On the Dog: Andrew Lost #1

When Andrew's latest invention, the Atom Sucker, goes haywire, Andrew and Judy are shrunk down to microscopic level! Andrew and Judy find themselves lost on their neighbor's dog, where they encounter everything from colossal fleas to crab-like eyelash mites. Now they have to find their way back to the Atom Sucker and get unshrunk before it's too late!