A review of current chemistry, pharmacology, and regulation of endogenous anabolic steroids testosterone, boldenone, and nandrolone in horses.
Abstract: Anabolic androgenic steroids are synthetic substances related to the male sex hormones (androgens). These agents promote the growth of skeletal muscle (anabolic effects) and the development of male sexual characteristics (androgenic effects). Anabolic steroids have been illegally used for many years as performance-enhancing drugs in human, equine, and canine sports and as growth promoters in livestock reared to provide meat for human consumption. The analytical challenge to developing effective means of control within these fields has been exacerbated by the reported endogenous nature of some of these steroids. Anabolic steroids have been employed extensively in equine practice over the past 50 years. Their usefulness is largely dependent on subjective opinions, as only minimal studies investigating pharmacodynamics have been carried out in horses. Therefore, their use will vary markedly between practitioners depending on their personal experiences and pressures by trainers to use them. They form part of rational therapy in a variety of conditions. In addition to their use for increasing muscle mass, they are used to varying extents in the raising of yearlings and in the training and racing of horses with the view of improving performance. The use of these agents is prohibited in the horseracing industry by the Association of Racing Commissioners International (ARCI), International Federation of Horseracing Authorities (IFHA), and Fédération Equestre Internationale (FEI).
© 2023 John Wiley & Sons Ltd.
Publication Date: 2023-06-01 PubMed ID: 37264491DOI: 10.1111/jvp.13397Google 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.
- 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.
The research article explores the use, effects, and regulation of anabolic androgenic steroids, specifically testosterone, boldenone, and nandrolone, in horses. It touches on their role in enhancing performance in equestrian sports and growth in livestock, as well as the challenges in monitoring and controlling their use due to their endogenous nature.
Understanding Anabolic Androgenic Steroids
- Anabolic androgenic steroids are synthetic substances tied to male sex hormones, known as androgens. They aid in muscle growth (anabolic effect) and the development of male sexual characteristics (androgenic effect).
- These steroids have been misused for performance enhancement in human, equine, and canine sports. They are also used as growth boosters in livestock meant for human consumption.
- The control and monitoring of these substances pose analytical challenges, in part because some of these steroids are endogenous, meaning they’re produced by organisms naturally.
The Use of Anabolic Steroids in Horses
- For the past five decades, the use of anabolic steroids in horses has been extensive.
- The degree of their usefulness is largely based on subjective views, as there is a minimal amount of studies looking into the pharmacodynamics of these substances in horses.
- The use of these steroids varies greatly among practitioners depending on personal experiences and pressure from trainers.
- These agents are used as part of treatment for different conditions. Beyond muscle mass improvement, they’re used in raising yearlings and in the training and racing of horses to enhance performance.
Regulations Regarding Anabolic Steroids in Horseracing
- The use of anabolic steroids in horseracing is prohibited by various organizations like the Association of Racing Commissioners International (ARCI), International Federation of Horseracing Authorities (IFHA), and Fédération Equestre Internationale (FEI).
Cite This Article
APA
Dirikolu L, Lehner AF.
(2023).
A review of current chemistry, pharmacology, and regulation of endogenous anabolic steroids testosterone, boldenone, and nandrolone in horses.
J Vet Pharmacol Ther, 46(4), 201-217.
https://doi.org/10.1111/jvp.13397 Publication
Researcher Affiliations
- Department of Comparative Biomedical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, USA.
- MSU Veterinary Diagnostic Laboratory, Section of Toxicology, Michigan State University, East Lansing, Michigan, USA.
MeSH Terms
- Horses
- Animals
- Male
- Dogs
- Humans
- Anabolic Androgenic Steroids
- Nandrolone / pharmacology
- Doping in Sports
- Testosterone
- Androgens / pharmacology
- Steroids / chemistry
- Anabolic Agents / pharmacology
- Anabolic Agents / chemistry
References
This article includes 103 references
- Anawalt BD. Diagnosis and management of anabolic androgenic steroid use. Journal of Clinical Endocrinology & Metabolism 2019;104(7):2490-2500.
- Anielski P, Thieme D, Schlupp A, Grosse J, Ellendorff F, Mueller RK. Detection of testosterone, nandrolone and precursors in horse hair. Analytical and Bioanalytical Chemistry 2005;383(6):903-908.
- ARCI. ARCI model rules of racing - version 11. 2021.
- Ayotte C. Detecting the administration of endogenous anabolic androgenic steroids. Handbook of experimental pharmacology 2010;Vol. 195:87-107.
- Bellemare V, Faucher F, Breton R, Luu-The V. Characterization of 17α-hydroxysteroid dehydrogenase activity (17α-HSD) and its involvement in the biosynthesis of epitestosterone. BMC Biochemistry 2005;6:12.
- Bergman R, Leach RE. The use and abuse of anabolic steroids in Olympic-caliber athletes. Clinical Orthopaedics and Related Research 1985;198:169-172.
- Bond P, Smit DL, de Ronde W. Anabolic-androgenic steroids: How do they work and what are the risks?. Frontiers in Endocrinology 2022;13:1059473.
- Bonnaire, Y., Dehennin, L., Plou, P., Toutain, P. L., Ginn, A., Grainger, L., Armstrong, R., Dumasia, M. C., Nedderman, A., Houghton, E., Tang, P. W., Law, W. C., & Crone, D. L. (1996). In D. E. Auer & E. Houghton (Eds.), Proceedings of the 11th International conference of racing analysts and veterinarians (pp. 56-61). R&W Publications.
- Burger HG. Androgen production in women. Fertility and Sterility 2002;77(Suppl. 4):3-5.
- Büttner A, Thieme D. Side effects of anabolic androgenic steroids: Pathological findings and structure-activity relationships. Handbook of Experimental Pharmacology 2010;195:459-484.
- Conn PM. Animal models for the study of human disease. 2013;p. 376.
- Cordaro FG, Lombardo S, Cosentino M. Selling androgenic anabolic steroids by the pound: Identification and analysis of popular websites on the Internet. Scandinavian Journal of Medicine & Science in Sports 2011;21(6):e247-e259.
- Courtot D, Guyot JL, Benoit E. Urinary excretion of physiological 19- nortestosterone in the colt. Comptes Rendus de l'Academie des Sciences III (Sciences de la Vie) 1984;299:139-141.
- Decloedt A, Bailly-Chouriberry L, Vanden Bussche J, Garcia P, Popot MA, Bonnaire Y, Vanhaecke L. A validated UHPLC-MS/MS method to quantify low levels of anabolic-androgenic steroids naturally present in urine of untreated horses. Analytical and Bioanalytical Chemistry 2015;407(15):4385-4396.
- Decloedt AI, Bailly-Chouriberry L, Vanden Bussche J, Garcia P, Popot MA, Bonnaire Y, Vanhaecke L. In vitro simulation of the equine hindgut as a tool to study the influence of phytosterol consumption on the excretion of anabolic-androgenic steroids in horses. The Journal of Steroid Biochemistry and Molecular Biology 2015;152:180-192.
- 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 Veterinary Journal 2007;39(2):186-188.
- Dehennin, L., Bonnaire, Y., Plou, P., Ho, E. N. M., Yiu, K. C. H., & Wan, T. S. M. (2003). In D. W. Hill & T. Hill (Eds.), Proceedings of the 14th International conference of racing analysts and veterinarians (p. 58). R. & W Publications (Newmarket) Ltd.
- Dehennin L, Petit E, Bonnaire Y, Bruyas JF, Le Bizec B, Plou P. Urinary excretion of 5(10)-estrene-3beta,17alpha-diol and estrone by the female horse: Complementary indicators of early pregnancy screened with regard to a putative anabolic doping practice. The Journal of Steroid Biochemistry and Molecular Biology 2007;104(1-2):85-91.
- Dhakal P, Hirama A, Nambo Y, Harada T, Sato F, Nagaoka K, Watanabe G, Taya K. Circulating pituitary and gonadal hormones in spring-born thoroughbred fillies and colts from birth to puberty. The Journal of Reproduction and Development 2012;58(5):522-530.
- Dubey S, Beotra A. Identification of Nandrolone and its metabolite 5α-Estran-3β, 17α-diol in horse urine after chemical derivatization by liquid chromatography tandem mass spectrometry. Mass Spectrometry Letters 2017;8(4):90-97.
- 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.
- 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.
- 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. Biomedical & Environmental Mass Spectrometry 1988;17(5):383-392.
- Dumasia MC, Houghton E, Jackiw M. Steroids in equine testes: the identification of endogenous 19-hydroxy and 19-nor neutral steroids by gas chromatography-mass spectrometry. The Journal of Endocrinology 1989;120(2):223-229.
- 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. Journal of Chromatography 1986;377:23-33.
- Elks J. The dictionary of drugs: Chemical data, structures and bibliographies. 2014.
- Equimed staff. Anabolic steroids. 2014.
- FEI. Equine prohibited substances list. 2022.
- Fidani M, Gamberini MC, Pasello E, Palazzoli F, De Iuliis P, Montana M, Arioli F. Evaluation of equine urine reactivity towards phase II metabolites of 17-hydroxy steroids by liquid chromatography/tandem mass spectrometry. Rapid Communications in Mass Spectrometry 2009;23(1):65-76.
- Fleming BO. Characterization and evaluation of androgen-binding protein, sex hormone-binding globulin, and thyroxine-binding globulin in the horse. Theses and dissertations - Veterinary science. University of Kentucky, Lexington KY 2018.
- Gerald T, Raj G. Testosterone and the androgen receptor. Urologic Clinics of North America 2022;49:603-614.
- Gómez C, Pozo OJ, Geyer H, Marcos J, Thevis M, Schänzer W, Segura J, Ventura R. New potential markers for the detection of boldenone misuse. The Journal of Steroid Biochemistry and Molecular Biology 2012;132(3-5):239-246.
- Gower DB, Houghton E, Kicman AT. Anabolic steroids: Metabolism, doping and detection in equestrian and human sports. Steroid analysis 1995.
- 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 Communications in Mass Spectrometry 2008;22:2999-3007.
- 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 Testing and Analysis 2011;3(4):206-213.
- 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. Analytica Chimica Acta 2013;787:163-172.
- 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. The Journal of Steroid Biochemistry and Molecular Biology 2012;128(1-2):1-11.
- H.R.1754. Horseracing integrity and safety act of 2020. 2020.
- Hartgens F, Kuipers H. Effects of androgenic-anabolic steroids in athletes. Sports Medicine 2004;34(8):513-554.
- HISA Protocol. HISA equine anti-doping and medication control protocol. 2023.
- Ho EN, Kwok WH, Leung DK, Riggs CM, Sidlow G, Stewart BD, Wong AS, Wan TS. Control of the misuse of testosterone in castrated horses based on an international threshold in plasma. Drug Testing and Analysis 2015;7(5):414-419.
- Ho EN, Yiu KC, Tang FP, Dehennin L, Plou P, Bonnaire Y, Wan TS. Detection of endogenous boldenone in the entire male horses. Journal of Chromatography. B, Analytical Technologies in the Biomedical and Life Sciences 2004;808(2):287-294.
- Hoffmann B, Landeck A. Testicular endocrine function, seasonality, and semen quality of the stallion. Animal Reproduction Science 1999;57(1-2):89-98.
- Houghton E. Studies related to the metabolism of anabolic steroids in the horse: 19-Nortestosterone. Xenobiotica 1977;7(11):683-693.
- Houghton E. Anabolic steroids in the horse - A review of current knowledge. 1992.
- Houghton E, Copsey J, Dumasia MC, Haywood PE, Moss MS, Teale P. The identification of C-18 neutral steroids in normal stallion urine. Biomedical Mass Spectrometry 1984;11(2):96-99.
- 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.
- Houghton E, Ginn A. Nandrolone in the colt: A review of the science relating to the threshold value. Proceedings of the 7th International conference of racing analysts and veterinarians, Louisville, Kentucky, USA 1988;p. 29.
- Houghton E, Ginn A, Teale P, Dumasia MC, Copsey J. Comparison of the use of mass spectrometry and methylene unit values in the determination of the stereochemistry of estranediol, the major urinary metabolite of 19-nortestosterone in the horse. Journal of Chromatography 1989;479(1):73-83.
- Houghton E, Ginn A, Teale P, Dumasia MC, Moss MS. Detection of the administration of anabolic preparations of nandrolone to the entire male horse. Equine Veterinary Journal 1986;18(6):491-493.
- Houghton E, Maynard S. Some aspects of doping and medication control in equine sports. Handbook of Experimental Pharmacology 2010;195:369-409.
- Houghton E, Oxley GA, Moss MS, Evans S. Studies related to the metabolism of anabolic steroids in the horse: A gas chromatographic mass spectrometric method to confirm the administration of 19-nortestosterone or its esters to horses. Biomedical Mass Spectrometry 1978;5(2):170-173.
- Houghton E, Teale P, Dumasia MC. 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. Analytica Chimica Acta 2007;586:196-207.
- IFHA. Article 6. 2023.
- Index Nominum. International drug directory (2000). 2000.
- International Federation of Horseracing Authorities (IFHA). Article 6E, International Agreement on Breeding, Racing and Wagering (IABRW). 2022.
- Kaabia Z, Dervilly-Pinel G, Hanganu F, Cesbron N, Bichon E, Popot MA, Bonnaire Y, Le Bizec B. 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. Journal of Chromatography. A 2013;1284:126-140.
- Kaabia Z, Dervilly-Pinel G, Popot MA, Bailly-Chouriberry L, Plou P, Bonnaire Y, Le Bizec B. 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 Testing and Analysis 2014;6(4):376-388.
- Kam PCA, Yarrow M. Anabolic steroid abuse: Physiological and anaesthetic considerations. Anaesthesia 2005;60(7):685-692.
- Kicman AT. Pharmacology of anabolic steroids. British Journal of Pharmacology 2008;154(3):502-521.
- Kintz P, Cirimele V, Dumestre-Toulet V, Ludes B. Doping control for nandrolone using hair analysis. Journal of Pharmaceutical and Biomedical Analysis 2001;24(5-6):1125-1130.
- Kintz P, Cirimele V, Sachs H, Jeanneau T, Ludes B. Testing for anabolic steroids in hair from two bodybuilders. Forensic Science International 1999;101(3):209-216.
- Knight, P. K., & Suann, C. J. (2010). Poster presented at the 18th International conference of racing analysts and veterinarians, Queenstown, New Zealand.
- Kuhn CM. Anabolic steroids. Recent Progress in Hormone Research 2002;57:411-434.
- 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. Journal of Chromatography. A 2017;1493:76-86.
- Lister, T. (2002). In C. Osborne & M. Pack (Eds.), Chemistry at the races: The work of the horseracing forensic laboratory. Royal Society of Chemistry.
- Llewellyn W. Anabolics. 2011.
- Marshall DE, Gower DB, Houghton E, Dumasia MC. Studies of testosterone metabolism in equine placental tissue. Biochemical Society Transactions 1990;17(6):1018-1019.
- McKinney AR. Modern techniques for the determination of anabolic-androgenic steroid doping in the horse. Bioanalysis 2009;1(4):785-803.
- Merck Vet Manual. Pharmacology. The Merck veterinary manual 2005;9th ed..
- Mueller JW, Gilligan LC, Idkowiak J, Arlt W, Foster PA. The regulation of steroid action by sulfation and desulfation. Endocrine Reviews 2015;36(5):526-563.
- Nieschlag E, Nieschlag S. The history of discovery, synthesis, and development of testosterone for clinical use. European Journal of Endocrinology 2019;180:R201-R212.
- Plotka ED, Vevea DN, Eagle TC, Siniff DB, Tester JR. Ovarian function in captive feral mares. Journal of Wildlife Diseases 1989;25(4):574-579.
- 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 androsta-1,4-diene-3,17-dione (boldione). Biomedical Chromatography 2008;22(6):662-670.
- Pozo OJ, Van Eenoo P, Deventer K, Delbeke FT. Detection and characterization of anabolic steroids in doping analysis by LC-MS. Trends in Analytical Chemistry 2008;27:657-671.
- Rodd C, Jourdain N, Alini M. Action of estradiol on epiphyseal growth plate chondrocytes. Calcified Tissue International 2004;75(3):214-224.
- Roig M, Segura J, Ventura R. Quantitation of 17beta-nandrolone metabolites in boar and horse urine by gas chromatography-mass spectrometry. Analytica Chimica Acta 2007;586(1-2):184-195.
- Sato T, Miyagawa S, Iguchi T. Estrone. Handbook of hormones 2016.
- Scarth J, Akre C, van Ginkel L, Le Bizec B, De Brabander H, Korth W, Points J, Teale P, Kay J. Presence and metabolism of endogenous androgenic-anabolic steroid hormones in meat-producing animals: A review. Food Additives & Contaminants. Part A, Chemistry, Analysis, Control, Exposure & Risk Assessment 2009;26(5):640-671.
- Scarth JP, Teale P, Kuuranne T. Drug metabolism in the horse: A review. Drug Test Analysis 2011;3:19-53.
- Schänzer W, Geyer H, Gotzmann A, Horning S, Mareck-Engelke U, Nitschke R, Nolteernsting E, Donike M. Endogenous production, and excretion of boldenone (17beta-hydroxyandrosta-1,4-dien-3-one), an androgenic anabolic steroid. Proceedings of the Manfred Donike workshop 12th Cologne workshop on dope analysis. Recent advances in doping analysis 2 1994;p. 211.
- Simpson ER, Clyne C, Rubin G, Boon WC, Robertson K, Britt K, Speed C, Jones M. Aromatase - a brief overview. Annual Review of Physiology 2002;64:93-127.
- Snow DH. Anabolic steroids. The Veterinary Clinics of North America. Equine Practice 1993;9(3):563-576.
- 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. Journal of Veterinary Pharmacology and Therapeutics 2008;31(6):587-590.
- Soma LR, Uboh CE, You Y, Guan F, McDonnell S. Plasma concentrations of testosterone and nandrolone in racing and nonracing intact male horses. Journal of Veterinary Pharmacology and Therapeutics 2012;35(2):132-138.
- Sterk S, Herbold H, Blokland M, van Rossum H, van Ginkel L, Stephany R. Nortestosterone: Endogenous in urine of goats, sheep and mares?. The Analyst 1998;123(12):2633-2636.
- Swerdloff RS, Dudley RE, Page ST, Wang C, Salameh WA. Dihydrotestosterone: Biochemistry, physiology, and clinical implications of elevated blood levels. Endocrine Reviews 2017;38(3):220-254.
- Tang, P. W., Ip, W. C., Law, W. C., Wan, T. S. M., & Crone, D. L. (1998). In B. Laviolette & M. R. Koupai-Abyazani (Eds.), Proceedings of the 12th International conference of racing analysts and veterinarians (pp. 107-112). R&W Publications.
- Tang, P. W., Law, W. C., & Crone, D. L. (1996). In D. E. Auer & E. Houghton (Eds.), Proceedings of the 11th International conference of racing analysts and veterinarians (pp. 68-72). R&W Publications.
- Teale P, Houghton E. The development of a gas chromatographic/mass spectrometric screening procedure to detect the administration of anabolic steroids to the horse. Biological Mass Spectrometry 1991;20(3):109-114.
- Teale P, Houghton E. Metabolism of anabolic steroids and their relevance to drug detection in horseracing. Bioanalysis 2010;2(6):1085-1107.
- Turcu A, Smith JM, Auchus R, Rainey WE. Adrenal androgens and androgen precursors: Definition, synthesis, regulation, and physiologic actions. Comprehensive Physiology 2014;4(4):1369-1381.
- Van der Kolk, J. H. (2014). In K. W. Hinchcliff, A. J. Kaneps, & R. J. Geor (Eds.), Equine sports medicine and surgery (2nd ed., pp. 769-785). Saunders.
- Verheyden K, Noppe H, Mortier V, Vercruysse J, Claerebout E, Van Immerseel F, Janssen CR, De Brabander HF. Formation of boldenone and boldenone-analogues by maggots of Lucilia sericata. Analytica Chimica Acta 2007;586(1-2):163-170.
- Viljanto M, Kicman AT, Walker CJ, Wolff K, Muir T, Hincks P, Biddle S, Scarth J. Bioformation of boldenone and related precursors/metabolites in equine feces and urine, with relevance to doping control. Drug Testing and Analysis 2020;12:215-229.
- Viljanto M, Scarth J, Hincks P, Hillyer L, Cawley A, Suann C, Noble G, Walker CJ, Kicman AT, Parkin MC. Application of testosterone to epitestosterone ratio to horse urine-a complementary approach to detect the administrations of testosterone and its pro-drugs in thoroughbred geldings. Drug Testing and Analysis 2017;9(9):1328-1336.
- Viljanto MJ, Kicman AT, Walker CJ, Parkin MC, Wolff K, Pearce CM, Scarth J. Elucidation of the biosynthetic pathways of boldenone in the equine testis. Steroids 2019;146:79-91.
- Villani M, Cairoli F, Kindahl H, Galeati G, Faustini M, Carluccio A, Veronesi MC. Effects of mating on plasma concentrations of testosterone, cortisol, oestrone sulphate and 15-ketodihydro-PGF2alpha in stallions. Reproduction in Domestic Animals 2006;41(6):544-548.
- Waller CC, McLeod MD. A review of designer anabolic steroids in equine sports. Drug Testing & Analysis 2017;9(9):1304-1319.
- White PC. Genetic diseases of steroid metabolism. Vitamins and Hormones 1994;49:131-195.
- Wong JKY, Leung DKK, Curl P, Schiff PJ, Lam KKH, Wan TSM. Evidence of boldenone, nandrolone, 5(10)-estrene-3β-17α-diol and 4-estrene-3,17-dione as minor metabolites of testosterone in equine. Drug Testing and Analysis 2017;9(9):1337-1348.
- Yokota-Nakagi N, Omoto S, Tazumi S, Kawakami M, Takamata A, Morimoto K. Estradiol replacement improves high-fat diet-induced insulin resistance in ovariectomized rats. Physiological Reports 2022;10(5):e15193.
- Yoshimoto FK, Guengerich FP. Mechanism of the third oxidative step in the conversion of androgens to estrogens by cytochrome P450 19A1 steroid aromatase. Journal of the American Chemical Society 2014;136(42):15016-15025.
Citations
This article has been cited 0 times.Use Nutrition Calculator
Check if your horse's diet meets their nutrition requirements with our easy-to-use tool Check your horse's diet with our easy-to-use tool
Talk to a Nutritionist
Discuss your horse's feeding plan with our experts over a free phone consultation Discuss your horse's diet over a phone consultation
Submit Diet Evaluation
Get a customized feeding plan for your horse formulated by our equine nutritionists Get a custom feeding plan formulated by our nutritionists