Trainer John McNair has lost an appeal against a $10,000 fine for a positive swab to methylamphetamine returned by one of his horses.

Racing NSW stewards originally fined the trainer $15,000 after a post-race swab taken from Normandy at Newcastle on March 18 showed the presence of the drug.

The stewards acknowledged the trainer was not responsible for giving the drug to the horse and also investigated an anonymous phone call made to Racing NSW on the morning of the meeting telling them McNair's horses had been illegally treated.

When informed of the call on race morning, McNair told stewards his horses had not been treated and he was confident they were going to the races drug-free.

But as the horse's trainer McNair is ultimately responsibility for presenting Normandy to race with a prohibited substance in his system.

His $15,000 fine was reduced to $10,000 on appeal but McNair took it to the NSW Racing Appeal Tribunal in an attempt to have it reduced or wiped altogether.

However the RAT on Friday said the penalty would stand.