Major sire Unbridled, who underwent two operations at Hagyard-Davidson-McGee veterinary clinic near Lexington in September, was euthanized Oct. 18 at the clinic after a severe bout of colic. The 14-year-old stallion was treated at the Hancock family's Claiborne Farm near Paris, Ky., then sent to Hagyard-Davidson-McGee, where it was determined that the symptoms rendered his condition inoperable. He was put down at 6:00 p.m.Unbridled's original trouble started with the removal of more three feet of colon on Sept. 21. He suffered a setback in his recovery five days later and a second operation was performed. He arrived back at Claiborne Oct. 8.Champion 3-year-old male in 1990, Unbridled (Fappiano--Gana Facil, by Le Fabuleux) sired 24 stakes winners and is represented this year by two-time grade I winner Exogenous and grade II winner Broken Vow. Three-year-old Exogenous is one of several of Unbridled's offspring ready to contest a Breeders' Cup race Oct. 27 at Belmont Park. Unbridled won the 1990 Breeders' Cup Classic (gr. I) at Belmont and took that year's Kentucky Derby (gr. I).Unbridled, who began his stallion career at Graham J. Beck's Gainesway Farm, stood at Claiborne since the 1997 breeding season. He ranks ninth on the 2001 leading sires list.