There were 28 horses in the field of the four-mile race, which has 27 fences. The £180,000 race was won by Beshabar, with Merigo second, Always Right third, and Lothian Falcon fourth.
The deaths follow just a week after the Grand National at Aintree, in which two horses, Ornais and Dooneys Gate, died from injuries suffered in falls at fences.
The deaths sparked a debate over the safety of jumps racing, and Animal rights group Animal Aid continued its attack on racing following the Scottish deaths.
"One hundred and eighty three horses have been killed on British racecourses since March 2010," group spokesperson Dene Stansall said.
"That so much animal suffering and destruction should take place in the name of sport is quite simply unjustifiable."
Responsibility for the welfare of horses in British racing lay with the British Horseracing Authority, and it had failed in that duty, he argued.
"It is time to strip the BHA of those powers and for steps to be taken to afford proper protection for racehorses."