LOS ANGELES — People aren't the only ones suffering from a seemingly endless winter of bone-rattling cold, record-busting snow and ice-slick sidewalks. Pooches' paws feel the pain, too.While millions of residents from the Rocky Mountains to the East Coast shovel snow deep into the season and hunker down awaiting relief, their dogs are either missing out on walks or left vulnerable to injury with each salt-coated step.