In their third chapter-book outing, doggy best friends “Down Girl” and “Sit” must contend again with their misguided masters and the annoying cat, “Here Kitty Kitty,” who lives close by. The running joke is that the down-to-earth dog telling the story fully believes her name is “Down Girl” because she hears it so often. The gag may become a bit hackneyed by the end, but it’s hard not to appreciate the funny miscommunications between loving pets and confused owners, all told with a limited vocabulary for children just making the transition from early readers. In one hilarious chapter, an obedience lesson in the park rivals Abbott and Costello’s famous “Who’s On First” routine, since Sit, Down Girl and Hush are all in attendance, and those same commands are being put to heavy use by owners who all seem to have forgotten their own pets’ names. Reed’s black-and-white illustrations appear on almost every page, extending the three or four paragraphs of text. Young readers will “stay” for the end of this one. (Fiction. 6-10)