I would guess is something regards a person that is not very smart (raccoon dog) cannot teach someone who is more intelligent (fox).
As fox are considered/represent smart, usually in a deceiving way, it could also mean that a naive person cannot teach anything to a experienced person.
Just my opinion, though. Someone else might have a better answer/explanation.
Isn't it from Japan? A raccoon dog is known for feigning ignorance/sleep (they are amazingly socially adept and organized creatures, but they always give you those blank-stare poker faces like they're up to nothing). Foxes (asocial) are known for not being teachable, doubtful and only ever dabbling, even in English the coy vixen feigning not to know she's desired while knowingly leading them on. Such a penetrating gaze that seems to be looking right through you . . .