Hair Analysis Detects Drugs in Horses

In the race for the ultimate drug test, Chinese researchers just got a few lengths ahead. In fact, you might even say they got a hundred lengths ahead.

That’s because they’ve validated a new hair test that can detect a broad range of “well over 100 prohibited substances in a single analytical run,” their recently published study states. And the clincher is this: It can detect doping weeks and even months after it occurred.

“Doping control analysis of a blood or urine sample gives only a snapshot of prohibited substances that may be present in the body at the moment of sample collection,” said Jenny K.Y. Wong, PhD, a racing chemist at The Hong Kong Jockey Club’s Racing Laboratory at Sha Tin Racecourse, in China.

“With the much longer detection window of hair testing, however, there is a greater chance of obtaining from a single hair sample evidence of the prior use of a prohibited substance,” she said. “As such, hair testing is best applied to out-of-competition testing for prohibited substances that have no place in a horse.”

Wong tested equine hair samples in association with her fellow researchers, including Terence S.M. Wan, PhD, EurChem, CSci, CChem, FRSC, FAORC, FCSFS, previously the head of the Racing Laboratory and chief racing chemist at The Hong Kong Jockey Club. They put mane hairs through laboratory conditions to make them acquire drugs, somewhat similar to the way hair would receive them in a horse that had been administered those substances, she said. Their testing of the pulverized hair samples showed that it detected, in a single test, all 121 of the prohibited substances and, depending on the length of hair collected, up to six months before.

They also collected mane samples from local horses and found evidence of authorized out-of-competition drugs, she said, including clenbuterol and acepromazine and its metabolites, among others.

“Compared to blood or urine, hair is the biological matrix that can provide the longest detection window—months instead of days,” Wong said.

It’s also easier to collect, store, and transport, she added.

Wong cautioned that the recently validated test is less useful for detecting substances allowed during training but not competition. For example, the Féderation Equestre Internationale and most horse racing authorities permit non-steroidal anti-inflammatory use during training but prohibit it at competitive events.

“The testing of horse hair is more suitable for out-of-competition testing, especially for substances prohibited at any time in the career of a racehorse as specified in Article 6E of the International Agreement on Breeding, Racing and Wagering, published by the International Federation of Horseracing Authorities,” she said.

“Therapeutic substances that can be used in training outside a specified withdrawal period before racing are better controlled with race-day blood or urine samples, especially because screening limits in blood and urine have been established for controlling the use of common equine therapeutic substances,” she said. “Segmental hair analysis (i.e., analyzing different segments along the length of hair) is generally not possible for determining the exact date of last exposure before racing. Thus, hair is more suitable for testing substances which are prohibited for use at all times.”

As such, hair-based doping control isn’t meant to replace blood and urine tests, Wong said. Rather, it’s meant to complement these shorter-time-window tests to give a more complete overview of the horse’s recent and long-term drug history.

“Since many prohibited substances are excreted rapidly from the body, multiple blood or urine samples collected at different time points may be necessary for an effective control,” said Wong. “However, the same result might be obtained with a single hair sample.”

The study, “Doping control analysis of 121 prohibited substances in equine hair by liquid chromatography–tandem mass spectrometry,” was published in the Journal of Pharmaceutical and Biomedical Analysis