Cat thieves are not going to be brazen enough to carry dozens in an open pickup... I was involved in a case once where I caught a guy stealing my neighbor's catalytic converter.  Called the police and gave them the license # of the car.  They did their voodoo and found the cat - and caught the thief red handed at the junkyard selling a cat he stole from another SUV. Read the laws on citizen's arrest very carefully.  I don't believe you can citizen's arrest for a misdemeanor.   Felony theft is $500 or more.  Even though it can cost thousands to buy a new cat the valuation of an item stolen from a private individual is based upon the *used* value of that item.  That is, whatever the junkyard will pay for it.  About $50.    (If the cat is stolen from a commercial vehicle then the valuation is based upon the cost to replace with a new item) Citizen's arrest for a misdemeanor is likely going to backfire, hard.  And doing violence upon them is equally going to backfire. Cat clamp, straight pipe, park in a garage, engrave your vin on the cat with "If offered for sale please call the police" etc.   Sucks, but there's not much you can do without getting into trouble yourself.