Trainer Robert Smerdon is to appear at an inquiry following the Caulfield Cup day scratching of his runner Shewan.
The stewards ordered Shewan's scratching after traces of blood were discovered on the horse's neck during a stable inspection on race morning.
Shewan had been due to run in the David Jones Cup.
The inspection also turned up similar indications concerning the Smerdon-trained Mosheen but the evidence was not considered strong enough to force her scratching.
Smerdon could offer no explanation to the stewards who adjourned their inquiry until they receive a report on samples taken from Shewan.
The stewards also suspended jockey Nick Hall for 11 meetings for causing interference on Electric Fusion, trained by Smerdon, in the Norman Robinson Stakes.
Electric Fusion lost second place in the race on protest to Honorius.
Hall pleaded guilty to a charge of careless riding and will be permitted to ride again on October 31, Bendigo Cup day.
AA