The Texas A&M Veterinary Medical Diagnostic Laboratory’s (TVMDL) Analytical Chemistry Section offers a screen for the detection of beta-adrenergic agonist drugs, including albuterol, bambuterol, clenbuterol, ractopamine, and zilpaterol, in hair. Certain drugs bind to melanin in hair and can be detected months, and in some cases years, following drug administration. This provides horse racing regulators the ability to monitor the use of prohibited substances administered well in advance of competition, where detection in blood and urine during competition is not likely.
Segmental analysis can be performed on hair to create a drug profile that can be used to estimate when the drug might have been administered. Segmental testing can be useful when horses change ownership to demonstrate if drug administration occurred prior to change of possession.
Equine hair grows at a rate of approximately 2 cm per month. Mane or tail hair is measured from the root end and cut into 2 cm segments. Each segment is extracted and tested individually using liquid chromatography – tandem mass spectrometry (LC-MS/MS). This allows TVMDL to create a drug profile on a month-by-month basis.
For example, TVMDL received mane and tail hair from a two year old Quarter Horse stallion. The mane was cut into four, 2 cm segments. The tail was cut into three, 2 cm segments. Clenbuterol was detected in each mane and tail segment, with the highest response detected in the segments farthest from the root end (10 cm and 8 cm). A profile was generated for both samples as presented below:
From the diagrams, it is evident that as the mane and tail hair continued to grow, the relative clenbuterol response decreased at a similar rate. It is also apparent that clenbuterol was in the horse’s system at approximately four months prior to sample collection.
For more information about TVMDL’s test catalog, visit tvmdl.tamu.edu or call 1.888.646.5623.
