Blood samples taken from two horses at the centre of a Sydney racing controversy have returned levels within normal limits.

The TC02 levels of Ferocimo and Belegic were tested after trainer Greg McFarlane was caught trying to drench Ferocimo before it was due to race at Rosehill last Saturday.

Racecourse detective Albert Gardner told a Rosehill stewards' inquiry he caught McFarlane and a stable employee in a box with a horse which had a nasal tube inserted.

McFarlane said the horse was Belegic before admitting it was Ferocimo, who was subsequently scratched.

The trainer conceded he was trying to stomach tube Ferocimo, a practice used to administer bicarbonate to help offset the build-up of lactic acid.

Further analysis of urine samples taken from Ferocimo and 20 sachets of a white powder confiscated by stewards are still being processed.