Andrew Lost On the Dog — J.C. Greenburg

ANDREW DUBBLE CAN INVENT ALMOST ANYTHING!
With the help of his super-smart pocket robot, Thudd, Andrew builds an amazing shrinking machine. When it accidentally shrinks Thudd, Andrew, and his cousin Judy down to specks, they find themselves outside a cave of sticky goo. Around the cave is a forest of fur, full of blood-sucking monsters. Where are they? They're on the nose of the neighbor's dog! And they've only got eight hours to get back to normal size. Can they do it? Or will they be lost on the dog for good?