Joosse (Snow Day!, 1995, etc.) tells an old story—a new friend muscles out the old, with all the sad consequences—pleasantly enough without plowing any new ground. Nugget is a scruffy mutt. Nell is a young girl. They're thick as thieves: Nugget keeps Nell's toes warm at night; Nell scratches Nugget's favorite spot. They stage magic shows for the stuffed animals and commune with the great outdoors. Things change, though, when Nell adopts a stray kitten that Nugget found. The kitten, named Darling, commands all Nell's attention, raising Nugget's hackles. When Nell scolds Nugget for causing a minor commotion, Nugget slinks away, devastated by the sea change in their relationship, jealousy coursing through his veins. Nell suddenly realizes she has given Nugget the bum's rush, so she goes about setting things right, making Nugget feel special again. There is little distinctive about the plot or in the way it's told, but Truesdell's artwork elevates the pages somewhat- -sprightly and very much in league with the James Stevenson school of pen and watercolor wash. (Picture book. 5-8)