In the dog mushing world, 44-year-old Lance Mackey is like Michael Jordan. The sled dog racing veteran returns to the Yukon Quest this year. Katie Orlinsky for NPR hide caption

itoggle caption Katie Orlinsky for NPR

A dog named Sky activates the tug sensor on the FIDO vest. The vest is a piece of wearable technology designed to allow working dogs to perform more tasks and communicate more information. Rob Felt/Courtesy of Georgia Tech hide caption

itoggle caption Rob Felt/Courtesy of Georgia Tech

Laurie McCannon, director of the Northeast Animal Shelter in Salem, Mass., with a dog named Trina. Three-quarters of the dogs adopted from the shelter in 2013 were from out of state. Shannon Mullen for NPR hide caption

itoggle caption Shannon Mullen for NPR

Miami-Dade County's animal shelter takes in more than 28,000 dogs and cats each year. In 2012, the county adopted a resolution that the shelter would become a no-kill facility. But even no-kill shelters can euthanize up to 10 percent of their animals. Greg Allen/NPR hide caption

itoggle caption Greg Allen/NPR

Do you want to go to the park? Mango Doucleff, of San Francisco, responds to her favorite command by perking up her ears and tilting her head. Michaeleen Doucleff/NPR hide caption

itoggle caption Michaeleen Doucleff/NPR

The story of Arthur, a stray who adopted a team of Swedish athletes competing in Ecuador, spread quickly after he refused to be left behind. Krister Goransson/Peak Performance hide caption

itoggle caption Krister Goransson/Peak Performance

David Roberts says the Cyber-Enhanced Working Dog harness will allow humans to monitor dogs' physical and emotional states remotely, such as in search and rescue operations. Becky Kirkland/North Carolina State University hide caption

itoggle caption Becky Kirkland/North Carolina State University

A puppy waits at an adoption event in Miami last year. The city is now considering a ban on the sale of puppies in retail pet stores. Cities and towns in several states have passed similar bans, aimed at cracking down on substandard, large-scale puppy breeders. Wilfredo Lee/AP hide caption

itoggle caption Wilfredo Lee/AP

Boys show off their four-legged friends at a rabies vaccination drive set up by the Serengeti Health Initiative in the Bariadi District of Tanzania. Anna Czupryna/Courtesy of Serengeti Health Initiative hide caption

itoggle caption Anna Czupryna/Courtesy of Serengeti Health Initiative