Drug Testing in 2000

Drug testing is about to move into the 21st Century for horseracing. Research findings at the University of Kentucky’s Gluck Equine Research Center could make the use of urine in post-race drug testing a thing of the past within a very short time. Urine has been the body fluid of choice in drug testing because the horse’s kidney concentrates whatever is in the blood. Therefore, every drug in the horse’s system is concentrated at least 50-fold by the kidney, and fluid (urine) is excreted in a large volume for sampling. The disadvantages are that urine testing relates poorly to blood concentration, and drugs sometimes can be found for a long time in urine.

Blood is a much more satisfactory medium, but the concentrations of drug are much smaller. This makes detection and quantitation more challenging. An ideal method would be highly sensitive and specific and require only a small volume of sample. This method now has arrived.

New liquid chromatography mass spectrometry mass spectrometry (LC-MS-MS) offers an exquisitely sensitive test to laboratories. The new testing equipment, while expensive, is highly specific, very sensitive, and virtually eliminates background readings of “other” substances that might confuse results.

With this new technology demonstrated in the laboratory, there now is available to the industry a test sensitive enough to use blood instead of urine in drug detection for most agents. For horse owners, it means making cutoffs much fairer because it eliminates the inherent variability of testing urine. Drugs such as Bute are given in gram quantities and the threshold is set in micrograms per ml (parts per million). This new technology extends testing for substances that are given in milligram quantities or less and tested in picograms or parts per trillion.

This technology can fulfill two primary goals of the Kentucky Equine Drug Testing and Research Council and the National Thoroughbred Racing Association Equine Drug Testing and Research Initiatives to improve uniformity in methodology of drug testing and offer a level playing field for horses.

At a meeting on Feb. 7, James Gallagher, executive director of the NTRA Drug Testing Task Force, discussed the goals of his group with a sophisticated audience of horse owners, racing executives, veterinarians, and researchers at the Gluck Center in Lexington, Ky. Among other problems he said needed to be faced were disparity among states to fund testing, lack of continuity among racing commissions causing problems for trainers and owners, and the widespread differences in state laws on medications ranging from zero tolerance to agreed levels of therapeutic drugs.

“We need to monitor the performance of analysists and test their parameters,” said Gallagher of racing chemists. “There is a lack of cooperation, direction, and organization for new testing procedures among labs.”

The NTRA task force hopes to obtain cleared split samples from racing jurisdictions all over the country, re-label them so they cannot be traced, and have sophisticated

university laboratories put the samples to more strenuous tests. This will give a “national survey” of samples to identify drugs being used and show gaps in testing, said Gallagher.

Tom Tobin, a leading drug researcher based at the Gluck Center, and his international team redirected work in their laboratory last year to focus on two projects—dosed horse samples for testing class I drugs, and developing a serum test for clenbuterol.

For the class I drugs, the lab team worked to detect them and establish the efficacy of the current screening process. Coverage proved to be quite satisfactory.

“Last summer we couldn’t accurately measure clenbuterol in serum, now we can,” said Tobin.

The LC-MS-MS was used to develop a sensitive test for clenbuterol in blood serum. This test is much more sensitive (can detect lower amounts in the horse’s body) than tests used for Bute or Lasix. For example, testing for Bute looks for micrograms (parts per million) per milliliter of the serum sample; testing for Lasix looks for nanograms (parts per billion) per milliliter of serum sample; the new testing of serum for clenbuterol detects picograms (parts per trillion) per milliliter of sample.

This new test for clenbuterol is close to one million times more sensitive than the threshold for Bute,” explained Tobin. He added that there is no reason this type of test cannot be adapted to other medications in plasma or urine. “I expect we could measure down to fentograms or parts per quadrillion in urine. This is highly sensitive technology.”

About the Author

Kimberly S. Brown

Kimberly S. Brown was the Publisher/Editor of The Horse: Your Guide To Equine Health Care from June 2008 to March 2010, and she served in various positions at Blood-Horse Publications since 1980.

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