Chihuahua owners held their dogs up to see the finish line before the start of a heat at the PETCO Unleashed Chihuahua races in Norwood. At right is Mike Schneider, of Brookline, with Bandit. Next to them is Erica Savage, of Billerica, with Lola. Fifteen races across the country will lead to the championship race in California at PETCO Park in San Diego, Aug. 31. Winners of the regional races get a trip to the finals.