During a conversation with Shelly de Killer via a transceiver, Shoe meowed just as the assassin "hung-up". This allowed Wright to figure out that de Killer was holding Maya Fey in Engarde's Mansion, and attempt a rescue effort. Unfortunately, de Killer had already moved on by the time they arrived.
The cat's English and Japanese names ("Shoe" and "Shū", respectively) come from the given name of Shu Takumi; original creator of the Ace Attorney series.
His French name, "Pantoufle", comes from the French word for a slipper. This appears to be a reasonably direct translation of the English name without the added reference to Takumi. The same naming method was also used for the German, Spanish, and Italian localizations ("schuh" and "zapato" both mean "shoe", while "scarpetta" is an Italian word for either a child's shoe or an elegant ladies shoe).