The deaths of two of the runners in this year’s Grand National has proved the catalyst for changes to be made to the world’s most famous steeplechase.

Outsiders Dooneys Gate and Ornais suffered fatal falls at the fourth and Becher’s Brook respectively – ruling both fences out of the race on the second circuit.

Following a review of the race and the incidents the authorities have decided to act.

A reduction of between four and five inches to the drop on the landing of Becher’s Brook is among the changes.

“It is not possible to completely eliminate risk in horse racing,” said Aintree managing director Julian Thick.

“However, I am confident the course changes we are announcing will, over time, have a positive impact.”

The fourth will be reduced in height by two inches to 4ft 10in (1.47 metres) after a statistical review found that it and Becher’s were the most difficult jumps to clear on the course.

The drop on the landing side of the first will also be reduced while the height of the toe boards around the course will increase to make it easier for horses to determine the base of the fences.

“Raising the landing zone at Becher’s Brook is undoubtedly a positive step forward,” said RSPCA equine consultant David Muir.

“However the RSPCA remains concerned about drop fences.”

The modifications follow an analysis of all races run on the Grand National course since 1990 and consultations with animal welfare groups, the Royal Society for the Protection of Animals and World Horse Welfare.

Jamie Stier, director of Raceday Operations and Regulation for the British Horseracing Authority, said that lessons had been learned from such incidents.

“Aintree, our team of Course Inspectors and our Senior Veterinary Advisor have analysed DVD footage of races and fallers over the Grand National course since 2000,” he said.

“I truly believe it all makes for a strong package of track changes that will enhance rider and equine welfare.”