Mitt Romney may have a new constituency to worry about: dogs and dog lovers. The group “Dogs Against Romney” held a protest outside the Westminster Kennel Club Dog Show in New York on Tuesday afternoon to bring attention to the story of how 25 years ago, Mr. Romney drove from Boston to Canada on vacation with his dog, Seamus, in a carrier strapped to the roof of the family station wagon — a tale that political commentators and opponents have seized on it as a window into Mr. Romney’s character. About a dozen people stood outside Madison Square Garden with...