The performer who fell ill at the opening ceremonies of the Alltech FEI World Equestrian Games Saturday night was world-renowned equestrian Eitan Beth-Halachmy.
His condition on Sunday afternoon was listed as critical, according to University of Kentucky Chandler Hospital.
A family spokesperson said he is in intensive care and that more information should be available for fans later on the Web site Caringbridge.org.
Known for his Cowboy Dressage, Beth-Halachmy slumped off his horse, Santa Fe Renegade, as they left the outdoor arena Saturday night. Medical personnel performed CPR as he lay on the ground.
The spokesperson said the horse is unhurt.
In addition to the opening ceremonies, Beth-Halachmy had been scheduled to teach and perform at the Equine Village later this week.
From his Wolf Creek Ranch in Grass Valley, Calif., Beth-Halachmy raises and trains horses in his Cowboy Dressage school of horsemanship, which combines Western and classical methods.