Trainer Peter Moody has been fined $12,000 after one of his horses tested positive to ibuprofen on two occasions.

House Of Hingis returned the positive swabs to the non-steroidal anti-inflammatory drug when she raced at Rosehill on November 14 and Warwick Farm two weeks later.

Moody told Racing NSW stewards the mare had received ibuprofen in July and August when she was being treated in Victoria for a suspensory injury.

But NSW chief vet Craig Suann told Monday's inquiry the scientific evidence was that the therapeutic drug would be out of a horse's system within a few days.

Samples taken from all horses in Moody's Randwick stable on December 16 all returned negative results to ibuprofen.

The trainer reserved his plea but was found guilty and fined $6000 for each of the positive tests and House Of Hingis disqualified from her fifth and third placings in the two races.

"It's regrettable it can't be determined where it came from but the buck stops with the trainer," chief steward Ray Murrihy said.

Moody, who operates stable in two states, is one of four Victorian trainers involved in an ongoing investigation into elevated levels of cobalt returned by horses in their care.