Two horses have died in each of the last two years at the race, leading to increasingly loud calls from campaigners to put an end to the world's most famous National Hunt event.
O'Neill knows only too well about the regular fatalities at Aintree: last year he watched in horror as his horse Synchronised, who had won the Cheltenham Gold Cup the previous month, suffered a fatal fall.
But the Irishman told The Times that those who criticise British racing's showpiece event do not know what they are talking about.
"It's always been a fantastic race and it still is," said O'Neill, who trained 2010 National winner Don't Push It.
"People saying the National should be stopped just don't understand.
"We are all in racing because we love the horses, but we take things to heart.
"Some of the things said about us are a bloody insult, as if we are animals ourselves.
"There are people out there stabbing and shooting, killing randomly, and sometimes it seems we are being put in the same bracket."
O'Neill, who rode in the National as a jockey eight times without ever managing to finish, will have two runners in Saturday's race: Sunnyhillboy and Lost Glory.
The deaths have prompted several changes to the course, and there will be more this year as the start has been moved forward 90 yards while timber frames in the fences have been removed.
But the changes have always seemingly been to little avail: safety improvements began in earnest after the 1989 race saw two horses killed, yet since then horses have continued to die in the race at an average of one a year.