Marion Warner seeks more than $100,000 -- or her horse -- back from Trebek's Creston Farms, near Santa Barbara, Celebrity Justice reports.
Warner took her horse named Bebe, whose bloodline includes the famous racer Betrand, to Creston in January for breeding purposes.
But in March, she got a call from the farm manager saying the horse had suddenly taken ill, and had been put down by a veterinarian.
Warner's lawsuit claims the description of the horse that was euthanized doesn't match Bebe's and suggests the farm pulled a switch.
Trebek denies the allegations and said he expects the case to be thrown out of court.