Retractable claws are a feature most commonly found within the cat (Felidae) family of animals, and also in some members of the Viverridae family such as genets and civets.
Foxes, however, are members of the dog (Canidae) family. Because of this, foxes cannot retract their claws, with the exception of one particular species: the gray fox. Gray foxes have partially retractable claws, capable of lifting off the ground when running. This means that gray fox tracks typically do not contain visible claw marks, as is found in other fox tracks.