

Terriers is a good choice. Although I would also remind that you should also consider a dog's grooming maintenance, diet and bonding time that it needs to keep it happy and healthy. I would recommend that you watch my 4 minute dog choosing video at http://www.youtube.com/watch?v=6pxui6GMCfo to help you in the decision making of finding the right dog breed for you that fits your lifestyle and preference. good luck with the new dog!

A Border Collie is the smartest of all dogs and needs to run and get exercise.

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Grey hounds are the best know running dogs based amazing running ability . They can run great distances, and I think that since you run over 20 miles, this is good