Samantha Chandler, who belongs to the Anglican Society for Welfare of Animals, has been speaking ahead of the event at Aintree Racecourse in Liverpool this afternoon.
Described as the biggest and most famous horse race, more than £200 million is expected to be bet on today's Grand National, with more than ten million people predicted to watch it on television.
Speaking to Premier Christian Radio, Samantha Chandler said: "The jumps have undergone some changes over the years ...but they are still very, very difficult fences and they require the horses to be extremely fit and extremely brave.
"There is obviously a welfare issue because horses are killed in the Grand National but they are in lots of National Hunt races.
"It is obviously a dangerous sport ...but, having said that, horses in training are generally very well-looked after, to the highest standards.
"The amount of animals killed every year or kept very badly in the factory farming industry is probably a far bigger welfare issue than the racing industry.
"Having said that, it isn't mean that they're aren't welfare issues in the racing world because I think there are."
Organisers of the Grand National said: "Aintree has been the home of the Grand National since it's first running in 1839, and although a version of the race took place in years prior to this, 1839 is the accepted date of the official commencement of The Grand National.
"Since those early days, the course and fences have undergone many changes.
"Most recently, the wooden stakes at the core of the fences have been replaced with flexible plastic to reduce the risk of horses and jockeys getting injured.
"The starting line has also moved further away from the main stand as this helps the horses remain calmer in the moments before the off.
"These changes haven't effected the essence of the race, which still remains the one of the toughest tests of horse and rider in the world.
"Forty horses line up at the starting tape and around 60% of the entrants will not complete the race, which is four and a half miles long and has thirty fence jumps."
Picture: The Weatherbys Private Bank Champion Standard Open National Hunt Flat Race ahead during Ladies Day of the Crabbie's Grand National Festival at Aintree Racecourse