Dog Diaries: Curse of the Mystery Mutt by James Patterson

Junior is loving his life with the Khatchadorian family. But his idyllic life soon turns to terror when a mysterious individual begins to make trouble in the neighborhood. It starts with a mysterious howling in the night. And when Junior's pooch pals realize their favorite toys are missing, things get serious.

Junior thinks he knows what is happening. He's heard of a mysterious creature called the Howly Wiener that visits town once a year and fills the street with monsters. With only a few days until the Night of the Howly Wiener, can Junior come up with a plan to protect himself and his pooch pals and stop the mischief for good?