The letter, dated August 29 that year, expressed deep concern about tension at the Wentworth Park track because of his allegations.

''The comments made by Dr Humphries create the impression that use of drugs in the industry is commonplace and that stewards are giving favourable treatment to certain trainers. The situation is becoming quite untenable and impacting on the smooth and effective control of race meetings …''

It would be another five years before the Independent Commission Against Corruption investigated, but the result would vindicate Dr Humphries. The chief steward Rodney Potter and five others were charged with corruption. Potter pleaded guilty and was jailed for 2½ years. Sweeping industry reforms included an independent board to oversee a new body, Greyhound Racing NSW, or GRNSW.

But Dr Humphries is worried again. He fears a lack of independent oversight, particularly because the Veterinary Advisory Panel - of which he was a member - has been disbanded. All official vet positions have been taken in-house. ''Now the only oversight is by people employed by GRNSW,'' says Dr Humphries. He believes independent vets had more freedom to speak out.

Brent Hogan, the organisation's chief executive, said these vets were removed because of a potential conflict of interest: as they ran private practices, they would often treat the same dogs they oversaw at the tracks. Mr Hogan has said that the introduction of a Greyhound Welfare and Veterinary Services Unit, within GRNSW, ensures vets are at all the state's greyhound meetings and are on hand to provide expert advice.

But Dr Humphries told The Sun-Herald: ''It was the independent vets that brought the inconsistencies to the attention of the authorities.''

He agrees with complaints that the bigger trainers do not appear to be getting their dogs swabbed as often as others. ''It was like this when Rodney Potter was there. This would have been ICAC material before, but now ICAC has no authority and there is no action.''