Dogs from the nimble herding breed have won the Westminster Kennel Club's agility competition in each of its two years. Some 330 dogs ranging from petite Pomeranians to a giant schnauzer were signed up to scramble through the timed course of jumps, tunnels, ramps and more. The animals compete in height classes, but unlike many other agility trials, Westminster has the class winners run off to crown one top dog. While he didn't have a good day, owner Debbie Lazaro of Howell, New Jersey, feels "a mixed-breed definitely could win." [...] no matter the genes, any dog — or handler — can make a mistake. Rickie Roo, a rat terrier, has to trust owner Deborah Davidson Harpur to help her navigate the agility course: