Authorities say the horse that died at the Hastings Racecourse on Saturday after crashing into the winners circle was blinded by her blinkers.
Online video of the race shows the horse, named Private Mambo, clipping her heels after leaving the gate during the sixth race and sending her jockey into the dirt.
The horse then veers wildly, grazing the inner rail of the track before crashing into the winners circle.
She also struck security guard Dave Dahl, who remains in hospital in serious but stable condition.
"He had surgery yesterday for internal damage. He has broken ribs and actually has the hoof prints on his chest, which shows you the magnitude of what happened," Howard Blank, media vice president for the B.C. Lottery Corporation said.
The jockey, Geovanni Franco, was not hurt.
The whole incident has been a shock to Private Mambo's owner, Aldergrove resident John Snow, who says she was the sweetest-natured animal he's ever owned.
"Just a real sweetheart. A great horse to have in the barn," he said. "It's a real tragedy."
There was a public prayer for Dahl at the track on Sunday, and a moment of silence for Private Mambo. Blank says it's a tragedy spectators won't soon forget, and one officials hope never happens again.
"In all our years at Hastings, this has never happened before. It's probably never happened at any track at all," he said.
With a report from CTV British Columbia's Peter Grainger
