TRAINERS who dope racehorses with a bodybuilding hormone won鈥檛 evade
detection so easily now that Australian researchers have worked out a test for
the offending substance, a meeting of the British Endocrine Societies in
Birmingham heard this week.
Somatotrophin is a natural hormone but extra doses are given to cows to
increase milk yields. And in some countries it can be used legitimately to help
repair tendon or bone injuries in horses, or to improve the condition of old
horses that no longer race.
But because somatotrophin increases muscle strength鈥攁nd would thus
affect the outcome of races鈥攊t is illegal to give it to racing
thoroughbreds. It can also be dangerous: excessive doses can cripple an animal
by causing abnormal growth of the cartilage of leg joints.
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The test was developed by a team led by Martin Sillence, head of animal
science at Charles Stuart University in Bathurst, New South Wales. Without a
reliable test, says Sillence, horse racing authorities have had to rely on
circumstantial evidence of somatotrophin abuse.
The new test works by measuring levels of insulin-like growth factor (IGF-1),
which is produced by the liver in response to somatotrophin. Working with
colleagues in South Africa and Britain鈥檚 Horse Racing Forensic Laboratories in
Newmarket, the team measured levels of natural IGF-1 in 2000 horses from around
the world.
Typical levels were around 90 to 100 nanograms per millilitre of blood
compared with levels of 850 nanograms per millilitre or more in horses
artificially dosed with somatotrophin. If you set the threshold at 700 nanograms
per millilitre, there is only a one in 32 000 chance that higher levels in a
horse will be due to natural variation in hormone concentrations. The Newmarket
laboratory is now perfecting a simple enzyme-based test for IGF-1 levels.
But cheating human athletes may be safe for a while yet. There are much
greater natural variations in IGF-1 levels in people than in horses. This is
because all thoroughbreds are genetically similar and descended from a handful
of Arab horses imported into England in the 17th century.
Peter Webbon, chief vet at the Jockey Club, British racing鈥檚 regulatory body,
says there is no evidence of somatotrophin abuse in British racing. He says the
risks of limb damage would deter owners from using the hormone.
The Jockey Club won鈥檛 say what tests it uses at racecourses, but Webbon
suggests that the new test is likely to be used. If horses did test positive,
trainers would be fined or lose their racing licence.
However, Webbon favours even more draconian penalties to deter anyone
thinking of misusing the drug. 鈥淎 treated horse is an unnatural representation
of its genotype and so I would support the removal of its name and any offspring
from the Stud Book,鈥� he says. This would mean that the horse would no longer be
classed as a thoroughbred and would be practically worthless for breeding.