Apprentice Fred Kersley will miss between four to six weeks of race riding, after sustaining a fractured thumb and elbow hairline fracture.
Kersley came off the Barry Fox-trained Foudre Boulon in the Clanbrooke Racing Handicap (1000m), but was reported to be sitting and up and communicating with medics following the incident.
Unfortunately, the mare was humanely euthanised after breaking down in the home straight.
The 18-year-old WA native later went to Epworth Hospital for X-rays, and was found to have suffered two fractures.
Kersley was booked for seven rides at Moonee Valley on Saturday, including Miles of Krishan, Guangzhou, Shards, Bling Dynasty, Sword of Justice, Sirbible and Wall Street Wolf, but replacements will be required.