Maloney was tossed from The Socialist after the horse stumbled about 200m past the line after winning Wednesday's Class Three Handicap.
It originally appeared Maloney had escaped serious injury as he was able to walk back to scale.
But after he complained he was having problems breathing he was taken to hospital for observation and X-rays.
Maloney's manager Glen Courtney said it was later determined Maloney had four broken ribs and a punctured lung.
“He is in a fair bit of pain and he will obviously miss some weeks,” Courtney said.