FREE SHIPPING over $40
OVER 9000 FIVE-STAR REVIEWS
5% OFF ALL SUBSCRIPTIONS
100% HAPPINESS GUARANTEE
Analyze Diet
0
Home / Equine Research Bank / Drug Test Anal / Presence and detection of endogenous steroids in the horse-A...
Drug testing and analysis2023; doi: 10.1002/dta.3624

Presence and detection of endogenous steroids in the horse-A review.

Abstract: Detection of doping with steroids that are also endogenous in the horse can be challenging, and a variety of approaches to distinguish exogenous administration from their natural presence are employed. Knowledge of endogenous concentrations of various steroids in different genders of horses (intact male, castrated male and female) and factors that could naturally affect them is beneficial for establishing ways for detection of their use. The current internationally adopted approaches include concentration-based thresholds in urine and plasma, steroid ratios in urine and targeting the administered intact steroid esters in plasma and hair. However, these have their limitations, and therefore, other strategies, such as additional biomarkers and steroid profiling based on longitudinal testing and multivariate analysis, have been investigated and could potentially improve detection of the use of endogenous steroids in horses. This paper aims to provide a comprehensive overview of the steroids (androgens, oestrogens and progestogens) that have been reported to be endogenous to horses in literature, their concentration ranges in different genders and factors potentially affecting them as well as current and possible future approaches to detect their use.
© 2023 John Wiley & Sons, Ltd.
Get Full Text
Publication Date: 2023-12-13 PubMed ID: 38092431DOI: 10.1002/dta.3624Google Scholar: Lookup
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
LinkedInCopy
  • Journal Article
  • Review

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research article presents a detailed review of the challenges in detecting doping with endogenous steroids (those naturally occurring) in horses, and the various strategies used and proposed for their detection.

Detection of Endogenous Steroids

The detection of doping with steroids that are also naturally occurring in horses can be challenging because any trace of the steroid in a horse’s system could be a result of either doping or natural biological processes. As such, researchers employ various methods to determine whether the presence of these steroids is due to exogenous administration (doping) or their natural presence.

  • The primary methods currently used internationally include setting thresholds for steroid concentrations in urine and plasma (the liquid part of blood), comparing ratios of different steroids in urine, and targeting the administered intact steroid esters (a type of compound that results from the reaction between an acid and an alcohol) in plasma and hair.
  • The understanding of the natural (endogenous) levels of various steroids in different genders of horses and factors that could naturally affect them is critical in establishing the methods used to detect their unnatural use.

Limitations in Current Detection Methods and Proposed Strategies

There are limitations in the methods currently in use for the detection of steroid use in horses.

  • Potential variations in the natural steroid concentrations in horses due to factors such as age, diet, and health condition can complicate the threshold and ratio methods.
  • Though the targeting of intact steroid esters in plasma and hair can provide evidence of exogenous steroid administration, this method also has its challenges, as the administered steroids could have degraded, making them difficult to detect.

To address these limitations, other strategies have been explored:

  • Additional biomarkers (substances used as indicators of a particular biological state) have been investigated as potential tools for detection.
  • The profiling of steroids based on longitudinal testing (monitoring changes over a long period of time) and multivariate analysis (a statistical technique used to analyze data with more than one variable) has also been examined as a possible improvement to the current detection methods.

Overview of Endogenous Steroids in Horses

The paper provides a comprehensive review of the different types of steroids – androgens, oestrogens, and progestogens – that naturally occur in horses. It looks at their concentration ranges in different genders and factors that could potentially affect these levels. With this information, researchers may be more equipped to distinguish between natural and unnatural steroid presence, thus improving the detection and prevention of steroid use in horses.

Cite This Article

APA
Viljanto M, Gray B, Scarth J. (2023). Presence and detection of endogenous steroids in the horse-A review. Drug Test Anal. https://doi.org/10.1002/dta.3624

Publication

Drug testing and analysis
ISSN: 1942-7611
NlmUniqueID: 101483449
Country: England
Language: English

Researcher Affiliations

Viljanto, Marjaana
  • LGC, Cambridgeshire, UK.
Gray, Bobby
  • LGC, Cambridgeshire, UK.
Scarth, James
  • LGC, Cambridgeshire, UK.

References

This article includes 193 references
  1. Miller WL, Auchus RJ. The molecular biology, biochemistry and physiology of human steroidogenesis and its disorders.. Endocr Rev 2011;32(1):81-151.
    doi: 10.1210/er.2010-0013google scholar: lookup
  2. Payne AH, Hales DB. Overview of steroidogenic enzymes in the pathway from cholesterol to active steroid hormones.. Endocr Rev 2004;25(6):947-970.
    doi: 10.1210/er.2003-0030google scholar: lookup
  3. Nussay S, Whitehead S. Chapter 4: The adrenal gland.. In: Nussay S, Whitehead S, eds. Endocrinology: An Integrated Approach. BIOS Scientific Publishers Limited; 2001:115-168.
    doi: 10.4324/9780203450437_chapter_4google scholar: lookup
  4. Lemazurier E, Sourdaine P, Nativelle P, Plainfosse B, Seralini G-E. Aromatase gene expression in the stallion.. Mol Cell Endocrinol 2001;178(1-2):133-139.
    doi: 10.1016/s0303-7207(01)00435-xgoogle scholar: lookup
  5. Kicman AT. Pharmacology of anabolic steroids.. Br J Pharmacol 2008;154(3):502-521.
    doi: 10.1038/bjp.2008.165google scholar: lookup
  6. International Federation of Horseracing Authorities. 2022 International agreement on breeding, racing and wagering and appendixes. Accessed on 5 June 2023. https://www.ifhaonline.org/resources/ifAgreement.pdf
  7. World Anti-Doping Agency. 2023 Anti-doping testing figures report 2021. Accessed on 5 June 2023. https://www.wada-ama.org/sites/default/files/2023-01/2021_anti-doping_testing_figures_en.pdf
  8. Scarth J, McKinney A, Bailly-Chouriberry L. Analytical advances in horseracing medication and doping control from 2016 to 2018.. In: Baudot B, Cawley A, Howitt R, et al., eds. Proceedings of the 22nd International Conference of Racing Analysts and Veterinarians. Regent Press Co Ltd; 2018:74-88.
  9. Tang PW, Law WC, Crone DL. A urinary threshold for testosterone in geldings.. In: Auer DE, Houghton E, eds. Proceedings of the 11th International Conference of Racing Analysts and Veterinarians. R&W Publications; 1996:68-72.
  10. Fazio E, Medica P, Aronica V, Grasso L, Ferlazzo A. Circulating β-endorphin, adrenocorticotrophic hormone and cortisol levels of stallions before and after short road transport: stress effect of different distances.. Acta Vet Scand 2008;50(1):6.
    doi: 10.1186/1751-0147-50-6google scholar: lookup
  11. Ayala I, Martos NF, Silvan G, Gutierrez-Panizo C, Clavel JG, Illera JC. Cortisol, adrenocorticotropic hormone, serotonin, adrenaline and noradrenaline serum concentrations in relation to disease and stress in the horse.. Res Vet Sci 2012;93(1):103-107.
    doi: 10.1016/j.rvsc.2011.05.013google scholar: lookup
  12. Fidani M, Casagni E, Montana M, Pasello E, Pecoraro C, Gambaro V. Rapid test by liquid chromatography/tandem mass spectrometry to evaluate equine urine reactivity towards 17β-OH steroids.. Rapid Commun Mass Spectrom 2006;20(16):2441-2446.
    doi: 10.1002/rcm.2608google scholar: lookup
  13. Viljanto M, Kicman AT, Walker CJ. Bioformation of boldenone and related precursors/metabolites in equine feces and urine, with relevance to doping control.. Drug Test Anal 2019;12(2):215-229.
    doi: 10.1002/dta.2706google scholar: lookup
  14. Gray BP, Teale P, Pearce CM. Analysis of methyloxime derivatives of intact esters of testosterone and boldenone in equine plasma using ultra high performance liquid chromatography tandem mass spectrometry.. Drug Test Anal 2011;3(4):206-213.
    doi: 10.1002/dta.237google scholar: lookup
  15. Gray B, Viljanto M, Menzies E, Vanhaecke L. Detection of prohibited substances in equine hair by ultra-high performance liquid chromatography-triple quadrupole mass spectrometry - application to doping control samples.. Drug Test Anal 2018;10(7):1050-1060.
    doi: 10.1002/dta.2367google scholar: lookup
  16. Kaabia Z, Dervilly-Pinel G, Hanganu F. Ultra high performance liquid chromatography/tandem mass spectrometry based identification of steroid esters in serum and plasma: an efficient strategy to detect natural steroids abuse in breeding and racing animals.. J Chromatogr a 2013;1284:126-140.
    doi: 10.1016/j.chroma.2013.02.010google scholar: lookup
  17. Houghton E. Threshold values - current and future problems.. In: Kallings P, Bondesson U, Houghton E, eds. Proceedings of the 10th International Conference of Racing Analysts and Veterinarians. Stockholm; 1994:297-302.
  18. Bonnaire Y, Dehennin L, Plou P. The determination of a threshold value for testosterone: approached to the problem.. In: Auer DE, Houghton E, eds. Proceedings of the 11th International Conference of Racing Analysts and Veterinarians. R&W Publications; 1996:56-61.
  19. Viljanto M, Zied K, Taylor P. Differentiation of boldenone administration from ex vivo transformation in the urine of castrated male horses.. Drug Test Anal 2022;14(5):887-901.
    doi: 10.1002/dta.3240google scholar: lookup
  20. Viljanto M, Zied K, Taylor P. Detection of boldenone in the urine of female horses-ex vivo formation versus administration.. Drug Testing and Analysis 2023.
    doi: 10.1002/dta.3521google scholar: lookup
  21. Piper T, Mareck U, Geyer H. Determination of 13C/12C ratios of endogenous urinary steroids: method validation, reference population and application to doping control purposes.. Rapid Commun Mass Spectrom 2008;22(14):2161-2175.
    doi: 10.1002/rcm.3601google scholar: lookup
  22. World Anti-Doping Agency. 2021 Measurement and reporting of endogenous anabolic androgenic steroid (EAAS) markers of the urinary steroid profile. Accessed on 5 June 2023. https://www.wada-ama.org/sites/default/files/2022-01/td2021eaas_final_eng_v_2.0.pdf
  23. Kaabia Z. Investigation of Novel Analytical Strategies to Detect Natural Steroid Hormones Misuse in Bovine and Equine.. PhD thesis,. L'Université Nantes Angers Le Mans; 2013.
  24. Reichel C. OMICS-strategies and methods in the fight against doping.. Forensic Sci Int 2011;213(1-3):20-34.
    doi: 10.1016/j.forsciint.2011.07.031google scholar: lookup
  25. Cawley A, Keledjian J. Intelligence-based anti-doping from an equine biological passport.. Drug Test Anal 2017;9(9):1441-1447.
    doi: 10.1002/dta.2180google scholar: lookup
  26. Dirikolu L, Lehner AF. A review of current chemistry, pharmacology, and regulation of endogenous anabolic steroids testosterone, boldenone, and nandrolone in horses.. J Vet Pharmacol Ther 2023;46(4):201-217.
    doi: 10.1111/jvp.13397google scholar: lookup
  27. Strompen O, Opfermann G, Enbergs H, Schänzer W. Determination of endogenous steroid profiles in equine urine by gas chromatography/mass spectrometry.. In: Hill DW, Hill WT, eds. Proceedings of 14th International Conference of Racing Analysts and Veterinarians. R&W Publications; 2002:188-194.
  28. Decloedt A, Bailly-Chouriberry L, Vanden BJ. A validated UHPLC-MS/MS method to quantify low levels of anabolic-androgenic steroids naturally present in urine of untreated horses.. Anal Bioanal Chem 2015;407(15):4385-4396.
    doi: 10.1007/s00216-014-8428-xgoogle scholar: lookup
  29. Tang PW, Ip WC, Law WC, Wan TSM, Crone DL. Further studies on the testosterone threshold for geldings.. In: Laviolette B, Koupai-Abyazani MR, eds. Proceedings of the 12th International Conference of Racing Analysts and Veterinarians. R&W Publications; 1998:107-112.
  30. Viljanto M, Scarth J, Hincks P. Application of testosterone to epitestosterone ratio to horse urine-a complementary approach to detect the administration of testosterone and its pro-drugs in thoroughbred geldings.. Drug Test Anal 2017;9(9):1328-1336.
    doi: 10.1002/dta.2109google scholar: lookup
  31. Bonnaire Y, Dehennin L, Popot MA, Plou P. Testosterone in mares and fillies: a new threshold.. In: Auer DE, Houghton E, eds. Proceedings of the 13th International Conference of Racing Analysts and Veterinarians. R&W Publications; 2000:60-63.
  32. Bonnaire Y, Dehennin L, Plou P, Toutain PL. Testosterone administration to mares: criteria for detection of testosterone abuse by analysis of metabolites in plasma and urine.. J Anal Toxicol 1995;19(3):175-181.
    doi: 10.1093/jat/19.3.175google scholar: lookup
  33. Soma LR, Uboh CE, Guan F, McDonnell S. Plasma concentrations of testosterone and 19-nortestosterone (nandrolone) in the nonracing intact male horse by liquid chromatography-mass spectrometry.. J Vet Pharmacol Ther 2008;31(6):587-590.
    doi: 10.1111/j.1365-2885.2008.00997.xgoogle scholar: lookup
  34. Soma LR, Uboh CE, Guan F, McDonnell S, Pack J. Pharmacokinetics of boldenone and stanozolol and the results of quantification of anabolic and androgenic steroids in race horses and nonrace horses.. J Vet Pharmacol Ther 2007;30(2):101-108.
    doi: 10.1111/j.1365-2885.2007.00824.xgoogle scholar: lookup
  35. Ho ENM, Kwok WH, Leung DKK. Control of the misuse of testosterone in castrated horses based on an international threshold in plasma.. Drug Test Anal 2015;7(5):414-419.
    doi: 10.1002/dta.1681google scholar: lookup
  36. Popot MA, Stojilkovic N, Allard F. Quantification of testosterone in female plasma: a German and French combined study. Contribution to the determination of a threshold value.. In: Baudot B, Gordon Gntil C, Howitt R, Knight P, Symons P, eds. Proceedings of the 20th International Conference of Racing Analysts and Veterinarians. Regent Press Co Ltd; 2014:542-546.
  37. Viljanto M, Popot M-A, Schenk I. International population study of free-testosterone concentrations in plasma samples from fillies.. In: Houghton E, Symons P, Knight P, Sams R, Wynne P, Gordon GC, eds. Proceedings of the 21st International Conference of Racing Analysts and Veterinarians, Uruguay. Regent Press Co Ltd; 2016:82-87.
  38. Bedrak E, Samuels LT. Steroid biosynthesis by the equine testis.. Endocrinology 1969;85(6):1186-1195.
    doi: 10.1210/endo-85-6-1186google scholar: lookup
  39. Houghton E, Dumasia MC, Teale P. The use of stable isotopes and gas chromatography/mass spectrometry in the identification of steroid metabolites in the equine.. Steroids 1990;55(10):433-439.
    doi: 10.1016/0039-128x(90)90011-ygoogle scholar: lookup
  40. Silberzahn P, Zwain I, Guerin P, Benoit E, Jouany JM, Bonnaire Y. Testosterone response to human chorionic gonadotrophin injection in the stallion.. Equine Vet J 1988;20(1):61-63.
    doi: 10.1111/j.2042-3306.1988.tb01456.xgoogle scholar: lookup
  41. Silberzahn P, Dehennin L, Zwain I, Leymarie P. Identification and measurement of testosterone in plasma and follicular fluid of the mare, using gas chromatography-mass spectrometry associated with isotope dilution.. Endocrinology 1983;97(1):51-56.
    doi: 10.1677/joe.0.0970051google scholar: lookup
  42. Silberzahn P, Rashed F, Zwain I, Leymarie P. Androstenedione and testosterone biosynthesis by the adrenal cortex of the horse.. Steroids 1984;43(2):147-152.
    doi: 10.1016/0039-128x(84)90033-3google scholar: lookup
  43. Houghton E, Ginn A, Teale P, Dumasia MC, Grainger L. ACTH administration to the gelding: effect on urinary androgens.. In: Tobin T, Blake J, Potter M, Wood T, eds. Proceedings of the 7th International Conference of Racing Analysts and Veterinarians. University of Kentucky; 1988:507-511.
  44. Popot MA, Garcia P, Dehennin L. ACTH administration and detection in the horse.. In: Laviolette B, Koupai-Abyazani MR, eds. Proceedings of the 12th International Conference of Racing Analysts and Veterinarians. R&W Communication. Newmarket; 1998:131-138.
  45. Dumasia MC, Houghton E. Studies related to the metabolism of anabolic steroids in the horse: the identification of some 16-oxygenated metabolites of testosterone and a study of the phase II metabolism.. Xenobiotica 1981;11(5):323-331.
    doi: 10.3109/00498258109045311google scholar: lookup
  46. Anielski P, Thieme D, Schlupp A, Grosse J, Ellendorff F, Mueller RK. Detection of testosterone, nandrolone and precursors in horse hair.. Anal Bioanal Chem 2005;383(6):903-908.
    doi: 10.1007/s00216-005-0104-8google scholar: lookup
  47. Houghton E, Dumasia MC. Studies related to the metabolism of anabolic steroids in the horse: testosterone.. Xenobiotica 1979;9(5):269-279.
    doi: 10.3109/00498257909038730google scholar: lookup
  48. Dumasia MC, Houghton E, Sinkins S. Development of a gas chromatographic-mass spectrometric method using multiple analytes for the confirmatory analysis of anabolic steroids in horse urine: I. Detection of testosterone phenylpropionate administrations to equine male castrates.. J Chromatogr B Biomed Sci Appl 1986;377:23-33.
    doi: 10.1016/s0378-4347(00)80758-6google scholar: lookup
  49. Wong JKY, Leung DKK, Curl P, Schiff PJ, Lam KKH, Wan TSM. Evidence of boldenone, nandrolone, 5(10)-estrene-3β,17β-diol and 4-estrene-3,17-dione as minor metabolites of testosterone in equine.. Drug Test Anal 2017;9(9):1337-1348.
    doi: 10.1002/dta.2192google scholar: lookup
  50. Smith SJ, Cox JE, Houghton E, Dumasia MC, Moss MS. In vitro biosynthesis of C18 neutral steroids in horse testes.. J Reprod Fertil Suppl 1987;35:71-78.
  51. Dumasia MC, Houghton E, Jackie M. Steroids in equine testes: the identification of endogenous 19-hydroxy and 19-nor neutral steroids by gas chromatography-mass spectrometry.. J Endocrinol 1989;120(2):223-229.
    doi: 10.1677/joe.0.1200223google scholar: lookup
  52. Silberzahn P, Dehennin L, Zwain I, Reiffsteck A. Gas chromatography-mass spectrometry of androgens in equine ovarian follicles at ultrastructurally defined stages of development. Identification of 19-nortestosterone in follicular fluid.. Endocrinology 1985;117(5):2176-2181.
    doi: 10.1210/endo-117-5-2176google scholar: lookup
  53. Houghton E, Teale P, Fenyvesi I, Dumasia MC. Studies related to the origin of C18 neutral steroids isolated from extracts of urine from the entire male horse.. In: Albert PH, Morton T, Wade JF, eds. Proceedings of the 15th International Conference of Racing Analysts and Veterinarians. R & W Publications; 2004:161-166.
  54. Houghton E, Teale P, Dumasia M. Studies related to the origin of C18 neutral steroids isolated from extracts of urine from the male horse: The identification of urinary 19-oic acids and their decarboxylation to produce estr-4-en-17β-ol-3-one (19-nortestosterone) and estr-4-ene-3,17-dione (19-norandrost-4-ene-3,17-dione) during sample processing.. Anal Chim Acta 2007;586(1-2):196-207.
    doi: 10.1016/j.aca.2006.11.059google scholar: lookup
  55. Guan F, Uboh CE, Soma LR, You Y, Li X, McDonnell S. Ex vivo spontaneous generation of 19-norandrostenedione and nandrolone detected in equine plasma and urine.. J Steroid Biochem Mol Biol 2012;128(1-2):1-11.
    doi: 10.1016/j.jsbmb.2011.10.005google scholar: lookup
  56. McKinney AR, Pu F, McLeod MD, Suann CJ, Stenhouse AM. 17β-hydroxy-3-oxoandrost-4-en-19-oic acid as a source of nandrolone in acid solvolyzed stallion urine extracts.. In: Houghton E, Kijima-Suda I, Wada R, Wade JF, eds. Proceedings of 16h International Conference of Racing Analysts and Veterinarians. R&W Publications; 2006:84-89.
  57. Teale P, Houghton E. Metabolism of anabolic steroids and their relevance to drug detection in horseracing.. Bioanalysis 2010;2(6):1085-1107.
    doi: 10.4155/bio.10.57google scholar: lookup
  58. Dumasia MC, Houghton E. Studies related to the metabolism of anabolic steroids in the horse: the phase I and phase II biotransformation of 19-nortestosterone in the equine castrate.. Xenobiotica 1984;14(8):647-655.
    doi: 10.3109/00498258409151462google scholar: lookup
  59. Grace PB, Drake EC, Teale P, Houghton E. Quantification of 19-nortestosterone sulphate and boldenone sulphate in urine from male horses using liquid chromatography/tandem mass spectrometry.. Rapid Commun Mass Spectrom 2008;22(19):2999-3007.
    doi: 10.1002/rcm.3698google scholar: lookup
  60. Houghton E. Studies related to the metabolism of anabolic steroids in the horse: 19-nortestosterone.. Xenobiotica 1977;7(11):683-693.
    doi: 10.3109/00498257709038698google scholar: lookup
  61. Houghton E, Dumasia MC. Studies related to the metabolism of anabolic steroids in the horse: the identification of some 16-oxygenated metabolites of 19-nortestosterone.. Xenobiotica 1980;10(5):381-390.
    doi: 10.3109/00498258009033771google scholar: lookup
  62. Houghton E, Copsey J, Dumasia MC, Haywood PE, Moss MS, Teale P. The identification of C-18 neutral steroids in normal stallion urine.. Biomed Mass Spectrom 1984;11(2):96-99.
    doi: 10.1002/bms.1200110209google scholar: lookup
  63. Roig M, Segura J, Ventura R. Quantification of 17β-nandrolone metabolites in boar and horse urine by gas chromatography-mass spectrometry.. Anal Chim Acta 2007;586(1-2):184-195.
    doi: 10.1016/j.aca.2006.08.033google scholar: lookup
  64. Ho ENM, Yiu KCH, Tang FPW. Detection of endogenous boldenone in the entire male horses.. J Chromatogr B 2004;808(2):287-294.
    doi: 10.1016/j.jchromb.2004.05.018google scholar: lookup
  65. Dehennin L, Bonnaire Y, Plou P, Ho ENM, Yiu KCH, Wan TSM. Urinary excretion of endogenous boldenone by entire male horses: identification and quantification by gas chromatography-mass spectrometry.. In: Hill DW, Hill WT, eds. Proceedings of 14th International Conference of Racing Analysts and Veterinarians. R&W Publications; 2002:58-64.
  66. Viljanto M, Kicman AT, Walker CJ. Elucidation of the biosynthetic pathways of boldenone in the equine testis.. Steroids 2019;146:79-91.
    doi: 10.1016/j.steroids.2019.03.011google scholar: lookup
  67. Bailly-Chouriberry L, Thiebaud G, Garcia P. Boldenone positive cases associated to altered black oats.. In: Houghton E, Symons P, Knight P, Sams R, Wynne P, Gordon GC, eds. Proceedings of the 21st International Conference of Racing Analysts and Veterinarians. Regent Press Co Ltd; 2016:75-81.
  68. Huang C-L, Chen Y-R, Liu W-H. Production of androstenones from phytosterols by mutants of Mycobacterium sp.. Enzyme Microb Technol 2006;39(2):296-300.
    doi: 10.1016/j.enzmictec.2005.10.017google scholar: lookup
  69. Verheyden K, Noppe H, Zorn H. Endogenous boldenone-formation in cattle: alternative invertebrate organisms to elucidate the enzymatic pathway and the potential role of edible fungi on cattle's feed.. J Steroid Biochem 2010;119(3-5):161-170.
    doi: 10.1016/j.jsbmb.2010.02.020google scholar: lookup
  70. Schänzer W, Geyer H, Gotzmann A. Endogenous production and excretion of boldenone (17beta-hydroxyandrosta-1,4-dien-3-one), an androgenic anabolic steroid.. In: Donike M, Geyer H, Gotzmann A, Mareck-Engelke U, eds. Proceedings of the 12th Cologne Workshop on Dope Analysis. Recent Advances in Doping Analysis. Sport and Buch Strauß; 1994:211.
  71. Fidani M, Gamberini MC, Pasello F. Evaluation of equine urine reactivity towards phase II metabolites of 17-hydroxy steroids by liquid chromatography/tandem mass spectrometry.. Rapid Commun Mass Spectrom 2009;23(1):65-76.
    doi: 10.1002/rcm.3858google scholar: lookup
  72. Van de Kerkhof DH, van der Voort PM, de Boer D, Maes RAA. Confirmation of endogenous boldenone production: a procedure for an in vitro experiment.. In: Schänzer W, Geyer H, Gotzmann A, Mareck-Engelke U, eds. Proceedings of the 17th Cologne Workshop on Dope Analysis. Recent Advances in Doping Analysis. Sport and Buch Strauß; 1999:161-168.
  73. Pompa G, Arioli F, Fracchiolla ML. Neoformation of boldenone and related steroids in faeces of veal calves.. Food Addit Contam 2006;23(2):126-132.
    doi: 10.1080/02652030500442508google scholar: lookup
  74. Dumasia MC, Houghton E, Bradley CV, Williams DH. Studies related to metabolism of anabolic steroids in the horse: the metabolism of 1-dehydrotestosterone and the use of fast atom bombardment mass spectrometry in the identification of steroid conjugates.. Biomed Mass Spectrom 1983;10(7):434-440.
    doi: 10.1002/bms.1200100709google scholar: lookup
  75. Pu F, McKinney AR, Stenhouse AM, Suann CJ, McLeod MD. Direct detection of boldenone sulfate and glucuronide conjugates in horse urine by ion trap liquid chromatography-mass spectrometry.. J Chromatogr B 2004;813(1-2):241-246.
    doi: 10.1016/j.jchromb.2004.09.052google scholar: lookup
  76. Dumasia MC, Houghton E. Biotransformation of 1-dehydrotestosterone in the equine male castrate: identification of the neutral unconjugated and glucuronic acid conjugated metabolites in horse urine.. Biomed Environ Mass Spectrom 1988;17(5):373-392.
    doi: 10.1002/bms.1200170507google scholar: lookup
  77. Jouany J-M, Bonnaire Y, Plou P, Silberzahn P, Boudene C. Metabolic profiles of anabolic steroids in racehorse urine.. In: Crone DL, ed. Proceedings of the 6th International Conference of Racing Analysts and Veterinarians. McMillan Publishers; 1985:233-239.
  78. Viljanto M, Hincks P, Hillyer L. Monitoring dehydroepiandrosterone (DHEA) in the urine of thoroughbred geldings for doping control purposes.. Drug Test Anal 2018;10(10):1518-1527.
    doi: 10.1002/dta.2411google scholar: lookup
  79. Fragkaki AG, Angelis YS, Koupparis M, Tsantili-Kakoulidou A, Kokotos G, Georgakopoulos C. Structural characteristics of anabolic androgenic steroids contributing to binding to the androgen receptor and to their anabolic and androgenic activities: applied modifications in the steroidal structure.. Steroids 2009;74(2):172-197.
    doi: 10.1016/j.steroids.2008.10.016google scholar: lookup
  80. Fang H, Tong W, Branham WS. Study of 202 natural, synthetic and environmental chemicals for binding to the androgen receptor.. Chem Res Toxicol 2003;16(10):1338-1358.
    doi: 10.1021/tx030011ggoogle scholar: lookup
  81. Pereira de Jesus-Tran K, Cote P-L, Cantin L, Blanchet J, Labrie F, Breton R. Comparison of crystal structures of human androgen receptor ligand-binding domain complexed with various agonists reveals molecular determinants responsible for binding affinity.. Protein Sci 2009;15(5):987-999.
  82. Dehennin L, Bonnaire Y, Plou P. Human nutritional supplements in the horse. Dehydroepiandrosterone versus androstenedione: comparative effects on the androgen profile and consequences for doping analysis.. J Anal Toxicol 2001;25(8):685-690.
    doi: 10.1093/jat/25.8.685google scholar: lookup
  83. Kicman AT, Houghton E, Gower DB. Anabolic steroids: metabolism, doping and detection in human and equestrian sports.. In: Makin HLJ, Gower DB, eds. Steroid Analysis. 2nd ed. Springer; 2010:743-836.
    doi: 10.1023/b135931_9google scholar: lookup
  84. Genangeli M, Caprioli G, Cortese M. Development and application of a UHPLC-MS/MS method for simultaneous determination of 17 steroidal hormones in equine serum.. J Mass Spectrom 2017;52(1):22-29.
    doi: 10.1002/jms.3896google scholar: lookup
  85. Dehennin L, Bonnaire Y, Plou P. Detection of nandrolone administration to the entire male horse by a provisional concentration threshold for urinary oestranediol determined by gas chromatography-mass spectrometry.. Equine Vet J 2007;39(2):186-188.
    doi: 10.2746/042516407x170418google scholar: lookup
  86. Bollwein H, Schulze JJ, Miyamoto A, Sieme H. Testicular blood flow and plasma concentrations of testosterone and total estrogen in the stallion after the administration of human chorionic gonadotrophin.. J Reprod Dev 2008;54(5):335-339.
    doi: 10.1262/jrd.20014google scholar: lookup
  87. Dintinger T, Gaillard J-L, Zwain I, Bouhamidi R, Silberzahn P. Synthesis and aromatization of 19-norandrogens in the stallion testis.. J Steroid Biochem 1989;32(4):537-544.
    doi: 10.1016/0022-4731(89)90387-7google scholar: lookup
  88. Silberzahn P, Gaillard JL, Quincey D, Dintinger T, Al-Timimi I. Aromatization of testosterone and 19-nortestosterone by a single enzyme from equine testicular microsomes. Differences from human placental aromatase.. J Steroid Biochem 1988;29(1):119-125.
    doi: 10.1016/0022-4731(88)90385-8google scholar: lookup
  89. Moslemi S, Vibet A, Papadopoulos V, Camoin L, Silberzahn P, Gaillard J-L. Purification and characterization of equine testicular cytochrome P-450 aromatase: comparison with the human enzyme.. Comparative Biochem Physiol Part B: Biochem Molec Biol 1997;118(1):217-227.
    doi: 10.1016/s0305-0491(97)00033-3google scholar: lookup
  90. Dintinger T, Gaillard JL, Moslemi S, Zwain I, Silberzahn P. Androgen and 19-norandrogen aromatization by equine and human placental microsomes.. J Steroid Biochem 1989;33(5):949-954.
    doi: 10.1016/0022-4731(89)90245-8google scholar: lookup
  91. Holtan DW, Houghton E, Silver M, Fowden AL, Ousey J, Rossdale PD. Plasma progestogens in the mare, fetus and newborn foal.. J Reprod Fertil Suppl 1991;44:517-528.
  92. Kuhl H. Pharmacology of estrogens and progestogens: influence of different routes of administration.. Climacteric 2005;8(supplement 1):3-63.
    doi: 10.1080/13697130500148875google scholar: lookup
  93. Hamon M, Clarke SW, Houghton E. Production of 5 alpha-dihydroprogesterone during late pregnancy in the mare.. J Reprod Fertil Suppl 1991;44:529-535.
  94. Ousey JC, Houghton E, Grainger L, Rossdale P, Fowden A. Progestagen profiles during the last trimester of gestation in thoroughbred mares with normal or compromised pregnancies.. Theriogenology 2005;63(7):1844-1856.
    doi: 10.1016/j.theriogenology.2004.08.010google scholar: lookup
  95. Legacki EL, Scholtz EL, Ball BA, Stanley SD, Berger T, Conley AJ. The dynamic steroid landscape of equine pregnancy mapped by mass spectrometry.. Reproduction 2016;151(4):421-430.
    doi: 10.1530/rep-15-0547google scholar: lookup
  96. Mueller POE, Parks AH. Cryptorchidism in horses.. Equine Vet J 1999;11(2):77-86.
    doi: 10.1111/j.2042-3292.1999.tb00926.xgoogle scholar: lookup
  97. Leung DKK, Tang FPW, Wan TSM, Wong JKY. Identification of cryptorchidism in horses by analysing urine samples with gas chromatography/mass spectrometry.. Vet J 2011;187(1):60-64.
    doi: 10.1016/j.tvjl.2009.10.010google scholar: lookup
  98. Dehennin L, Petit E, Bonnaire Y, Bruyas JF, Le Bizec B, Plou P. Urinary excretion of 5(10)-estrene-3β,17α-diol and estrone by the female horse: complementary indicators of early pregnancy screened with regard to a putative anabolic doping practice.. J Steroid Biochem Mol Biol 2007;104(1-2):85-91.
    doi: 10.1016/j.jsbmb.2006.10.005google scholar: lookup
  99. Ousey JC, Forehead AJ, Rossdale PD, Grainger L, Houghton E, Fowden AL. Ontogeny of uteroplacental progestogen production in pregnant mares during the second half of gestation.. Biol Reprod 2003;69(2):540-548.
    doi: 10.1095/biolreprod.102.013292google scholar: lookup
  100. Houghton E, Holtan D, Grainger L, Voller BE, Rossdale PD, Ousey JC. Plasma progestogen concentrations in the normal and dysmature newborn foal.. J Reprod Fertil 1991;44:609-617.
  101. Aleman M, McCue PM, Chigerwe M, Madigan JE. Plasma concentrations of steroid precursors, steroids, neuroactive steroids, and neurosteroids in healthy neonatal foals from birth to 7 days of age.. J Vet Intern Med 2019;33(5):2286-2293.
    doi: 10.1111/jvim.15618google scholar: lookup
  102. Legacki EL, Scholtz EL, Ball BA, Esteller-Vico A, Stanley SD, Conley AJ. Concentrations of sulphated estrone, estradiol and dehydroepiandrosterone measured by mass spectrometry in pregnant mares.. Equine Vet J 2019;51(6):802-808.
    doi: 10.1111/evj.13109google scholar: lookup
  103. Sterk S, Herbold H, Blokland M, Van Rossum H, Van Ginkel LA, Stephany R. Nortestosterone: endogenous in urine of goats, sheep and mares?. Analyst 1998;123(12):2633-2636.
    doi: 10.1039/a804947egoogle scholar: lookup
  104. Kirkpatrick JF, Vail R, Devous S, Schwend S, Baker CB, Wiesner L. Diurnal variation of plasma testosterone in wild stallions.. Biol Reprod 1976;15(1):98-101.
    doi: 10.1095/biolreprod15.1.98google scholar: lookup
  105. Sharma OP. Diurnal variations of plasma testosterone in stallions.. Biol Reprod 1976;15(2):158-162.
    doi: 10.1095/biolreprod15.2.158google scholar: lookup
  106. Ginther OJ, Utt MD, Beg MA. Follicle deviation and diurnal variation in circulating hormone concentrations in mares.. Anim Reprod Sci 2007;100(1-2):197-203.
    doi: 10.1016/j.anireprosci.2006.08.025google scholar: lookup
  107. Bono G, Minori D, Gaiani R, Mattioli M. Concentrations of oestrone sulphate, androgens and LH in the peripherial plasma of mating stallions.. J Reprod Fertil 1982;66(1):17-22.
    doi: 10.1530/jrf.0.0660017google scholar: lookup
  108. Kirkpatrick JF, Wiesner L, Kenney RM, Ganjam VK, Turner JW. Seasonal variation in plasma androgens and testosterone in north American wild horse.. J Endocrinol 1977;72(2):237-238.
    doi: 10.1677/joe.0.0720237google scholar: lookup
  109. Raeside JI. Seasonal changes in the concentrations of estrogens and testosterone in the plasma of the stallion.. Anim Reprod Sci 1979;1(3):205-212.
    doi: 10.1016/0378-4320(79)90002-2google scholar: lookup
  110. Donadeu FX, Watson ED. Seasonal changes in ovarian activity: lessons learnt from the horse.. Anim Reprod Sci 2007;100(3-4):225-242.
    doi: 10.1016/j.anireprosci.2006.12.001google scholar: lookup
  111. James VHT, Horner MW, Moss MS, Rippon AE. Adrenocortical function in the horse.. J Endocrinol 1970;48(3):319-335.
    doi: 10.1677/joe.0.0480319google scholar: lookup
  112. Stull CL, Rodiek AV. Physiological responses of horses to 24 hours of transportation using a commercial van during summer conditions.. J Anim Sci 2000;78(6):1458-1466.
    doi: 10.2527/2000.7861458xgoogle scholar: lookup
  113. Schmidt A, Biau S, Mostl E. Changes in cortisol release and heart rate variability in sport horses during long-distance road transport.. Domest Anim Endocrinol 2010;38(3):179-189.
    doi: 10.1016/j.domaniend.2009.10.002google scholar: lookup
  114. Viljanto M. Novel approaches to detection of the use of pseudo-endogenous anabolic-androgenic steroids in the horse.. PhD thesis,. King's College London; 2019.
  115. Fazio E, Medic P, Cravana C, Ferlazzo A. Effects of competition experience and transportation on the adrenocorticortical and thyroid responses of horses.. Vet Rec 2008;163(24):713-716.
    doi: 10.1136/vr.163.24.713google scholar: lookup
  116. Toutain PL, Lassourd V, Popot MA, Laroute V, Alvinerie M, Bonnaire Y. Urinary cortisol excretion in the resting and exercising horse.. Equine Vet J 1995;27(S18):457-462.
    doi: 10.1111/j.2042-3306.1995.tb04973.xgoogle scholar: lookup
  117. Golland LC, Evans DL, Stone GM, Tyler-McGowan CM, Hodgson DR, Rose RJ. Maximal exercise transiently disrupts hormonal secretory patterns in standardbred geldings.. Equine Vet J Suppl 1999;30(S30):581-585.
    doi: 10.1111/j.2042-3306.1999.tb05288.xgoogle scholar: lookup
  118. Hurcombe SDA, Toribio RE, Slovis N. Blood arginine vasopressin, adrenocorticotropin hormone and cortisol concentrations at admission in septic and critically ill foals and their association with survival.. J Vet Intern Med 2008;22(3):639-647.
    doi: 10.1111/j.1939-1676.2008.0090.xgoogle scholar: lookup
  119. Mair TS, Sherlock CE, Boden LA. Serum cortisol concentrations in horses with colic.. Vet J 2014;201(3):370-377.
    doi: 10.1016/j.tvjl.2014.06.005google scholar: lookup
  120. Kennedy DG, Shortt HD, Crooks SRH. Occurrence of α- and β-nortestosterone residues in the urine of injured male cattle.. Food Additives Contaminants: Part a 2009;26(5):683-691.
    doi: 10.1080/02652030802662738google scholar: lookup
  121. Stabenfeldt GH, Hughes JP, Kennedy PC, Meagher DM, Neely DP. Clinical findings, pathological changes and endocrinological secretory patterns in mares with ovarian tumours.. J Reprod Fertil Suppl 1979;27:277-285.
  122. McCue PM, Roser JF, Munro CJ, Liu IKM, Lasley BL. Granulosa cell tumors of the equine ovary.. Vet Clin Equine 2006;22(3):799-817.
    doi: 10.1016/j.cveq.2006.08.008google scholar: lookup
  123. Van der Kolk JH, Kalsbeek HC, Wensing T, Breukink HJ. Urinary concentration of corticoids in normal horses and horses with hyperadrenocorticism.. Res Vet Sci 1994;56(1):126-128.
    doi: 10.1016/0034-5288(94)90210-0google scholar: lookup
  124. Couëtil L, Paradis MR, Knoll J. Plasma adrenocorticotropin concentration in healthy horses and in horses with clinical signs of hyperadrenocorticism.. J Vet Intern Med 1996;10(1):1-6.
    doi: 10.1111/j.1939-1676.1996.tb02016.xgoogle scholar: lookup
  125. Mathur S, Bhatia MC, Mathur SN. Biotransformation of β-sitosterol into 17-ketosteroids by some strains of Arthrobacter.. Role Biotechnol Agricult 1992;99-102.
  126. Decloedt A, Bailly-Chouriberry L, Vanden BJ. In vitro digestion simulation of the equine hindgut as a tool to study the influence of phytosterol consumption on the excretion of anabolic-androgenic steroids in horses.. J Steroid Biochem 2015;151:180-192.
    doi: 10.1016/j.jsbmb.2015.06.001google scholar: lookup
  127. Lo CK, Pan CP, Liu WH. Production of testosterone from phytosterol using a single-step microbial transformation by a mutant of Mycobacterium sp.. J Ind Microbiol Biotechnol 2002;28(5):280-283.
    doi: 10.1038/sj.jim.7000243google scholar: lookup
  128. Decloedt AI, Bailly-Chouriberry L, Vanden BJ. Mouldy feed: a possible explanation for the excretion of anabolic-androgenic steroids in horses.. Drug Test Anal 2016;8(5-6):525-534.
    doi: 10.1002/dta.2023google scholar: lookup
  129. Mösseler A, Licht S, Wilhelm L, Kamphues J. Can oral intake of gamma-oryzanol (experimentally given orally as pure substance) result in doping relevant testosterone levels in the urine of mares and geldings?. In: Ellis AD, Longland AC, Coenen M, Miraglia N, eds. The Impact of Nutrition on the Health and Welfare of Horses: 5th European Workshop Equine Nutrition. Cirencester; 2010:293-295.
  130. Gambelunghe C, Rossi R, Sommavilla M. Effects of chrysin on urinary testosterone levels in human males.. J Med Food 2003;6(4):387-390.
    doi: 10.1089/109662003772519967google scholar: lookup
  131. Wein S, Wolffram S. Oral bioavailability of quercetin in horses.. J Equine Vet 2013;33(6):441-445.
    doi: 10.1016/j.jevs.2012.07.008google scholar: lookup
  132. Sticker LS, Thompson DL, Gentry LR. Pituitary hormone and insulin responses to infusion of amino acids and N-methyl-d,l-aspartate in horses.. J Anim Sci 2001;79(3):735-744.
    doi: 10.2527/2001.793735xgoogle scholar: lookup
  133. Estienne MJ, Broughton DS, Barb CR. Serum concentrations of luteinizing hormone, growth hormone, testosterone, estradiol and leptin in boars treated with N-methyl-d,l-aspartate.. J Anim Sci 2000;78(2):365-370.
    doi: 10.2527/2000.782365xgoogle scholar: lookup
  134. Stull CL, Rodiek AV. Responses of blood glucose, insulin and cortisol concentrations to common equine diets.. J Nutr 1987;118(2):206-213.
    doi: 10.1093/jn/118.2.206google scholar: lookup
  135. Moeller BC, Sams RA, Guinjab-Cagmat J, Szabo NJ, Colahan P, Stanley SD. An interlaboratory study of the pharmacokinetics of testosterone following intramuscular administration to thoroughbred horses.. J Vet Pharmacol Ther 2011;34(6):588-593.
    doi: 10.1111/j.1365-2885.2011.01277.xgoogle scholar: lookup
  136. Knych HM, Arthur RD, Stanley S, Mckemie D. Disposition and metabolic profile of the weak androgen dehydroepiandrosterone (DHEA) following administration as part of a nutritional supplement to exercised horses.. Drug Test Anal 2014;7(10):39-47.
  137. Dehennin L, Bonnaire Y, Plou P. Human nutritional supplements in the horse. Comparative effects of 19-norandrostenedione and 19-norandrostenediol on the 19-norsteroid profile and consequences for doping control.. J Chromatogr B 2002;766(2):257-263.
    doi: 10.1016/s0378-4347(01)00506-0google scholar: lookup
  138. Kim JY, Choi MH, Kim SJ, Chung BC. Measurement of 19-nortestosterone and its esters in equine plasma by high-performance liquid chromatography with tandem mass spectrometry.. Rapid Commun Mass Spectrom 2000;14(19):1835-1840.
    doi: 10.1002/1097-0231(20001015)14:19<1835::aid-rcm103>3.0.co;2-igoogle scholar: lookup
  139. Ginn A, Houghton E, Cowan DA. Testosterone and hCG administration: approaches to the problem.. In: Rodgers JP, Toms T, eds. Proceedings of the 8th International Conference of Racing Analysts and Veterinarians. The Jockey Club of Southern Africa; 1990:147-156.
  140. Cox JE, Williams JH, Rowe PH, Smith JA. Testosterone in normal, cryptorchid and castrated male horses.. Equine Vet J 1973;5(2):85-90.
    doi: 10.1111/j.2042-3306.1973.tb03200.xgoogle scholar: lookup
  141. Cox JE, Redhead PH. Prolonged effect of a single injection of human chorionic gonadotrophin on plasma testosterone and oestrone sulphate concentrations in mature stallions.. Equine Vet J 1990;22(1):36-38.
    doi: 10.1111/j.2042-3306.1990.tb04202.xgoogle scholar: lookup
  142. Brown-Douglas CG, Firth EC, Parkinson TJ, Fennessy PF. LH and testosterone responses to five doses of a GnRH analogue (buserelin acetate) in 12-month-old thoroughbred colts.. Theriogenology 2004;61(6):1051-1060.
    doi: 10.1016/j.theriogenology.2003.05.003google scholar: lookup
  143. Ghigo E, Arvat E, Ramunni J. Adrenocorticotropin- and cortisol-releasing effect of hexarelin, a synthetic growth hormone-releasing peptide, in normal subjects and patients with Cushing's syndrome.. J Clin Endocrinol Metabol 1997;82(8):2439-2444.
  144. Kennedy SR, Thompson DL Jr, Pruett HE, Bruns PJ, Deghenghi R. Growth hormone response to a novel growth hormone-releasing tripeptide in horses: interaction with gonadotrophin-releasing hormone, thyrotropin-releasing hormone and sulpiride.. Am Soc Anim Sci 2002;80(3):744-750.
    doi: 10.2527/2002.803744xgoogle scholar: lookup
  145. Decloedt A, Damen S, Vanhaecke L. Revealing the influence of glucocorticoid treatment on the excretion of anabolic-androgenic steroids in horses through in vitro digestive simulations and an in vivo case study.. Res Vet Sci 2017;115:132-137.
    doi: 10.1016/j.rvsc.2017.02.024google scholar: lookup
  146. Thevis M, Geyer H, Mareck U, Flenker U, Schänzer W. Doping-control analysis of the 5-alpha-reductase inhibitor finasteride: determination of its influence on urinary steroid profiles and detection of its major urinary metabolite.. Ther Drug Monit 2007;29(2):236-247.
    doi: 10.1097/ftd.0b013e31803bb85dgoogle scholar: lookup
  147. Kwok WH, Leung GNW, Wan TSM, Curl P, Schiff PJ. Metabolic study of androsta-1,4,6-triene-3,17-dione in horses using liquid chromatography/high resolution mass spectrometry.. J Steroid Biochem Mol Biol 2015a;152:142-154.
    doi: 10.1016/j.jsbmb.2015.05.011google scholar: lookup
  148. Leung GNW, Kwok WH, Wan TSM, Lam KKH, Schigg PJ. Metabolic studies of formestane in horses.. Drug Test Anal 2013;5(6):412-419.
    doi: 10.1002/dta.1444google scholar: lookup
  149. Leung GNW, Tang FPW, Wan TSM, Wong CHF, Lam KKH, Stewart BD. In vitro and in vivo studies of androst-4-ene-3,16,17-trione in horses by gas chromatography-mass spectrometry.. Biomed Chromatogr 2009;24(7):744-751.
  150. MacLeay JM, Kohn CW. Results of quantitative cultures of urine by free catch and catheterization from healthy adult horses.. J Vet Intern Med 1998;12(2):76-78.
    doi: 10.1111/j.1939-1676.1998.tb02098.xgoogle scholar: lookup
  151. Hansen W, Yourassowsky E. Detection of beta-glucuronidase in lactose-fermenting members of the family Enterobacteriaceae and its presence in bacterial urine cultures.. J Med Microbiol 1984;20(6):1177-1179.
    doi: 10.1128/jcm.20.6.1177-1179.1984google scholar: lookup
  152. Hawksworth G, Drasar BS, Hili MJ. Intestinal bacteria and the hydrolysis of glycosidic bonds.. J Med Microbiol 1971;4(4):451-459.
    doi: 10.1099/00222615-4-4-451google scholar: lookup
  153. Levy HR, Talalay P. Bacterial oxidation of steroids. II studies on the enzymatic mechanism of ring a dehydrogenation.. J Biol Chem 1959;234(8):2014-2021.
  154. Marcus PI, Talalay P. Induction and purification of alpha- and beta-hydroxysteroid dehydrogenases.. J Biol Chem 1956;218(2):661-674.
    doi: 10.1016/s0021-9258(18)65833-8google scholar: lookup
  155. Talalay P, Marcus PI. Specificity, kinetics, and inhibition of alpha- and beta-hydroxysteroid dehydrogenases.. J Biol Chem 1956;218:675-691.
  156. Talalay P, Wang VS. Enzymic isomerization of Δ5-3-ketosteroids.. Biochim Biophys Acta 1955;18(2):300-301.
    doi: 10.1016/0006-3002(55)90079-2google scholar: lookup
  157. Arioli F, Gavinelli MP, Fracchiolla ML. Evaluation of boldenone formation and related steroid transformations in veal faeces by liquid chromatography/tandem mass spectrometry.. Rapid Commun Mass Spectrom 2008;22(2):217-223.
    doi: 10.1002/rcm.3361google scholar: lookup
  158. Popot MA, Boyer S, Menaut L, Garcia P, Bonnaire Y, Lesage D. Boldenone, testosterone and 1,4-androstadiene-3,17-dione determination in faeces from horses, untreated and after administration of androstenedione-1,4-diene-3,17-dione (boldione).. Biomed Chromatogr 2008;22(6):662-670.
    doi: 10.1002/bmc.985google scholar: lookup
  159. Houghton E, Crone DL. The approaches adopted by the racing industry to address endogenous substances and substances of dietary origin.. In: Auer DE, Houghton E, eds. Proceedings of the 13th International Conference of Racing Analysts and Veterinarians. R&W Publications; 2000:23-28.
  160. The Association of Racing Commissioners International. 2023 Model rules of racing. Accessed on 18 October 2023. https://www.arci.com/wp-content/uploads/2023/07/MASTER-MODEL-RULES-VERSION-12.1.2-7-21-2023.pdf
  161. Houghton E, Ginn A. Nandrolone in the colt: a review of the science relating to the threshold value.. In: Auer DE, Houghton E, eds. Proceedings of the 13th International Conference of Racing Analysts and Veterinarians. R&W Publications; 2000:29-33.
  162. McKinney AR. Modern techniques for the determination of anabolic-androgenic steroid doping in the horse.. Bioanalysis 2009;1(4):785-803.
    doi: 10.4155/bio.09.52google scholar: lookup
  163. Le Bizec B, Courant F, Gaudin I. Criteria to distinguish between natural situations and illegal use of boldenone, boldenone esters and boldione in cattle.1. Metabolite profiles of boldenone, boldenonen esters and boldione in cattle urine.. Steroids 2006;71(13-14):1078-1087.
    doi: 10.1016/j.steroids.2006.09.009google scholar: lookup
  164. You Y, Uboh CE, Soma LR. Simultaneous determination of testosterone and testosterone enanthate in equine plasma by UHPLC-MS-MS.. Chromatographia 2010;72(11-12):1097-1106.
    doi: 10.1365/s10337-010-1784-6google scholar: lookup
  165. Gray BP, Viljanto M, Bright J, Pearce C, Maynard S. Investigations into the feasibility of routine ultra high performance liquid chromatography-tandem mass spectrometry analysis of equine hair samples for detecting the misuse of anabolic steroids, anabolic steroid esters and related compounds.. Anal Chim Acta 2013;787:163-172.
    doi: 10.1016/j.aca.2013.05.058google scholar: lookup
  166. Anielski P. Hair analysis of anabolic steroids in connection with doping control-results from horse samples.. J Mass Spectrom 2008;43(7):1001-1008.
    doi: 10.1002/jms.1446google scholar: lookup
  167. Kwok KY, Choi TLS, Kwok WH, Wong JKY, Wan TSM. Detection of anabolic and androgenic steroids and/or their esters in horse hair using ultra-high performance liquid chromatography-high resolution mass spectrometry.. J Chromatogr a 2017;1493:76-86.
    doi: 10.1016/j.chroma.2017.03.007google scholar: lookup
  168. Choi TLS, Kwok KY, Kwok WH, Tsoi YYK, Wong JKY, Wan TSM. Detection of seventy-two anabolic and androgenic steroids and/or their esters in horse hair using ultra-high performance liquid chromatography-high resolution mass spectrometry in multiplexed targeted MS2 mode and gas chromatography-tandem mass spectrometry.. J Chromatogr a 2018;1566:51-63.
    doi: 10.1016/j.chroma.2018.06.049google scholar: lookup
  169. Moeller BC, Yang Z. Evaluation of dried blood spots as an alternative sample matrix for equine antidoping analysis.. Drug Test Anal 2021;13(2):386-396.
    doi: 10.1002/dta.2934google scholar: lookup
  170. Solheim SA, Stillesby Levernaes MC, Mørkeberg J. Stability and detectability of testosterone esters in dried blood spots after intramuscular injections.. Drug Test Anal 2022;14(11-12):1926-1937.
    doi: 10.1002/dta.3030google scholar: lookup
  171. Jing J, Shan Y, Liu Z. Automated online dried blood spot sample preparation and detection of anabolic steroid esters for sports doping testing.. Drug Test Anal 2022;14(6):1040-1052.
    doi: 10.1002/dta.3226google scholar: lookup
  172. Houghton E, Ginn A, Teale P, Dumasia MC, Moss MS. Detection of the administration of anabolic preparation of nandrolone to the entire male horse.. Equine Vet J 1986;18(6):491-493.
    doi: 10.1111/j.2042-3306.1986.tb03701.xgoogle scholar: lookup
  173. Houghton E, Ginn A, Teale P, Dumasia MC. Testosterone administration to the colt: approached to the problem.. In: Tobin T, Blake J, Potter M, Wood T, eds. Proceedings of the 7th International Conference of Racing Analysts and Veterinarians. University of Kentucky; 1988:495-498.
  174. Cawley AT, Kazlauskas R, Trout GJ, Rogerson JH, George AV. Isotopic fractionation of endogenous anabolic-androgenic steroids and its relationship to doping control in sports.. J Chromatogr Sci 2005;43(1):32-38.
    doi: 10.1093/chromsci/43.1.32google scholar: lookup
  175. World Anti-Doping Agency. 2022 WADA technical document-TD2022IRMS. Accessed on 12 June 2023. https://www.wada-ama.org/sites/default/files/2022-01/td2022irms_v1.0_final_eng_0_0.pdf
  176. Balizs G, Jainz A, Horvatovich P. Investigation of the feeding effect on the 13C/12C isotope ratio of the hormones in bovine urine using gas chromatography/combustion isotope ratio mass spectrometry.. J Chromatogr a 2005;1067(1-2):323-330.
    doi: 10.1016/j.chroma.2004.09.097google scholar: lookup
  177. Yamada M, Kinoshita K, Kurosawa M, Saito K, Nakazawa H. Analysis of exogenous nandrolone metabolite in horse urine by gas chromatography/combustion/carbon isotope ratio mass spectrometry.. J Pharm Biomed Anal 2007;45(4):654-658.
    doi: 10.1016/j.jpba.2007.07.005google scholar: lookup
  178. Cawley A, Keen B, Tou K, Elbourne M, Keledjian J. Biomarker ratios.. Drug Test Anal 2022;14(5):983-990.
    doi: 10.1002/dta.3250google scholar: lookup
  179. Duluard A, Bailly-Chouriberry L, Kieken F, Popot M-A, Bonnaire Y. Longitudinal follow-up on racehorses: Veterinary and analytical issues. A one-year study of French trotters.. In: Beresford GD, Howitt RG, eds. Proceedings of the 18th International Conference of Racing Analysts and Veterinarians. New Zealand; 2012:27-34.
  180. Sottas PE, Baume N, Saudan C, Schweizer C, Kamber M, Saugy M. Bayesian detection of abnormal values in longitudinal biomarkers with an application to the T:E ratio.. Biostatistics 2007;8(2):285-296.
    doi: 10.1093/biostatistics/kxl009google scholar: lookup
  181. Saugy N, Lundby C, Robinson N. Monitoring of biological markers indicative of doping: the athlete biological passport.. Br J Sport Med 2014;48(10):827-832.
    doi: 10.1136/bjsports-2014-093512google scholar: lookup
  182. Mareck U, Geyer H, Opfermann G, Thevis M, Schänzer W. Factors influencing the steroid profile in doping control analysis.. J Mass Spectrom 2008;43(7):877-891.
    doi: 10.1002/jms.1457google scholar: lookup
  183. Kuuranne T, Saugy M, Baume N. Confounding factors and genetic polymorphism in the evaluation of individual steroid profiling.. Br J Sports Med 2014;48(10):848-855.
    doi: 10.1136/bjsports-2014-093510google scholar: lookup
  184. Cloteau C, Dervilly G, Loup B. Performance assessment of an equine metabolomics model for screening a range of anabolic agents.. Metabolomics 2023;19(4):38.
    doi: 10.1007/s11306-023-01985-0google scholar: lookup
  185. Keen B, Cawley A, Reedy B, Fu S. Metabolomics in clinical and forensic toxicology, sports anti-doping and veterinary residues.. Drug Test Anal 2022;14(5):794-807.
    doi: 10.1002/dta.3245google scholar: lookup
  186. Kaabia Z, Dervilly-Pinel G, Popot MA. Monitoring the endogenous steroid profile disruption in urine and blood upon nandrolone administration: an efficient and innovative strategy to screen for nandrolone abuse in entire male horses.. Drug Test Anal 2014;6(4):376-388.
    doi: 10.1002/dta.1520google scholar: lookup
  187. Chan GHM, Ho ENM, Leung DKK, Wong KS, Wan TSM. Targeted metabolomics approach to detect the misuse of steroidal aromatase inhibitors in equine sports by biomarker profiling.. Anal Chem 2016;88(1):764-772.
    doi: 10.1021/acs.analchem.5b03165google scholar: lookup
  188. Cloteau C, Dervilly G, Kaabia Z. From a non-targeted metabolomics approach to a targeted biomarkers strategy to highlight testosterone abuse in equine. Illustration of a methodological transfer between platforms and laboratories.. Drug Test Anal 2022;14(5):864-878.
    doi: 10.1002/dta.3221google scholar: lookup
  189. Stojiljkovic N, Bubanj S, Djordjevic M. Urine fingerprints of stanozolol treated horses by liquid chromatography high resolution mass spectrometry.. J Sports Med Doping Stud 2017;7:2161-2673.
  190. Stojiljkovic N, Leroux F, Bubanj S. Tracking main environmental factors masking a minor steroidal doping effect using metabolomic analysis of horse urine by liquid chromatography-high-resolution mass spectrometry.. Eur J Mass Spectrometry 2019;25(3):339-353.
    doi: 10.1177/1469066719839034google scholar: lookup
  191. Barton C, Beck P, Kay R, Teale P, Roberts J. Multiplexed LC-MS/MS analysis of horse plasma proteins to study doping in sport.. Proteomics 2009;9(11):3058-3065.
    doi: 10.1002/pmic.200800737google scholar: lookup
  192. Labrie F, Luu-The V, Calvo E. Tetrahydrogestrinonone induces a genomic signature typical of a potent anabolic steroid.. J Endocrinol 2005;184(2):427-433.
    doi: 10.1677/joe.1.05997google scholar: lookup
  193. Dervilly-Pinel G, Royer A-L, Bozzetta E. When LC-HRMS metabolomics gets ISO17025 accredited and ready for official controls-application to the screening of forbidden compounds in livestock.. Food Additives Contaminants: Part a 2018;35(10):1948-1958.
    doi: 10.1080/19440049.2018.1496280google scholar: lookup

Citations

This article has been cited 0 times.
Subscribe to our newsletter
Join 99,357 horse owners like you who receive our email updates on horse health and nutrition.