Group One winning rider Peter Mertens and apprentice Jordan Childs have been taken to hospital after their mounts fell near the home turn in a race at Hamilton.
Both were conscious with Childs complaining of wrist and arm pain while Mertens had pain in his collarbone, chest and knee.
Both the horses were seriously injured and had to be euthanised.
Stewards and jockeys inspected the track near the home turn where the incident happened but were satisfied the area was safe and proceeded with the last race.
Mertens has ridden three Group One winners including Sirmione for Bart Cummings in the 2007 Mackinnon Stakes while teenager Childs, son of former jockey Greg Childs, rode his first city winner in August.