Eighth horse dies at Churchill Downs amid rising controversy over track safety

Rio Moon, a 3-year-old colt, died after a race at Churchill Downs on Sunday, marking the eighth fatality at the home of the Kentucky Derby since the start of May
Rio Moon suffered a catastrophic injury to his left foreleg shortly after crossing the finish line in the sixth race
The fatalities have led animal rights groups and industry experts to question the track's safety record and commitment to equine welfare
Two of the eight fatalities belonged to horses in the barn of trainer Saffie Joseph Jr., who was indefinitely suspended by Churchill Downs
Three more horses were euthanized on Derby day, and another three suffered fatal injuries during morning training in the week leading up to the Derby.