WHAT IS EPO?

EPO, SHORT for erythropoietin, is an an oxygen-boosting hormone.

It doesn’t make slow horses fast but it makes them brave - they gallop harder for longer.

The problem for racing authorities is it’s hard to police.

Because the body produces EPO naturally in the kidney and liver to make red blood cells, its presence in test samples is not automatically suspect.

It is the level that counts - and because EPO breaks down rapidly, it is notoriously hard to detect an elevated level in horses.

EPO was originally refined to treat anaemia, but opportunists grasped its potential to boost stamina after Finnish runner Lasse Viren legally used blood doping to smash Olympic distance records in the 1970s before returning to obscurity when the rules caught up with the laboratory rats.

European cyclists who took up the drug around 1990 were not all so skilful: some died when their blood turned to sludge and their hearts stopped.

But then science tuned the drug and the dosage so that Lance Armstrong and his generation of cyclists could get away with using it.

Intelligence suggests racing cheats have now moved on to cobalt chloride, which has a similar effect to EPO in that it boosts red blood cell production.

New Zealand racing regulators are co-operating in an Australasian-wide study to set a threshold level, and are testing for it, but New South Wales has already banned trainers found to have used the substance. Some 10 new cases are under inquiry.