"We didn't really know what to do next but we knew we had to advise the Racing Integrity Unit for our safety in case something went wrong and to make sure the horses hadn't been contaminated," said Purdon, the long-time champion trainer in New Zealand.
The RIU took urine samples from all nine horse trained by the All Stars today and one, Dibaba, trained by fellow trainers Terry and Glenys Chmiel as it was on the same transporter north.
The RIU also asked the TAB to suspend betting on all the six Jewels races which have horses who have been tested in them and they are likely to remain suspended until results of the tests come back on Friday afternoon.
With pre-raceday fixed odds betting only a fraction of total turnover the suspension is unlikely to greatly affect overall turnover on the meeting.
"It is very unfortunate and has made for a long week but Natalie and I believe we have handled the matter the only way we could both legally as employers and also in regards to our obligations to the industry.
"But we are hopeful and confident the horses haven't been contaminated and will all be cleared to race."
The Harness Jewels feature nine group one races for a minimum of $125,000 to be run at Cambridge Raceway with a crowd of up to 5000 expected.