At times, it was hard to tell who was taking who for a walk as America’s new presidential puppy was finally presented to the media.For a moment, the economic crisis, the North Korean nuclear standoff and Somali pirates could all be forgotten. On the south lawn of the White House, the moment belonged to Portuguese Water Dog Bo, the pooch promised by Barack Obama to his daughters. A gift from Senator Edward Kennedy, the highly energetic Bo is just the latest in a long line of presidential pets. Bill Clinton formed a bond with Buddy the chocolate labrador and was devastated after leaving office when his four-legged friend was run over by a car. And then there was President George W. Bush and his wife Laura’s beloved Barney, a Scottish Terrier who featured in several specially-made films.