A ten-year-old horse competing in Saturday’s Grand National died after a fall at the first hurdle.
Up For Review was left seriously injured after the incident and was seen thrashing in agony on the course during the weekend’s historic race.
Animal rights activists blasted race organisers, reiterating calls for tighter safety measures after Saturday’s death brought the number of horse fatalities at Aintree this year to three.
Forest des Aigles and Crucial Role died on Friday.
Chris Luffingham, director of campaigns at the League Against Cruel Sports, said: “Much has been made about the Grand National being made safer, yet we are again talking about the tragic death of a horse during the race.
This death shows starkly why the League has repeatedly called for tighter safety measures and the formation of an independent regulatory body with horse welfare at its heart.
“The death toll at the Aintree festival has now reached three horses which is simply unacceptable.”
The British Horseracing Authority, which regulates the sport, said that prior to Saturday there had been no fatal injuries during the Grand National since 2012 and that overall fatality rates had reduced by a third in the past two decades.
David Sykes, the authorities welfare boss, said: “Our sympathies go to the owners, trainer, jockey and all the stable staff who care for racehorses through their life.
“As a result of ongoing focus and investment in welfare by Aintree racecourse and the BHA, the safety record at the Grand National festival has improved significantly.
“Aintree racecourse and the BHA worked together in the run-up to this year’s meeting to ensure the preparations to keep the event safe were the best ever.
“We will take a measured, evidence-based approach to assessing the incidents, which will include reviewing video footage of all incidents and working with jockeys and trainers to ascertain exactly what caused the injuries.”