LONG BEACH, Calif.—As he sauntered along the red carpet, Filbert squirmed in his tuxedo and high hat. Bentley, who has his own social-media account, drooled nonstop. Harley, a skateboard and surfing buff, sniffed the air.

Their deportment may be wanting, but these contestants in an annual beauty contest here still charmed the crowd. They were among the top dogs in this southern California city's 10th annual Bulldog Beauty Contest. The event last month attracted 200 of the squat, squishy-faced and much-loved canines from as...