KENNETT SQUARE, Pa. -- An Erie Zoo polar bear operated on by the surgeon for Kentucky Derby winner Barbaro died just hours after surgery yesterday.

Dr. Dean Richardson operated on Alcor, a 750-pound bear with two badly broken bones just above his right paw, yesterday afternoon and stabilized the wrist during surgery with locking plates.

The bear had been stable and was waking from anesthesia when he died, the University of Pennsylvania's George D. Widener Hospital said in a statement last night.

Alcor will be returned to the hospital to undergo a post-mortem.

Zoo officials do not know how Alcor broke his leg, but they suspect he did it Aug. 11 while playing with his brother Mizar, another 7-year-old bear who has been at the zoo since 2001.

Barbaro broke three bones above and below his right rear ankle at the start of the Preakness in May. The horse is recovering from surgery.