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Home / Equine Research Bank / Reprod Domest Anim / Pregnancy monitoring in mares: Ultrasonographic and endocrin...
Reproduction in domestic animals = Zuchthygiene2023; doi: 10.1111/rda.14392

Pregnancy monitoring in mares: Ultrasonographic and endocrine approaches.

Abstract: Methods to diagnose and monitor equine pregnancy continue to advance with improved instrumentation enabling the development of novel, non-invasive approaches to assess fetal well-being and viability using ultrasound and endocrine testing. From early embryonic loss to placentitis, that is typically encountered later in gestation, fetal viability and development as well as placental function can be evaluated using two fundamentally different, structural and functional, approaches. Ultrasound provides structural information on embryonic and fetal growth using such parameters as combined thickness of the uterus and placenta (CTUP), visual assessment of fetal fluids, activity, heart rate and multiple biometrics involving the fetal head and eyes, limbs and joints among many others, depending on the stage of gestation. Endocrine profiles that include progesterone and 5α-dihydroprogesterone, other metabolites, androgens and estrogens can be evaluated simultaneously using liquid chromatography-tandem mass spectrometry (LC-MS/MS) providing more functional information on fetal and placental competence and development. Endocrine information can be used in making clinical decisions including the need for progestin supplementation or when it can cease, and even estimating gestational stage in mares that cannot be easily palpated or scanned, as with mini-breeds or rancorous animals most notably. When used together, monitoring gestation by ultrasound and hormonal analysis provides unusual insight into feto-placental well-being and the progress of pregnancy, helping to identify problems needing therapeutic intervention.
© 2023 The Authors. Reproduction in Domestic Animals published by Wiley-VCH GmbH.
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Publication Date: 2023-05-16 PubMed ID: 37191550DOI: 10.1111/rda.14392Google Scholar: Lookup
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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 paper discusses advancements in monitoring equine pregnancy via ultrasound and endocrine testing. It describes how these techniques help evaluate fetal viability, growth, and placental function, detecting any potential issues for therapeutic intervention.

Equine Pregnancy Monitoring Methods

  • The paper identifies two primary approaches used for equine pregnancy monitoring – ultrasound and endocrine testing, offering structural and functional information respectively about the pregnancy. Ultrasound offers substantial visual data while endocrine testing provides insight into the hormonal environment of the mare during gestation.
  • The ultrasound method relies on various parameters such as the combined thickness of the uterus and placenta, visual assessment of fetal fluids, activity, and heart rate, along with several biometrics, like the fetal head and eyes measurements and limb and joint dimensions. These measures help ascertain the development stage of the fetus.
  • On the other hand, endocrine testing involves evaluating hormonal profiles, including progesterone and 5α-dihydroprogesterone, other metabolites, androgens, and estrogens, which are indicative of fetal and placental competence and development. Advanced technology like liquid chromatography-tandem mass spectrometry (LC-MS/MS) is employed for this testing.

Potential Clinical Applications

  • The data gathered from these monitoring techniques can help equine practitioners make critical clinical decisions such as the necessity and duration of progestin supplementation. It is particularly useful in determining the gestational stage in mares that can’t be easily palpated or scanned, like mini-breeds or irritable animals.
  • By combining these two methodologies, veterinarians can gain an in-depth understanding of the progression of the pregnancy and the well-being of the fetus and placenta. It aids in identifying potential issues that may require therapeutic intervention, thus contributing to better equine pregnancy management and outcomes.

Cite This Article

APA
Renaudin CD, Conley AJ. (2023). Pregnancy monitoring in mares: Ultrasonographic and endocrine approaches. Reprod Domest Anim. https://doi.org/10.1111/rda.14392

Publication

Reproduction in domestic animals = Zuchthygiene
ISSN: 1439-0531
NlmUniqueID: 9015668
Country: Germany
Language: English

Researcher Affiliations

Renaudin, Catherine D
  • Department of Population Health & Reproduction, School of Veterinary Medicine, University of California Davis, Davis, California, USA.
Conley, Alan J
  • Department of Population Health & Reproduction, School of Veterinary Medicine, University of California Davis, Davis, California, USA.

Grant Funding

  • John P. Hughes Endowment

References

This article includes 153 references
  1. Adams-Brendemuehl C, Pipers F S. Antepartum evaluations of the equine fetus. Journal of Reproduction and Fertility. Supplement 35, 565-573.
  2. Agnew M E, Slack J, Stefanovski D, Linton J K, Sertich P L. Sonographic appearance of the late gestation equine fetal intestine. Theriogenology 138, 121-126.
    doi: 10.1016/j.theriogenology.2019.07.006google scholar: lookup
  3. Albrecht B A, Daels P F. Immunolocalization of 3 beta-hydroxysteroid dehydrogenase, cytochrome P450 17 alpha-hydroxylase/17,20-lyase and cytochrome P450 aromatase in the equine corpus luteum of dioestrus and early pregnancy. Journal of Reproduction and Fertility 111(1), 127-133.
  4. Albrecht B A, MacLeod J N, Daels P F. Differential transcription of steroidogenic enzymes in the equine primary corpus luteum during diestrus and early pregnancy. Biology of Reproduction 56(4), 821-829.
  5. Albrecht B A, MacLeod J N, Daels P F. Expression of 3beta-hydroxysteroid dehydrogenase, cytochrome p450 17alpha-hydroxylase/17,20-lyase and cytochrome p450 aromatase enzymes in corpora lutea of diestrous and early pregnant mares. Theriogenology 55(2), 551-561.
  6. Allen W E. Some observations on pseudopregnancy in mares. The British Veterinary Journal 134(3), 263-269.
    doi: 10.1016/s0007-1935(17)33493-0google scholar: lookup
  7. Allen W R. Factors influencing pregnant mare serum gonadotrophin production. Nature 223(5201), 64-65.
    doi: 10.1038/223064a0google scholar: lookup
  8. Allen W R. The immunological measurement of pregnant mare serum gonadotrophin. The Journal of Endocrinology 43(4), 593-598.
    doi: 10.1677/joe.0.0430593google scholar: lookup
  9. Allen W R. A quantitative immunological assay for pregnant mare serum gonadotrophin. The Journal of Endocrinology 43(4), 581-591.
    doi: 10.1677/joe.0.0430581google scholar: lookup
  10. Allen W R, Moor R M. The origin of the equine endometrial cups. I. Production of PMSG by fetal trophoblast cells. Journal of Reproduction and Fertility 29(2), 313-316.
    doi: 10.1530/jrf.0.0290313google scholar: lookup
  11. Allen W R, Wilsher S. Persistent endometrial cups in the same mare in two successive pregnancies. Equine Veterinary Education 24, 247-250.
  12. Allen W R, Wilsher S, Stewart F, Stewart F, Ousey J, Ousey J, Fowden A. The influence of maternal size on placental, fetal and postnatal growth in the horse. II. Endocrinology of Pregnancy. J Endocrinol 172(2), 237-246.
  13. Antczak D F, de Mestre A M, Wilsher S, Allen W R. The equine endometrial cup reaction: A fetomaternal signal of significance. Annual Review of Animal Biosciences 1, 419-442.
    doi: 10.1146/annurev-animal-031412-103703google scholar: lookup
  14. Astudillo C, Hadjek G, Diaz O. Influencia de algunos factores climaticos sobre la duracion de la gestacion de la yegua Fina Sangre de Carrera. Zoolatria 2(35), 37-38.
  15. Ball B A. Embryonic loss. In A. O. McKinnon, E. L. Squires, W. E. Vaala, & D. D. Varner (Eds.), Equine Reproduction (Vol. 2, 2nd ed., pp. 2327-2338). Wiley-Blackwell..
  16. Bergfelt D R, Pierson R A, Ginther O J. Resurgence of the primary corpus luteum during pregnancy in the mare. Animal Reproduction Science 21, 261-270.
  17. Betteridge K J, Raeside J I, Waelchli R O, Christie H L, Hayes M A. Patterns of conceptus development and of progesterone concentrations in maternal blood preceding spontaneous early pregnancy failure in mares. Reproduction, Fertility, and Development 30(8), 1066-1076.
    doi: 10.1071/rd17336google scholar: lookup
  18. Bhavnani B R. The saga of the ring B unsaturated equine estrogens. Endocrine Reviews 9(4), 396-416.
    doi: 10.1210/edrv-9-4-396google scholar: lookup
  19. Bousfield G R, Liu W K, Sugino H, Ward D N. Structural studies on equine glycoprotein hormones. Amino acid sequence of equine lutropin beta-subunit. The Journal of Biological Chemistry 262(18), 8610-8620.
  20. Brown K A, Dore M, Lussier J G, Sirois J. Human chorionic gonadotropin-dependent up-regulation of genes responsible for estrogen sulfoconjugation and export in granulosa cells of luteinizing preovulatory follicles. Endocrinology 147(9), 4222-4233.
    doi: 10.1210/en.2006-0420google scholar: lookup
  21. Bucca S. Diagnosis of the compromised equine pregnancy. The Veterinary Clinics of North America. Equine Practice 22(3), 749-761.
    doi: 10.1016/j.cveq.2006.07.006google scholar: lookup
  22. Bucca S. Diagnosis of the compromised equine pregnancy. In A. O. McKinnon, E. L. Squires, W. E. Vaala, & D. D. Varner (Eds.), Equine Reproduction (Vol. 1, 2nd ed., pp. 39-54). Wiley Blackwell..
  23. Bucca S. Use of ultrasonography in fetal development and monitoring. In J. A. Kidd, K. G. Lu, & M. L. Frazer (Eds.), Atlas of equine ultrasonography (pp. 383-406). Wiley-Blackwell..
  24. Bucca S, De Oliveira I R S, Cunanan J C, Vinardell T, Troedsson M H T. Doppler indices of the equine fetal carotid artery throughout gestation. Theriogenology 156, 196-204.
    doi: 10.1016/j.theriogenology.2020.07.009google scholar: lookup
  25. Bucca S, Fogarty U. Ultrasonographic cervical parameters throughout gestation in the mare. Proceedings of the American Association of Equine Practitioners 57, 235-241.
  26. Bucca S, Fogarty U, Collins A, Small V. Assessment of feto-placental well-being in the mare from mid-gestation to term: Transrectal and transabdominal ultrasonographic features. Theriogenology 64(3), 542-557.
    doi: 10.1016/j.theriogenology.2005.05.011google scholar: lookup
  27. Canisso I, Beltaire K A, Bedford-Guaus S J. Premature luteal regression in a pregnant mare and subsequent pregnancy maintenance with the use of oral altrenogest. Equine Veterinary Journal 45, 97-100.
  28. Catchpole H R, Lyons W R. The gonad-stimulating hormone of pregnant mares. American Journal of Anatomy 55(2), 167-227.
  29. Chavatte-Palmer P, Duchamp G, Palmer E, Ousey J C, Rossdale P D, Lombes M. Progesterone, oestrogen and glucocorticoid receptors in the uterus and mammary glands of mares from mid- to late gestation. Journal of Reproduction and Fertility. Supplement 56, 661-672.
  30. Cole H H, Hart G H. The potency of blood serum of mares in progressive stages of pregnancy in effecting the sexual maturity of the immature rat. American Journal of Physiology 93, 57-68.
  31. Colles C M, Parkes R D, May C J. Foetal electrocardiography in the mare. Equine Veterinary Journal 10(1), 32-37.
    doi: 10.1111/j.2042-3306.1978.tb02211.xgoogle scholar: lookup
  32. Colon J L. Trans-rectal ultrasonographic appearance of abnormal combined utero-placental thickness in late term gestation and its incidence during routine survey in a population of thoroughbred mares. Proceedings of the American Association of Equine Practitioners 54, 279-285.
  33. Conley A J. Review of the reproductive endocrinology of the pregnant and parturient mare. Theriogenology 86(1), 355-365.
    doi: 10.1016/j.theriogenology.2016.04.049google scholar: lookup
  34. Conley A J. Assessing placental progestogenic support of equine pregnancy - assay for progesterone and the placental progestin, 5α-dihydroprogesterone (DHP). Proceedings of the American Association of Equine Practitioners .
  35. Conley A J, Head J R, Stirling D T, Mason J I. Expression of steroidogenic enzymes in the bovine placenta and fetal adrenal glands throughout gestation. Endocrinology 130(5), 2641-2650.
  36. Coutinho da Silva M A, Canisso I F, MacPherson M L, Johnson A E, Divers T J. Serum amyloid a concentration in healthy periparturient mares and mares with ascending placentitis. Equine Veterinary Journal 45(5), 619-624.
    doi: 10.1111/evj.12034google scholar: lookup
  37. Crabtree J, Chang Y, de Mestre A M. Clinical presentation, treatment and possible causes of persistent endometrial cups illustrated by two cases. Equine Veterinary Education 24(5), 251-259.
  38. Daels P F, Albrecht B A, Mohammed H O. In vitro regulation of luteal function in mares. Reproduction in Domestic Animals 30(4), 211-217.
  39. Daels P F, Albrecht B A, Mohammed H O. Equine chorionic gonadotropin regulates luteal steroidogenesis in pregnant mares. Biology of Reproduction 59(5), 1062-1068.
  40. Daels P F, Ammon D C, Stabenfeldt G H, Liu I K, Hughes J P, Lasley B L. Urinary and plasma estrogen conjugates, estradiol and estrone concentrations in nonpregnant and early pregnant mares. Theriogenology 35(5), 1001-1017.
  41. Daels P F, Chang G C, Hansen B, Mohammed H O. Testosterone secretion during early pregnancy in mares. Theriogenology 45(6), 1211-1219.
  42. Daels P F, DeMoraes J J, Stabenfeldt G H, Hughes J P, Lasley B L. The corpus luteum: Source of oestrogen during early pregnancy in the mare. Journal of Reproduction and Fertility Supplement 44, 501-508.
  43. Daels P F, Shideler S, Lasley B L, Hughes J P, Stabenfeldt G H. Source of oestrogen in early pregnancy in the mare. Journal of Reproduction and Fertility 90(1), 55-61.
  44. Day F T, Rowlands I W. Serum gonadotrophin in welsh and Shetland ponies. The Journal of Endocrinology 5(1), 1-8.
    doi: 10.1677/joe.0.0050001google scholar: lookup
  45. El-Sheikh Ali H, Legacki E L, Scoggin K E, Loux S C, Dini P, Esteller-Vico A, Conley A J, Stanley S D, Ball B A. Steroid synthesis and metabolism in the equine placenta during placentitis. Reproduction 159(3), 289-302.
    doi: 10.1530/rep-19-0420google scholar: lookup
  46. Evans K L, Kasman L H, Hughes J P, Couto M, Lasley B L. Pregnancy diagnosis in the domestic horse through direct urinary estrone conjugate analysis. Theriogenology 22(6), 615-620.
  47. Foss R, Crane A. Serum progesterone changes in embryo transfer recipients. Proceedings of the American Association of Equine Practitioners 50, 521-524.
  48. Fowden A L, Forhead A J, Ousey J C. The endocrinology of equine parturition. Experimental and Clinical Endocrinology & Diabetes 116(7), 393-403.
    doi: 10.1055/s-2008-1042409google scholar: lookup
  49. Fraser A F, Keith N W, Hastie H. Summarized observations on the ultrasonic detection of pregnancy and fetal life in the mare. Veterinary Record 92, 20-21.
  50. Ginther O J. Embryonic loss in mares: Incidence, time of occurrence, and hormonal involvement. Theriogenology 23(1), 77-89.
  51. Ginther O J. Equine pregnancy: Physical interactions between the uterus and conceptus. Proceedings of the American Association of Equine Practitioners 44, 73-104.
  52. Hartwig F C, Antunez L, Dos Santos R S, Lisboa F P, Machado Pfeifer L F, Wayne Nogueira C E, da Rosa Curcio B. Determining the gestational age of Crioulo mares based on a fetal ocular measure. Journal of Equine Veterinary Science 33, 557-560.
  53. Heap R B, Hamon M, Allen W R. Studies on oestrogen synthesis by the preimplantation equine conceptus. Journal of Reproduction and Fertility. Supplement 32, 343-352.
  54. Heap R B, Hamon M H, Allen W R. Oestrogen production by the preimplantation donkey conceptus compared with that of the horse and the effect of between-species embryo transfer. Journal of Reproduction and Fertility 93(1), 141-147.
  55. Hendriks W K, Colenbrander B, van der Weijden G C, Stout T A. Maternal age and parity influence ultrasonographic measurements of fetal growth in Dutch warmblood mares. Animal Reproduction Science 115(1-4), 110-123.
    doi: 10.1016/j.anireprosci.2008.12.014google scholar: lookup
  56. Hershman L, Douglas R H. The critical period for the maternal recognition of pregnancy in pony mares. Journal of Reproduction and Fertility Supplement (27), 395-401.
  57. Hodge S L, Kreider J L, Potter G D, Harms P G, Fleeger J L. Influence of photoperiod on the pregnant and postpartum mare. American Journal of Veterinary Research 43(10), 1752-1755.
  58. Hoffmann B, Gentz F, Failing K. Investigations into the course of progesterone, oestrogen and eCG concentrations during normal and impaired pregnancy in the mare. Reproduction in Domestic Animals 31, 717-723.
  59. Hollinshead F K, Mehegan M K, Gunn A, Nett T, Bruemmer J E, Hanlon D W. The correlation of endogenous progesterone concentration in diestrus on early pregnancy rate in thoroughbred mares. Journal of Equine Veterinary Science 118, 104127.
    doi: 10.1016/j.jevs.2022.104127google scholar: lookup
  60. Holtan D W, Houghton E, Silver M, Fowden A L, Ousey J, Rossdale P D. Plasma progestagens in the mare, fetus and newborn foal. Journal of Reproduction and Fertility. Supplement 44, 517-528.
  61. Holtan D W, Nett T M, Estergreen V L. Plasma progestins in pregnant, postpartum and cycling mares. Journal of Animal Science 40(2), 251-260.
  62. Holtan D W, Squires E L, Lapin D R, Ginther O J. Effect of ovariectomy on pregnancy in mares. Journal of Reproduction and Fertility. Supplement 27, 457-463.
  63. Huber M J, Roser J F, Riebold T W, Schmotzer W B, Grubb T L, Crisman R O. Effect of surgical removal of endometrial cups on concentrations of chorionic gonadotrophin and subsequent fertility in the mare. Equine Veterinary Journal 25(2), 110-114.
    doi: 10.1111/j.2042-3306.1993.tb02918.xgoogle scholar: lookup
  64. Hyland J H, Langstrom B. Changes in urinary and plasma oestrone sulphate concentrations after induction of foetal death in mares at 45 days of gestation. Australian Veterinary Journal 67(10), 349-351.
  65. Hyland J H, Wright P J, Manning S J. An investigation of the use of plasma oestrone sulphate concentrations for the diagnosis of pregnancy in mares. Australian Veterinary Journal 61(4), 123.
  66. Irvine C H G, Sutton P, Turner J E, Mennick P E. Changes in plasma progesterone concentrations from days 17 to 42 of gestation in mares maintaining or losing pregnancy. Equine Veterinary Journal 22(2), 104-106.
  67. Jeffcott L B, Hyland J H, MacLean A A, Dyke T, Robertson-Smith G. Changes in maternal hormone concentrations associated with induction of fetal death at day 45 of gestation in mares. Journal of Reproduction and Fertility Supplement 35, 461-467.
  68. Jewgenow K, Meyer H H. Comparative binding affinity study of progestins to the cytosol progestin receptor of endometrium in different mammals. General and Comparative Endocrinology 110(2), 118-124.
  69. Kahn W, Leidl W. Ultrasonic biometry of horse fetuses in utero and sonographic representation of their organs. Deutsche Tierärztliche Wochenschrift 94(9), 509-515.
  70. Kasman L H, Hughes J P, Stabenfeldt G H, Starr M D, Lasley B L. Estrone sulfate concentrations as an indicator of fetal demise in horses. American Journal of Veterinary Research 49(2), 184-187.
  71. Kasman L H, Stabenfeldt G H, Hughes J P, Couto M, Lasley B L. Circulating oestrone sulphate concentrations in pregnant mares undergoing ovariectomy. Journal of Reproduction & Fertility Supplement 35, 721-723.
  72. Kelleman A A. Equine pregnancy and clinical applied physiology. Proceedings of the American Association of Equine Practitioners 59, 350-358.
  73. Kimura Y, Haneda S, Aoki T, Furuoka H, Miki W, Fukumoto N, Matsui M, Nambo Y. Combined thickness of the uterus and placenta and ultrasonographic examinations of uteroplacental tissues in normal pregnancy, placentitis, and abnormal parturitions in heavy draft horses. Journal of Equine Science 29(1), 1-8.
    doi: 10.1294/jes.29.1google scholar: lookup
  74. Kindahl H, Knudsen O, Madej A, Edqvist L E. Progesterone, prostaglandin F2alpha, PMSG and oestrone sulphate during early pregnancy in the mare. Journal of Reproduction and Fertility Supplement 32, 353-359.
  75. Klein C, Troedsson M H. Maternal recognition of pregnancy in the horse: A mystery still to be solved. Reproduction, Fertility, and Development 23(8), 952-963.
    doi: 10.1071/rd10294google scholar: lookup
  76. Klewitz J, Struebing C, Rohn K, Goergens A, Martinsson G, Orgies F, Probst J, Hollinshead F, Bollwein H, Sieme H. Effects of age, parity, and pregnancy abnormalities on foal birth weight and uterine blood flow in the mare. Theriogenology 83(4), 721-729.
    doi: 10.1016/j.theriogenology.2014.11.007google scholar: lookup
  77. Lanci A, Castagnetti C, Ranciati S, Sergio C, Mariella J. A regression model including fetal orbit measurements to predict parturition in Standardbred mares with normal pregnancy. Theriogenology 126, 153-158.
    doi: 10.1016/j.theriogenology.2018.12.020google scholar: lookup
  78. LeBlanc M M. Ascending placentitis in the mare: An update. Reproduction in Domestic Animals 45(Suppl 2), 28-34.
    doi: 10.1111/j.1439-0531.2010.01633.xgoogle scholar: lookup
  79. Legacki E L, Ball B A, Corbin C J, Loux S C, Stanley S D, Conley A J. Equine fetal adrenal, gonadal and placental steroidogenesis. Reproduction 54(4), 445-454.
  80. Legacki E L, Corbin C J, Ball B A, Scoggin K E, Stanley S D, Conley A J. Steroidogenic enzyme activities in the pre- and post-parturient equine placenta. Reproduction 155(1), 51-59.
    doi: 10.1530/rep-17-0472google scholar: lookup
  81. Legacki E L, Corbin C J, Ball B A, Wynn M, Loux S, Stanley S D, Conley A J. Progestin withdrawal at parturition in the mare. Reproduction 152(4), 323-331.
    doi: 10.1530/rep-16-0227google scholar: lookup
  82. Legacki E L, Scholtz E L, Ball B A, Stanley S D, Berger T, Conley A J. Concentrations of sulphated estrone, estradiol and dehydroepiandrosterone measured by mass spectrometry in pregnant mares. Equine Veterinary Journal 51, 802-808.
    doi: 10.1111/evj.13109google scholar: lookup
  83. Legacki E L, Scholtz E L, Ball B A, Stanley S D, Conley A J. The dynamic steroid landscape of equine pregnancy mapped by mass spectrometry. Reproduction 151(4), 421-430.
    doi: 10.1530/rep-15-0547google scholar: lookup
  84. Loux S, Robles M, Chavatte-Palmer P, de Mestre A. Markers of equine placental differentiation: Insights from gene expression studies. Reproduction 163(3), R39-R54.
    doi: 10.1530/rep-21-0115google scholar: lookup
  85. Loux S C, Conley A J, Scoggin K E, El-Sheikh Ali H, Dini P, Ball B A. New insights in equine steroidogenesis: An in-depth look at steroid signaling in the placenta. Reproduction 160(1), 65-82.
    doi: 10.1530/rep-20-0015google scholar: lookup
  86. Lund J, Mason J I, Simpson E R, Waterman M R. Developmental regulation of P-45017 alpha gene expression in fetal bovine adrenal. Endocrine Research 15(1-2), 17-29.
  87. Manning A W, Rajkumar K, Bristol F, Flood P F, Murphy B D. Genetic and temporal variation in serum concentrations and biological activity of horse chorionic gonadotrophin. Journal of Reproduction and Fertility. Supplement 35, 389-397.
  88. Manning F A. The fetal biophysical profile score: Current status. Obstetrics and Gynecology Clinics of North America 17(1), 147-162.
  89. McCaughey W J, Hanna J, O'Brien J J. A comparison of three laboratory tests for pregnancy diagnosis in the mare. Equine Veterinary Journal 5(2), 94-95.
    doi: 10.1111/j.2042-3306.1973.tb03202.xgoogle scholar: lookup
  90. McGladdery A, Ousey J. Vascular impedance of the umbilical cord artery during equine pregnancy. Equine Veterinary Journal 48, 10-11.
  91. McKinnon A O, Squires E L, Carnevale E M, Hermenet M J. Ovariectomized steroid-treated mares as embryo transfer recipients and as a model to study the role of progestins in pregnancy maintenance. Theriogenology 29(5), 1055-1063.
    doi: 10.1016/s0093-691x(88)80029-3google scholar: lookup
  92. McRobb L, Handelsman D J, Kazlauskas R, Wilkinson S, McLeod M D, Heather A K. Structure-activity relationships of synthetic progestins in a yeast-based in vitro androgen bioassay. The Journal of Steroid Biochemistry and Molecular Biology 110(1-2), 39-47.
    doi: 10.1016/j.jsbmb.2007.10.008google scholar: lookup
  93. Mitchell D. Early fetal death and a serum gonadotrophin test for pregnancy in the mare. The Canadian Veterinary Journal 12(2), 41-44.
  94. Moor R M, Allen W R, Hamilton D W. Origin and histogenesis of equine endometrial cups. Journal of Reproduction and Fertility Supplement (23), 391-395.
  95. Murphy B D, Martinuk S D. Equine chorionic gonadotropin. Endocrine Reviews 12(1), 27-44.
    doi: 10.1210/edrv-12-1-27google scholar: lookup
  96. Naden J, Squires E L, Nett T M. Effect of maternal treatment with altrenogest on age at puberty, hormone concentrations, pituitary response to exogenous GnRH, oestrous cycle characteristics and fertility of fillies. Journal of Reproduction and Fertility 88(1), 185-195.
  97. Newcombe J R. Spontaneous oestrous behaviour during pregnancy associated with luteal regression, ovulation and birth of a live foal in a part thoroughbred mare. Equine Veterinary Education 12(2), 85-87.
  98. Ousey J C, Forhead A J, Rossdale P D, Grainger L, Houghton E, Fowden A L. Ontogeny of uteroplacental progestagen production in pregnant mares during the second half of gestation. Biology of Reproduction 69(2), 540-548.
  99. Ousey J C, Houghton E, Grainger L, Rossdale P D, Fowden A L. Progestagen profiles during the last trimester of gestation in thoroughbred mares with normal or compromised pregnancies. Theriogenology 63(7), 1844-1856.
  100. Ousey J C, Kolling M, Kindahl H, Allen W R. Maternal dexamethasone treatment in late gestation induces precocious fetal maturation and delivery in healthy thoroughbred mares. Equine Veterinary Journal 43(4), 424-429.
    doi: 10.1111/j.2042-3306.2010.00306.xgoogle scholar: lookup
  101. Palmer J. Fetal monitoring. In Paper presented at the annual conference Society for Theriogenology. Society for Theriogenology..
  102. Pashen R L, Sheldrick E L, Allen W R, Flint A P. Dehydroepiandrosterone synthesis by the fetal foal and its importance as an oestrogen precursor. Journal of Reproduction and Fertility Supplement 32, 389-397.
  103. Penzhorn B L, Bertschinger H J, Coubrough R I. Reconception of mares following termination of pregnancy with prostaglandin F2 alpha before and after day 35 of pregnancy. Equine Veterinary Journal 18(3), 215-217.
    doi: 10.1111/j.2042-3306.1986.tb03602.xgoogle scholar: lookup
  104. Podico G, Canisso I F, Roady P J, Austin S M, Carossino M, Balasuriya U, Ellerbrock R E, Lima F S, Ferreira-Dias G, Douglas R H. Uterine responses and equine chorionic gonadotropin concentrations after two intrauterine infusions with kerosene post early fetal loss in mares. Theriogenology 147, 202-210.
    doi: 10.1016/j.theriogenology.2019.11.014google scholar: lookup
  105. Powel D. Mare reproductive loss syndrome. In A. O. McKinnon, E. L. Squires, W. E. Vaala, & D. D. Varner (Eds.), Equine Reproduction (Vol. 2, pp. 2410-2417). Wiley-Blackwell..
  106. Raeside J I. A brief account of the discovery of the fetal/placental unit for estrogen production in equine and human pregnancies: Relation to human medicine. The Yale Journal of Biology and Medicine 90(3), 449-461.
  107. Rantanen N W, Kincaid B. Ultrasound guided fetal cardiac puncture: A method of twin reduction in the mare. Proceedings of the American Association of Equine Practitioners 44, 173-179.
  108. Rathwell A C, Asbury A C, Hansen P J, Archbald L F. Reproductive function of mares given daily injections of prostaglandin F2alpha beginning at day 42 of pregnancy. Theriogenology 27(4), 621-630.
    doi: 10.1016/0093-691x(87)90056-2google scholar: lookup
  109. Reef V B, Vaala W, Worth L, Spencer P A, Hammet B. Ultrasonographic evaluation of the fetus and intrauterine environment in healthy mares during late gestation. Veterinary Radiology & Ultrasound 36, 533-541.
  110. Reef V B, Vaala W E, Worth L T, Sertich P L, Spencer P A. Ultrasonographic assessment of fetal well-being during late gestation: Development of an equine biophysical profile. Equine Veterinary Journal 28(3), 200-208.
    doi: 10.1111/j.2042-3306.1996.tb03773.xgoogle scholar: lookup
  111. Renaudin C D. Evaluation échographique du foetus équin par voie transabdominale. Proceeding Journées Nationales Des GTV 381-382.
  112. Renaudin C D. Transrectal ultrasonographic diagnosis of ascending placentitis in the mare: A report of two cases. Equine Veterinary Education 11, 69-74.
  113. Renaudin C D. Evaluation échographique de la jument gravide par voie transabdominale. In Proceedings Congress AVEF (44th ed., pp. 24-25). AVEF Annual Congress..
  114. Renaudin C D. Evaluation and monitoring of the pregnant mare. In L. L. R. Costa & M. R. Paradis (Eds.), Manual of clinical procedures in the horse (1st ed., pp. 370-383). Wiley-Blackwell..
  115. Renaudin C D. Fetal ultrasonography of the first phalange: A new tool to assess fetal growth and bone development. Proceedings of the American Association of Equine Practitioners 67, 264-265.
  116. Renaudin C D, Gillis C L, Tarantal A F, Coleman D A. Evaluation of equine fetal growth from day 100 of gestation to parturition by ultrasonography. Journal of Reproduction and Fertility Supplement (56), 651-660.
  117. Renaudin C D, Kass P H, Bruyas J F. Prediction of gestational age based on foetal ultrasonographic biometric measurements in light breed horses. Reproduction in Domestic Animals 57(7), 743-753.
    doi: 10.1111/rda.14116google scholar: lookup
  118. Renaudin C D, Troedssen M H T. Transrectal ultrasonographic evaluation of the normal equine placenta. Equine Veterinary Education 15, 16-17.
  119. Renaudin C D, Troedsson M H, Gillis C L, King V L, Bodena A. Ultrasonographic evaluation of the equine placenta by transrectal and transabdominal approach in the normal pregnant mare. Theriogenology 47(2), 559-573.
    doi: 10.1016/s0093-691x(97)00014-9google scholar: lookup
  120. Renaudin C D, Wensley F, Morgan J, Cassano J, Spriet M. Fetal ultrasonography of the distal limb: a new tool to assess equine fetal age and bone maturation. Proceedings ISER XIII, in press .
  121. Richards C B. Simple immunological method for the diagnosis of pregnancy in mares. Nature 215(5107), 1280-1281.
    doi: 10.1038/2151280a0google scholar: lookup
  122. Robertson H A, Dwyer R J, King G J. Oestrogens in fetal and maternal fluids throughout pregnancy in the pig and comparisons with the ewe and cow. The Journal of Endocrinology 106(3), 355-360.
  123. Robertson H A, King G J. Plasma concentrations of progesterone, oestrone, oestradiol-17beta and of oestrone sulphate in the pig at implantation, during pregnancy and at parturition. Journal of Reproduction and Fertility 40(1), 133-141.
  124. Rossdale P D, McGladdery A J, Ousey J C, Holdstock N, Grainger L, Houghton E. Increase in plasma progestagen concentrations in the mare after foetal injection with CRH, ACTH or betamethasone in late gestation. Equine Veterinary Journal 24(5), 347-350.
  125. Satué K, Felipe M, Mota J, Muñoz A. Factors influencing gestational length in mares: A review. Livestock Science 136, 287-294.
  126. Scholtz E L, Krishnan S, Ball B A, Corbin C J, Moeller B C, Stanley S D, McDowell K J, Hughes A L, McDonnell D P, Conley A J. Pregnancy without progesterone in horses defines a second endogenous biopotent progesterone receptor agonist, 5α-dihydroprogesterone. Proceedings of the National Academy of Sciences of the United States of America 111(9), 3365-3370.
    doi: 10.1073/pnas.1318163111google scholar: lookup
  127. Sertich P L. Clinical anatomy and evaluation of equine fetal membranes. Proceedings of the Annual Meeting Society of Theriogenology 46, 178-184.
  128. Shackleton C H, Roitman E, Kratz L E, Kelley R I. Equine type estrogens produced by a pregnant woman carrying a Smith-Lemli-Opitz syndrome fetus. The Journal of Clinical Endocrinology and Metabolism 84(3), 1157-1159.
    doi: 10.1210/jcem.84.3.5660google scholar: lookup
  129. Sherman G B, Wolfe M W, Farmerie T A, Clay C M, Threadgill D S, Sharp D C, Nilson J H. A single gene encodes the beta-subunits of equine luteinizing hormone and chorionic gonadotropin. Molecular Endocrinology 6(6), 951-959.
    doi: 10.1210/mend.6.6.1379674google scholar: lookup
  130. Shideler R K, Squires E L, Voss J L, Eikenberry D J, Pickett B W. Progestagen therapy of ovariectomized pregnant mares. Journal of Reproduction and Fertility. Supplement 32, 459-464.
  131. Shorten P R, Legacki E L, Chavatte-Palmer P, Conley A J. Algorithms predicting gestational stage from the maternal steroid metabolome of mares. The Journal of Endocrinology 252(1), 45-57.
    doi: 10.1530/joe-21-0249google scholar: lookup
  132. Slovis N, Lu K G, Wolfsdorf K, Zent W. How to manage hydrops allantois/hydrops amnion in a mare. Proceedings of the American Association of Equine Practitioners 59, 34-39.
  133. Souza A M, Winter G H Z, Garbade P, Wolf C A, Jobim M I M, Gregory R M, Mattos R C. Ultrasonographic evaluation of the Criollo mare placenta. Animal Reproduction Science 121, S320-S321.
  134. Squires E L, Ginther O J. Follicular and luteal development in pregnant mares. Journal of Reproduction and Fertility Supplement 23, 429-433.
  135. Squires E L, Hillman R B, Pickett B W, Nett T M. Induction of abortion in mares with equimate: Effect on secretion of progesterone, PMSG and reproductive performance. Journal of Animal Science 50(3), 490-495.
    doi: 10.2527/jas1980.503490xgoogle scholar: lookup
  136. Stewart F, Allen W R. Biological functions and receptor binding activities of equine chorionic gonadotrophins. Journal of Reproduction and Fertility 62(2), 527-536.
    doi: 10.1530/jrf.0.0620527google scholar: lookup
  137. Sugino H, Bousfield G R, Moore W T Jr, Ward D N. Structural studies on equine glycoprotein hormones. Amino acid sequence of equine chorionic gonadotropin beta-subunit. The Journal of Biological Chemistry 262(18), 8603-8609.
  138. Swegen A. Maternal recognition of pregnancy in the mare: Does it exist and why do we care?. Reproduction 161(6), R139-R155.
    doi: 10.1530/rep-20-0437google scholar: lookup
  139. Tait A D, Hodge L C, Allen W R. The biosynthesis of 3beta-hydroxy-5,7-androstadien-17-one by the horse fetal gonad. FEBS Letters 182(1), 107-110.
    doi: 10.1016/0014-5793(85)81164-9google scholar: lookup
  140. Tait A D, Santikarn S, Allen W R. Identification of 3beta-hydroxy-5,7-pregnadien-20-one and 3beta-hydroxy-5,7-androstadien-17-one as endogenous steroids in the fetal horse gonad. The Journal of Endocrinology 99(1), 87-92.
  141. Tangalakis K, Crawford R, McFarlane A C, Wintour E M. Regulation of steroid hydroxylase gene expression in the ovine fetal adrenal gland at 0.4 gestation. Molecular and Cellular Endocrinology 103(1-2), 21-27.
  142. Terqui M, Palmer E. Oestrogen pattern during early pregnancy in the mare. Journal of Reproduction and Fertility. Supplement 27, 441-446.
  143. Troedssen M H T, Macpherson M L. Placentitis. In A. O. McKinnon, E. L. Squires, W. Vaala, & D. D. Varner (Eds.), Equine Reproduction (Vol. 2, 2nd ed., pp. 2359-2367). Wiley-Blackwell..
  144. Troedssen M H T, Renaudin C D, Zent W, Steiner J V. Transrectal ultrasonography of the placenta in normal mares and mares with pending abortion: A field study. Proceedings of the American Association of Equine Practitioners 43, 256-258.
  145. Turner R M, McDonnell S M, Feit E M, Grogan E H, Foglia R. Real-time ultrasound measure of the fetal eye (vitreous body) for prediction of parturition date in small ponies. Theriogenology 66(2), 331-337.
    doi: 10.1016/j.theriogenology.2005.11.019google scholar: lookup
  146. Uhl E W. The pathology of vitamin D deficiency in domesticated animals: An evolutionary and comparative overview. International Journal of Paleopathology 23, 100-109.
    doi: 10.1016/j.ijpp.2018.03.001google scholar: lookup
  147. Vaala W E, Sertich P L. Management strategies for mares at risk for periparturient complications. The Veterinary Clinics of North America. Equine Practice 10(1), 237-265.
    doi: 10.1016/s0749-0739(17)30376-0google scholar: lookup
  148. Vincze B, Baska F, Papp M, Szenci O. Introduction of a new fetal examination protocol for on-field and clinical equine practice. Theriogenology 125, 210-215.
    doi: 10.1016/j.theriogenology.2018.11.004google scholar: lookup
  149. Walker D. Laboratory methods of equine pregnancy diagnosis. Veterinary Record 100, 396-399.
  150. Wesson J A, Ginther O J. Fetal and maternal gonads and gonadotropins in the pony. Biology of Reproduction 22(4), 735-743.
  151. Wide M, Wide L. Diagnosis of pregnancy in mares by an immunological method. Nature 198, 1017-1018.
    doi: 10.1038/1981017a0google scholar: lookup
  152. Wilsher S, Allen W R. Factors influencing equine chorionic gonadotrophin production in the mare. Equine Veterinary Journal 43(4), 430-438.
    doi: 10.1111/j.2042-3306.2010.00309.xgoogle scholar: lookup
  153. Wynn M A A, Esteller-Vico A, Legacki E L, Conley A J, Loux S C, Stanley S D, Curry T E Jr, Squires E L, Troedsson M H, Ball B A. A comparison of progesterone assays for determination of peripheral pregnane concentrations in the late pregnant mare. Theriogenology 106, 127-133.
    doi: 10.1016/j.theriogenology.2017.10.002google scholar: lookup

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