Artist Laurie Anderson's 2015 "Heart of a Dog" documentary, about love and loss after the death of her rat terrier Lolabelle, is slated to air on HBO April 25, the network announced last week. Anderson, who grew up in Glen Ellyn, last week performed a concert for dogs in New York City to honor Sept. 11 first-responder dogs. Lolabelle died in 2011.