Buying and Selling: Buying and Selling the Skin of a Fox or Similar Animal
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 2068
If a fox or similar animal is not slaughtered according to Islamic law or dies by itself, then based on obligatory precaution, buying and selling its skin is not permitted; however, if it is doubtful [as to how the animal died], there is no problem.
-Ayatullah Sistani, Practical Laws of Islam, Buying and Selling