Animal Reproduction (AR)
Animal Reproduction (AR)

Additional effects using progestins in mares on levels of thyroid hormones and steroids in neonates

Ana Carolina Rusca Correa Porto; Mariana Abreu Redoan; Cristina Oliveira Massoco; Priscila Viau Furtado; Claudio Alvarenga Oliveira

Downloads: 2
Views: 207


Abstract: The risk of pregnancy loss in mares leads to the use of exogenous hormones to help pregnancy maintenance. The objective was to evaluate the proportion of thyroid hormones and steroids in neonates, in the following postpartum period, born to mares fed with synthetic progesterone and to verify the existence of a correlation between the level of progesterone between mother and neonate. Twenty-seven mares and their foals were used. The animals were divided into 5 experimental groups: group 1 (control, without hormonal supplementation), group 2 (random samples fed to 120 days of pregnancy with long-term progesterone), group 3 (mares fed with short-term progesterone as of 280.º day of pregnancy), group 4 (mares fed with long-term progesterone as of 280.º day of pregnancy) and group 5 (mares fed with synthetic hormone [altrenogest] as of 280.º day of pregnancy). The animal’s blood collection took place immediately after parturition for the hormonal measurement. The hormones measured in neonates were total T3, free T4, TSH, progesterone and cortisone. In mares, only levels of progesterone. The groups of neonates showed no difference on levels of total T3, free T4, TSH and progesterone. There was no difference on levels of progesterone in mares among the groups. Neonates from groups 4 and 5 had higher and lower cortisone levels, respectively. No neonate showed clinical change. There was also no correlation between levels of progesterone in mares and foals. Thus, hormonal supplementation with long-term progesterone as of 280 days of pregnancy leds to an increase in the neonate's cortisone levels, in the meantime, supplementation with altrenogest as of 280 days of pregnancy caused a decrease on cortisone levels in foals, despite clinical signs have not been observed on these animals.


altrenogest, progesterone, cortisone, equine, pregnancy


Allen WR. Luteal deficiency and embryo mortality in the mare. Reprod Domest Anim. 2001;36(3-4):121-31.

Bamberger AM, Jenatschke S, Schulte HM, Löning T, Bamberger MC. Leukemia inhibitory factor (LIF) stimulates the human HLA-G promoter in JEG3 choriocarcinoma cells. J Clin Endocrinol Metab. 2000;85(10):3932-6.

Barker PM, Walters DV, Markiewicz M, Strang LB. Development of the lung liquid reabsorptive mechanism in fetal sheep: synergism of triiodothyronine and hydrocortisone. J Physiol. 1991;433(1):435-49.

Berg EL, McNamara DL, Keisler DH. Endocrine profiles of periparturient mares and their foals. J Anim Sci. 2007;85(7):1660-8.

Breuhaus BA. Thyroid function and dysfunction in term and premature equine neonates. J Vet Intern Med. 2014;28(4):1301-9.

Cain DW, Cidlowski JA. Immune regulation by glucocorticoids. Nat Rev Immunol. 2017;17(4):233-47.

Chavatte P, Holtan D, Ousey JC, Rossdale PD. Biosynthesis and possible biological roles of progestagens during equine pregnancy and in the newborn foal. Equine Vet J. 1997;29(24):89-95.

DeLuca CA, McCue PM, Patten ML, Squires EL. Effect of a nonsurgical embryo transfer procedure and/or altrenogest therapy on endogenous progesterone concentration in mares. J Equine Vet Sci. 2011;31(2):57-62.

Fedorka CE, Ball BA, Walker OF, Conley AJ, Corbin CJ, Lu KG, Hanneman JM, Troedsson MHT, Adams AA. Alteration of the mare’s immune system by the synthetic progestin, altrenogest. Am J Reprod Immunol. 2019;82(2):e13145.

Forhead AJ, Fowden AL. Thyroid hormones in fetal growth and prepartum maturation. J Endocrinol. 2014;221(3):R87-103.

Fowden AL, Forhead AJ, Ousey JC. Endocrine adaptations in the foal over the perinatal period. Equine Vet J. 2012;44(41):130-9.

Fowden AL, Silver M. Comparative development of the pituitary-adrenal axis in the fetal foal and lamb. Reprod Domest Anim. 1995;30(4):170-7.

Frank N, Sojka J, Messer NT 4th. Equine thyroid dysfunction. Vet Clin North Am Equine Pract. 2002;18(2):305-19.

Goddard LM, Ton AN, Org T, Mikkola HKA, Iruela-Arispe ML. Selective suppression of endothelial cytokine production by progesterone receptor. Vascul Pharmacol. 2013;59(1-2):36-43.

Hart KA, Barton MH. Adrenocortical insufficiency in horses and foals. Vet Clin North Am Equine Pract. 2011;27(1):19-34.

Holtan DW, Houghton E, Silver M, Fowden AL, Ousey J, Rossdale PD. Plasma progestagens in the mare, fetus and newborn foal. J Reprod Fertil Suppl. 1991;44:517-28.

Houghton E, Holtan D, Grainger L, Voller BE, Rossdale PD, Ousey JC. Plasma progestagen concentrations in the normal and dysmature newborn foal. J Reprod Fertil Suppl. 1991;44:609-17.

Huijbregts RPH, Helton ES, Michel KG, Sabbaj S, Richter HE, Goepfert PA, Hel Z. Hormonal contraception and HIV-1 Infection: medroxyprogesterone acetate suppresses innate and adaptive immune mechanisms. Endocrinology. 2013;154(3):1282-95.

Jackson SA, Squires EL, Nett TM. The effect of exogenous progestins on endogenous progesterone secretion in pregnant mares. Theriogenology. 1986;25(2):275-9.

Jeffcott LB, Rossdale PD, Leadon DP. Haematological changes in the neonatal period of normal and induced premature foals. J Reprod Fertil Suppl. 1982;32:537-44.

Knottenbelt D, Holdstock N, Madigan J. Equine neonatal medicine and surgery. Philadelphia: Saunders; 2004. Perinatal review; p. 15-43.

Koubovec D, Berghe WV, Vermeulen L, Haegeman G, Hapgood JP. Medroxyprogesterone acetate downregulates cytokine gene expression in mouse fibroblast cells. Mol Cell Endocrinol. 2004;221(1-2):75-85.

LeBlanc MM, MacPherson M, Sheerin P. Ascending placentitis: what we know about pathophysiology, diagnosis, and treatment. In: AAEP Annual Convention [Internet]; 2004; Denver. Lexington, KY: American Association of Equine Practitioners; 2004 [cited 2021 Jul 27]. Available from:

Lester GD. Maturity of the neonatal foal. Vet Clin North Am Equine Pract. 2005;21(2):333-55.

Machnik M, Hegger I, Kietzmann M, Thevis M, Guddat S, Schänzer W. Pharmacokinetics of altrenogest in horses. J Vet Pharmacol Ther. 2007;30(1):86-90.

Madigan JE, Haggettt EF, Pickles KJ, Conley A, Stanley S, Moeller B, Toth B, Aleman M. Allopregnanolone infusion induced neurobehavioural alterations in a neonatal foal: is this a clue to the pathogenesis of neonatal maladjustment syndrome? Equine Vet J. 2012;109-12(41):109-12.

McConaghy FF, Green LA, Colgan S, Morris LH. Studies of the pharmacokinetic profile, in vivo efficacy and safety of injectable altrenogest for the suppression of oestrus in mares. Aust Vet J. 2016;94(7):248-55.

Messer NT 4th, Thomas Riddle W, Traub-Dargatz JL, Dargatz DA, Refsal KJ, Thompson DL. Thyroid hormone levels in thoroughbred mares and their foals at parturition. AAEP Proc. 1998;44:248-51.

Minitab. Minitab®19 [Internet]. 2019 [cited 2021 Jul 27]. Available from:

Müller V, Curcio BR, Toribio RE, Feijó LS, Borba LA, Canisso IF, Nogueira CEW. Cortisol, progesterone, 17α-OH-progesterone, and pregnenolone in foals born from mare’s hormone-treated for experimentally induced ascending placentitis. Theriogenology. 2019;123:139-44.

Neuhauser S, Palm F, Ambuehl F, Aurich C. Effects of altrenogest treatment of mares in late pregnancy on parturition and on neonatal viability of their foals. Exp Clin Endocrinol Diabetes. 2008;116(7):423-8.

Neuhauser S, Palm F, Ambuehl F, Möstl E, Schwendenwein I, Aurich C. Effects of altrenogest treatment of mares in late pregnancy on parturition and on neonatal viability of their foals. Equine Vet J. 2009;41(6):572-7.

Ousey J, Rossdale P, Palmer L, Houghton E, Grainger L, Fowden A. Effects of progesterone administration to mares during late gestation. Theriogenology. 2002;58(2-4):793-5.

Palm FM, Schenk I, Neuhauser S, Schubert D, Machnik M, Schänzer W, Aurich C. Concentrations of altrenogest in plasma of mares and foals and in allantoic and amniotic fluid at parturition. Theriogenology. 2010;74(2):229-35.

Panzani S, Villani M, McGladdery A, Magri M, Kindahl H, Galeati G, Martino PA, Veronesi MC. Concentrations of 15-ketodihydro-PGF2alpha, cortisol, and progesterone in the plasma of healthy and pathologic newborn foals. Theriogenology. 2009;72(8):1032-40.

Ramminger SJ, Inglis SK, Olver RE, Wilson SM. Hormonal modulation of Na(+) transport in rat fetal distal lung epithelial cells. J Physiol. 2002;544(2):567-77.

Riccardi C, Bruscoli S, Migliorati G. Molecular mechanisms of immunomodulatory activity of glucocorticoids. Pharmacol Res. 2002;45(5):361-8.

Rose BV, Firth M, Morris B, Roach JM, Wathes DC, Verheyen KLP, de Mestre AM. Descriptive study of current therapeutic practices, clinical reproductive findings and incidence of pregnancy loss in intensively managed thoroughbred mares. Anim Reprod Sci. 2018;188:74-84.

Rossdale PD, Ousey JC, McGladdery AJ, Prandi S, Holdstock N, Grainger L, Houghton E. A retrospective study of increased plasma progestagen concentrations in compromised neonatal foals. Reprod Fertil Dev. 1995;7(3):567-75.

Shoemaker CF, Squires EL, Shideler RK. Safety of altrenogest in pregnant mares and on health and development of offspring. J Equine Vet Sci. 1989;9(2):69-72.

Silver M, Ousey JC, Dudan FE, Fowden AL, Knox J, Cash RS, Rossdale PD. Studies on equine prematurity 2: post natal adrenocortical activity in relation to plasma adrenocorticotrophic hormone and catecholamine levels in term and premature foals. Equine Vet J. 1984;16(4):278-86.

Silver M. Prenatal maturation, the timing of birth and how it may be regulated in domestic animals. Exp Physiol. 1990;75(3):285-307.

Willmann C, Budik S, Walter I, Aurich C. Influences of treatment of early pregnant mares with the progestin altrenogest on embryonic development and gene expression in the endometrium and conceptus. Theriogenology. 2011;76(1):61-73.

Wynn MAA, Esteller-Vico A, Legacki EL, Conley AJ, Loux SC, Stanley SD, Curry TE Jr, Squires EL, Troedsson MH, Ball BA. A comparison of progesterone assays for determination of peripheral pregnane concentrations in the late pregnant mare. Theriogenology. 2018;106:127-33.

Submitted date:

Accepted date:

6579bad5a953955ce40aab33 animreprod Articles
Links & Downloads

Anim Reprod

Share this page
Page Sections