The race is run over an extreme distance of 4½ miles and confronts horses with a bewildering combination of 30 formidable obstacles, some of which include perilous drops, ditches and sharp turns. Deaths at the three-day event are routine. Since 1997, the Aintree meeting has claimed the lives of 35 horses.
Some 38% of the annual fatalities occur during or immediately after a race; the remaining horses are killed because of injuries received in training, or after being assessed by their owners as no-hopers.
Visit Race horse Deathwatch, our web database tracking on-course race horse deaths
Animal Aid's research shows that the odds are stacked against the participants from the start. While jump horses were once bred to be robust in order to cope with the rigours of jump courses, the modern industry concentrates on breeding a lighter-boned, speedier animal for the more lucrative Flat events. Because they are fine-tuned for speed rather than skeletal strength, they run an extreme risk of suffering fatal injury when they do fall - a common occurrence on an especially long and challenging course such as Aintree.
Of the approximately 18,000 horses bred by the closely-related British and Irish racing industries each year, only around one third go on to become racers. Many of the 'defective' newborns end up slaughtered for meat, while those who do enter racing suffer a high level of fatal injuries and stress-related illnesses such as gastric ulcers and bleeding lungs.
Horses are social animals who are meant to be continuously grazing and moving.
This can lead to potential collapse and heart attack.
When not housed in their stable, they are confined behind high fences. And to minimise any chance of a costly injury, insurance policies usually state that they must not be ridden. It is a life of near isolation and deadening routine that - barring physical breakdown - can go on for 20 or more years.
British bookmakers now generate a combined annual profit of £1 billion from horse racing. The Horserace Betting Levy Board takes 10% of bookmakers' annual gross profits obtained from racing and re-channels them into the industry and its associated activities. For 2006/7, the Levy Board was able to draw on close to £100 million. Scandalously, it thought fit to donate just £56,000 to Race Horse Rehabilitation and Retraining. Compare the £56,000 horse 'rehabilitation' money with the £1.8 million granted by the Levy Board to horse breeders.
Many go into a wretched downward spiral, passed from owner to owner. The final stop might be the slaughterhouse.
Watch our undercover footage of horse slaughter from an English Abattoir