Trainers, and their vets, have unknowingly until now been playing racing's version of Russian roulette.
Super-sensitive Hong Kong drug testing machines have New Zealand horse trainers living in fear of losing their licences.
And that could be for something as harmless as using a seemingly legal prescribed treatment they have been administering for years.
The problem has been highlighted by confirmation that two horses, including a group one winner from last month's Harness Jewels meeting, have returned positive swabs.
Delightful Christian returned a positive to arsenic after winning the $150,000 2-year-old filly division of the glamour raceday, even though she was only treated with a supplement commonly used by racing stables in this country every day without problems.
The other positive was returned by Precious Mach, who finished fourth in the 4-year-old mares race.
While nobody close to the horses involved will speak publicly, a Weekend Herald investigation suggests the arsenic is present in minute quantities in Caco Copper Iron (also known as Caco-Iron-Copper) which is a solution widely prescribed by vets treating racehorses.
It is seen as a booster for horses while pre-exercise and as one veterinarian told the Weekend Herald, "I have used it on thousands of horses for decades.
"It is no more serious than a human having a Berocca and has never been a problem. Until now."
The "until now" comes about because a very small percentage of post-race samples taken from New Zealand horses are sent to the world-leading testing laboratories in Hong Kong.
Using more modern, expensive and therefore sensitive equipment, the Hong Kong laboratory is more likely to pick up traces of drugs such as arsenic.
And a senior New Zealand racing drug enforcement official confirmed those same samples tested in the New Zealand laboratory would almost certainly come back negative.
That means trainers, and their vets, have unknowingly been playing racing's version of Russian roulette, with the chance that everyday substances used for decades could result in a positive if the sample is sent to Hong Kong.
Of the more than 8000 swabs taken in New Zealand every racing season, it is understood fewer than 150 are sent to Hong Kong.
"As it turns out these guys have been the unlucky ones," said the drug-testing official.
The Racing Integrity Unit cannot afford to send all New Zealand swabs to Hong Kong and initially it was thought the overseas testing would be used to chase down trainers suspected of using serious drugs such as EPO or ITTP.
But the tests are now showing up traces of drugs like arsenic, which is how champion Canterbury trainer Tim Butt ended up disqualified from training for six months.
Numerous trainers contacted yesterday all expressed the same concerns: they are happy to have the Hong Kong testing undertaken to find serious drug cheats but they worry the super-sensitivity is catching innocent parties using therapeutic drugs with no performance-enhancing qualities.
There is plenty of sympathy, even at official levels, for Delightful Christian's co-trainer, Brian Hughes, whose vet, Ivan Bridge, gave the filly the Caco Copper Iron, which he regularly prescribes for horses without problems.
Hughes' reputation won't suffer a dent from the positive and it is highly unlikely it will affect his licence, but the filly could still lose the $75,000 winning stake and a group one Jewels victory, which over the course of her future broodmare career could cost her owners at least $500,000.
While no charges have yet been laid and the Judicial Control Authority would ultimately rule on the case, it is rare for a horse with a positive swab in this part of the world to keep the race unless contamination is proved.
Sadly, for the connections of Delightful Christian and Precious Mach, had a different bunch of Harness Jewels swabs been chosen for Hong Kong, their results would have been negative.
The new positives are certain to have trainers' groups seeking increased clarification from the Racing Integrity Unit and racing code bosses about what everyday substances now run the risk of returning a positive.
The issue is a messy one, with argument and counter-argument, but one thing is for sure, it is not going to be fixed any time soon.
It is a multi-layered problem that runs far deeper than Delightful Christian losing the race of herlife.