Trainer Shawn Mathrick has been fined $4000 after pleading guilty to stomach tubing a horse the day before it was due to race.

Mathrick was issued with the fine by the Racing Appeals and Disciplinary Board in Melbourne on Thursday after it was established Mathrick had treated Umatic on the morning of November 7 when the horse was to race the following night at Cranbourne.

Under amended rules introduced this year, a horse is not allowed to be stomach tubed on raceday or during the one clear day before it is due to race.

The Board decided a fine was the appropriate penalty.

Umatic was scratched from the Cranbourne race following a stable inspection from stewards on November 7.

A stewards report from that day said Mathrick thought the rule had been 24 hours before racing.