Terry Pratchett's The Amazing Maurice and his Educated Rodents (HarperCollins, 2001) is full of talking animals. So, does it belong in the Teen section of the library (YA) or in the Juvenile section of the library? I took the book home to see.
Maurice is a cat. The boy is a piper and the rodents are sentient mice. Maurice comes up with a scam to end all scams. He send the rats into a village to carry on shamelessly. Then the boy offers to pipe the rats out of the village - for a fee. The rats willingly stream out of the village after the boy and they all move onto to another town.
When they come to the village of Bad Blintz, the group find a weird and creepy situation. Rat catchers seem to rule the village but there are no native rats in sight. Worse yet, the mayor's daughter, Malicia, has decided to stick to the boy, and to Maurice, like glue.
There is "Evil" in the tunnels under Bad Blintz, and greed, and revenge. And being a rat who can think is an existential curse at times. A battle to the death, poison and traps, tricks and betrayal, and acts of extreme kindness, all take place in the dark and hidden places.
Younger readers - ages 10 and up - will enjoy the novel. But the angst and the humor will be best appreciated by teens and adults.