There is plenty of buzz about Jonathan Unleashed by Meg Rosoff, a beach bag-ready summer read for dog lovers: Marie Claire calls it “A humorous tale of a young New Yorker’s search for happiness, and the two dogs who help him find it." “Buoyant, witty. . . . a frequently thoughtful comedy.”—Publishers Weekly “Rossoff, best known for her award-winning youth books, makes another foray into the adult world here with this sprightly romcom. In reality, though, the age line in her books has never run true. And why should it? Her writings—thoughtful, mutable, and often with love, of one kind or another,…