A word from the designer:
The inspiration for this puzzle comes from the "Horse" puzzle, also available in the Mind Master Collection.
While the horse puzzle was derived from a puzzle made with real horseshoes, the difficulty of the W-U puzzle is ramped up considerably in comparison to the original.
The hint is "Hoof".
Puzzle Master makes a large assortment of disentanglement puzzles, brain teasers, jigsaws, puzzle rings, trick locks, boomerangs, chess sets, etc. This Canadian company specializes in taking traditional puzzle designs and adding their own unique touch.