Eight Belles had no pre-existing bone abnormalities that caused the filly to break down after finishing second in the Kentucky Derby.
Autopsy results reviewed by The Associated Press on Thursday confirm compound fractures of both front legs at the fetlock joints. They also describe lacerated skin on both legs, an absence of joint fluid in the damaged areas, congested lungs and hemorrhaging in the left thyroid gland. The filly's head also was bruised.
Kentucky chief veterinarian Lafe Nichols performed the tests at the University of Kentucky's Livestock Disease Diagnostic Center.
Eight Belles was euthanized on the track at Churchill Downs after collapsing while jogging about a quarter-mile past the finish line. Stewards found no evidence she was injured during the race.
In addition to the autopsy, there will be routine post-race drug-testing and further medication tests requested by Eight Belles trainer, Larry Jones. Jones has said he wants the extra scrutiny to prove the large, muscular filly wasn't on steroids at the time.
A lab at Iowa State University is conducting the drug examination on behalf of the Kentucky Horse Racing Authority, with results not expected for at least several days. The autopsy said no toxicology test had been requested but the samples were being saved in case one is.
Also Thursday, the racing industry was proceeding with plans to ramp up horse safety following the deaths of Eight Belles and 2006 Kentucky Derby winner Barbaro, among others.
Lisa Underwood, executive director of Kentucky's racing authority, said the organization will meet Monday and establish a group to study health and safety issues.
"Nothing is more important to the racing industry than the safety of the competitors," Underwood said.
The Jockey Club has formed a panel to examine the issues, and its members participated in a conference call Wednesday. Stuart Janney, a thoroughbred owner and breeder who will chair the committee, said breeding practices, track surfaces and medication are among the subjects to be discussed.
He acknowledged, however, that enforcement could be a challenge. Most of the enforcement for the sport comes from different state racing organizations.
"We're going to use this committee as a bully pulpit to be persuasive on certain matters, and go to other people in the industry and say, 'This is how we feel, how are you going to help us?"' Janney said.
The Jockey Club already has hosted two summits on safety and welfare in racing. Its newest safety panel will meet this month in Lexington, with the first recommendations due by August.