Metropolitan Transit Authority (MTA) Police Officer Keith Flood trains with his K-9 partner Doc, a German Shepherd, inside the “warehouse room” at the new MTA Police Department Canine Training Center in Stormville, New York, U.S., June 6, 2016. (Photo by Mike Segar/Reuters)

A Pomeranian dog is seen during an international dog exhibition in Kannot, central Israel May 21, 2016. Some 850 purebred dogs from about 200 mini breeds participated in the exhibition. (Photo by Amir Cohen/Reuters)

Stray dogs run at dog sanctuary Territorio de Zaguates or “Land of the Strays” in Carrizal de Alajuela, Costa Rica, April 20, 2016. In a lush, sprawling corner of Costa Rica, hundreds of dogs roam freely on a hillside – among the luckiest strays on earth. Fed, groomed and cared for by vets, more than 750 dogs rescued from the streets of Costa Rica inhabit Territorio de Zaguates or “Land of the Strays”, a pooch paradise. (Photo by Juan Carlos Ulate/Reuters)

A dog snuggles up to a potential owner on the opening day of Dog Cafe, a coffee shop where people can adopt shelter dogs in Los Angeles, California, United States, April 7, 2016. (Photo by Lucy Nicholson/Reuters)

Labrador puppies “Hoey” (L) and “Hatton”, named in honor of September 11, 2001 attack victims Patrick Hoey and Lenny Hatton who died in the World Trade Center, are pictured on the grounds of the Pentagon near Washington, June 28, 2011. (Photo by Jason Reed/Reuters)

English Setters rest during the second day of the Crufts Dog Show in Birmingham, Britain March 11, 2016. (Photo by Darren Staples/Reuters)

Owner Elizabeth Wilson groomes her Chinese Crested and Coton De Tulear dogs during the annual Crufts Dog Show at the NEC Arena in Birmingham, Britain, March 10, 2016. The world's largest dog show will be held from March 10 to 13 with 22,000 dogs competing for the world class title of Crufts Best In Show. (Photo by Nigel Roddis/EPA)

Musher Justin Savidis' dogs wait in the truck before the restart of the Iditarod Trail Sled Dog Race in Willow, Alaska March 6, 2016. Mushers and dog sled teams from around the world embark on the first leg of Alaska's grueling Iditarod Trail Sled Dog Race, starting a nearly 1,000-mile (1,609 km) journey through the state's unforgiving wilderness. (Photo by Nathaniel Wilder/Reuters)