Hughie Morrison will appear before the British Horseracing Authority's disciplinary panel on December 19 and 20 after Our Little Sister failed a drugs test at the start of the year.
Our Little Sister tested positive for banned substance nandrolone following a race at Wolverhampton on January 14. The four-year-old filly finished last of eight runners in an extended two-mile handicap, in which she was sent off at odds of 12-1.
She raced once more, when down the field at Southwell 12 days later and has since been retired. That was her third run that month, having finished fourth there on January 2.
The East Ilsley trainer, who could lose his licence for anything between a year and 10 years if found in breach of the rules, fiercely denies any wrongdoing and offered a £10,000 cash reward for anyone that could help prove his innocence after the charges were first announced in May.