Meet Jellybean, a 9-pound chihuahua-dachshund mix. She's run seven marathons and two ultras with her owner, and these are a few of their favorite races.

While you’ve been mapping out training schedules, your dog has been napping in the sun. And forget those pricey Maurten gels; Bud’s been chomping the same dried food for every meal. And yet, they’ll ...