The trainer of Hill Sixteen says protesters who held up the start of Saturday's Grand National race were responsible for the death of the horse.
The 10-year-old, ridden by Ryan Mania, fell at the first fence and after being tended to on the course, had to be put to sleep.
The incident came after animal rights campaigners had succeeded in delaying the race at Aintree as police arrested 118 people amid scenes of chaos.
The start was held up for 14 minutes after a large number of activists attempted to gain access to the course before the main event.
Speaking to BBC Radio 4's Today programme, trainer Sandy Thomson pointed to the fact his horse had never had a problem on the course in previous rides, and suggested the fall was due to being "buzzed up" from the protesters' actions.
"It was all caused by these so-called animal lovers who are actually ignorant and have absolutely no idea about the welfare of horses," he said.
"There were quite a lot of the horses buzzed up... When they got down to the start, nobody quite knew what was happening.
"The starter wanted to get them off as quickly as possible, then the horses were drawn forward then told to get back.
"One of the other things missing was the parade. I think that gives the horses and the jockeys that couple of minutes to gather their thoughts and that didn't help the situation either."
Activist group Animal Rising, whose supporters disrupted the race, said: "We want to offer our deepest condolences to anyone connected to Hill Sixteen or who has been impacted by their death.
"Horse deaths and injuries are an unavoidable consequence of the way we use animals for sport."
The Grand National is among the world's most famous races but also has its detractors, with concerns over the number of horses that suffer serious injuries or die from falls.
Two horses died at the Liverpool course in earlier races during the week's festival, before Hill Sixteen became the third fatality.
"If we look at the last nine years since the course has been modified there's been an average of under two fallers at the first two fences," Thomson added.
"This year everyone got very uptight about [the protests] – horses, jockeys – and there were eight fallers at those first two fences.
"We as a sport are continually moving forward, we're continually trying to make the sport safer."
Corach Rambler won the 175th running of the famous steeplechase.