The beta-agonist clenbuterol in mane and tail hair of horses.
BACKGROUND
The beta2-agonist clenbuterol is commonly administered for therapeutic purposes in the horse, but its use an an anabolic agent is illegal. Clenbuterol can be detected in blood and urine for a relatively short period after administration and detection in hair could enhance the analytical range and be used to determine the history of clenbuterol application.


OBJECTIVE
That detection in mane or tail hair is possible over an extended period.


METHODS
Four horses received 0.8 microg clenbuterol hydrochloride/kg bwt b.i.d. for 10 days. Four other horses were used as untreated controls. Blood, urine, mane and tail hair samples were taken on Day 0 (before) and 5, 10, 30, 35, 40, 60, 90, 120, 150 and 360 days after start of treatment. Gas chromotography/high resolution mass spectrometry (GC/HRMS) was developed for clenbuterol analysis: limit of detection was 0.2 pg/mg; intra-assay repeatability limit r = 0.06 (confidence level 95%); interassay repeatability limit r = 0.03 (confidence level 95%). Prior to treatment, clenbuterol was absent from all samples analysed.


RESULTS
Clenbuterol was detectable as early as Day 5 in tail and mane hair of Segment 1 (0-20 mm from the roots) and was maximal on Day 90. However, as time progressed, shift into lower 20 mm segments was observed. On Day 360, the maximum concentration (up to 21 pg/mg) was located in Segment 13, i.e. 26-28 cm from roots of hair. Clenbuterol was not detectable in blood or urine after Day 30. Mane and tail hair results were very similar.


CONCLUSIONS
The study showed that the beta-agonist clenbuterol can be found in mane and tail hair of horses after extended periods.


CONCLUSIONS
It will be possible to detect clenbuterol in breeding and show horses where anabolic drugs have been used illegally to improve conformation. This method may also be helpful to monitor therapeutic clenbuterol treatment.
Schlupp
A
A
Institute for Animal Science Mariensee, Federal Agricultural Research Centre, 31535 Neustadt, Germany.
Anielski
P
P
Thieme
D
D
Müller
R K
RK
Meyer
H
H
Ellendorff
F
F
D000284:Administration, Oral; D000318:Adrenergic beta-Agonists / Q000032:analysis* / Q000493:pharmacokinetics / Q000627:therapeutic use; D000818:Animals; D002976:Clenbuterol / Q000032:analysis* / Q000493:pharmacokinetics / Q000627:therapeutic use; D004305:Dose-Response Relationship, Drug; D004350:Drug Residues / Q000032:analysis*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods / Q000662:veterinary; D006197:Hair / Q000737:chemistry* / Q000378:metabolism; D006736:Horses / Q000378:metabolism*; D008297:Male; D011897:Random Allocation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D000318:Adrenergic beta-Agonists; D002976:Clenbuterol