Broadway Boy and Celebre d’Allen were both being assessed by vets following their runs in the Randox Grand National.
The Nigel Twiston-Davies-trained Broadway Boy raced prominently for a long way in the four-and-a-quarter-mile marathon before taking a horrible-looking fall at the 25th fence.
He received immediate care on the track for some time after the race had finished, with the 5pm contest delayed by over 10 minutes as treatment continued.
Broadway Boy was reported by Jockey Club Racecourses, who operate Aintree, to have walked into the horse ambulance before being taken to the racecourse stables for further assessment.
Celebre d’Allen was sent off a 125-1 shot under Micheal Nolan, with the rider pulling up the Philip Hobbs and Johnson White-trained runner after jumping the final fence.
The 13-year-old then collapsed on the racecourse, but following treatment, he was able to walk into the ambulance to be taken back to the stables for veterinary care.
The British Horseracing Authority tweeted: “Both horses received immediate and extensive treatment by the vets, also calling on the first class facilities and various teams on site.
“This treatment and assessment will continue into the evening.”
Broadway Boy’s rider Tom Bellamy was also taken to hospital following his fall.