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Ultrasonographic evaluation of the equine placenta by transrectal and transabdominal approach in the normal pregnant mare.
Abstract: The objective of this study was to determine normal variations in the utero placental thickness during mid- and late gestation in the mare. Normal, healthy pregnant mares (n = 9) were examined monthly from 4 mo of gestation until parturition by transrectal and transabdominal ultrasonography. At each examination, the combined thickness of the uterus and the placenta (CTUP) was measured at the placento-cervical junction (transrectally) and at the uterine body or the uterine horns (transabdominally). In addition, the echogenicity of the amniotic and allantoic fluids was evaluated by transrectal ultrasonography. Following parturition and expulsion of the fetal membranes, the allantochorion was measured and visually examined for abnormalities. At all examinations, both transrectal and transabdominal, the chorioallantois and the uterus were indistinguishable from each other on the ultrasound image. The CTUP, measured by transrectal ultrasonography did not change between 4 and 8 mo of gestation, but increased significantly for each month between 10 and 12 mo of gestation (P < 0.001). A change in the CTUP was detected between months when measured by transabdominal ultrasonography, but no distinct pattern in these changes was observed. No correlation was found between transabdominal and transrectal measurements of the CTUP. The echogenicity of the amniotic and allantoic fluids did not consistently change over time during mid- and late gestation. The amniotic fluid was more echogenic than the allantoic fluid at most examinations from 6 mo of pregnancy and throughout gestation (P < 0.05). It was concluded that transrectal ultrasonographic examination to assess the CTUP and the echogenicity of the fetal fluids is superior to the transabdominal approach. We suggest that transrectal ultrasonographic examination should be added to current diagnostic tools during late gestation and that it be part of the biophysical profile of high risk equine pregnancies.
Publication Date: 1997-01-15 PubMed ID: 16728008DOI: 10.1016/s0093-691x(97)00014-9Google 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
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 investigates the changes in thickness and fluid echogenicity of the equine placenta using two methods: transrectal and transabdominal ultrasonography. The main finding is that transrectal examination is a better method to assess these conditions during the middle and late stages of gestation.
Objective of the Study
- The goal of this study was to observe and understand the standard variations in the utero placental thickness during mid- and late gestation in horses. The researchers were particularly interested in comparing the efficacy of two different ultrasound techniques: transrectal and transabdominal.
Methodology
- The study was conducted on healthy, pregnant mares (n = 9). These mares were examined once a month from the fourth month of gestation until birth.
- Both transrectal and transabdominal ultrasonography were used to measure the combined thickness of the uterus and placenta (CTUP).
- Additionally, the echogenicity (or the ability to bounce back ultrasound waves) of the amniotic and allantoic fluids was studied using transrectal ultrasonography.
Results
- The CTUP did not show any change from months 4 to 8. However, from months 10 to 12, there was a significant increase in the CTUP.
- On the other hand, while changes in CTUP were detected with transabdominal ultrasonography, no distinct pattern for these changes was identified.
- Additionally, no correlation was found between the CTUP measurements taken transabdominally and those taken transrectally.
- The echogenicity of the amniotic and allantoic fluids did not change consistently over time during mid- and late gestation.
Conclusion
- The researchers concluded that transrectal ultrasonographic examination is higher quality for measuring CTUP and assessing the echogenicity of fetal fluids compared to the transabdominal approach.
- The study suggests that the transrectal ultrasonographic examination should be included in the current diagnostic tools during late gestation and be part of the biophysical profile of high risk equine pregnancies.
Cite This Article
APA
Renaudin CD, Troedsson MH, Gillis CL, King VL, Bodena A.
(1997).
Ultrasonographic evaluation of the equine placenta by transrectal and transabdominal approach in the normal pregnant mare.
Theriogenology, 47(2), 559-573.
https://doi.org/10.1016/s0093-691x(97)00014-9 Publication
Researcher Affiliations
- Department of Equine Reproduction, Veterinary Medical Teaching Hospital, University of California, Davis, CA 95616, USA.
Citations
This article has been cited 15 times.- Scoggin KE, Rakha SI, Abdellatif AM, Adlan F, Helmy YA, Ruby R, Ball B, Boakari Y, Ali HE. Activation of the S100A8/A9 Alarmin Amplifies Inflammatory Pathways in Equine Ascending Placentitis. Int J Mol Sci 2026 Feb 4;27(3).
- Hardefeldt L, Thomas K, Page S, Norris J, Browning G, El Hage C, Stewart A, Gilkerson J, Muscatello G, Verwilghen D, van Galen G, Bauquier J, Cuming R, Reynolds B, Whittaker C, Wilkes E, Clulow J, Burden C, Begg L. Antimicrobial prescribing guidelines for horses in Australia. Aust Vet J 2025 Dec;103(12):781-889.
- Marchio SP, El-Sheikh Ali H, Scott MA, Barbosa Fernandes C, Scoggin KE, Troedsson M, Boakari Y. Decoding the amniotic membrane transcriptome during equine ascending placentitis. Sci Rep 2025 Aug 21;15(1):30714.
- Peere S, Van den Branden E, Broothaers K, Polfliet E, Smits K, Govaere J. Birth of a Healthy Monozygotic Twin Foal with Hydrops and a Dead Co-Twin. Vet Sci 2024 Dec 13;11(12).
- Morales-Vázquez MM, Meza-Serrano E, Lara-Pereyra I, Acuña-González RJ, Alonso-Morales R, Hayen-Valles S, Boeta AM, Zarco L, Lozano-Cuenca J, López-Canales JS, Flores-Herrera H. Equine Placentitis in Mares Induces the Secretion of Pro-Inflammatory Cytokine eIL-1β and the Active Extracellular Matrix Metalloproteinase (MMP)-9. Vet Sci 2023 Aug 22;10(9).
- Fedorka CE, Ali HE, Troedsson MHT. Galectins in Equine Placental Disease. Vet Sci 2023 Mar 13;10(3).
- Abdelnaby EA, Emam IA, El-Sherbiny HR, Fadl AM. The effects of aging and gestational month on uteroplacental vascular perfusion, and umbilical artery hemodynamics in pregnant jennies. BMC Vet Res 2022 Nov 15;18(1):404.
- Lanci A, Perina F, Donadoni A, Castagnetti C, Mariella J. Dystocia in the Standardbred Mare: A Retrospective Study from 2004 to 2020. Animals (Basel) 2022 Jun 8;12(12).
- Gao Y, Hannan MA, Murata K, Rajabi-Toustani R, Nambo Y. Ultrasonographic examination of equine fetal growth parameters throughout gestation in pony for Equine-Assisted Therapy. J Vet Med Sci 2022 Jan 7;84(1):74-81.
- Cruz-Aleixo AS, Lima MCF, Albuquerque ALH, Teixeira RT, Paula RA, Grandi MC, Ferreira DOL, Tsunemi MH, Chiacchio SB, Lourenço MLG. Echocardiographic evaluation in Dorper ovine fetuses: Applications and limitations. Vet Med Sci 2021 Mar;7(2):417-423.
- Mitchell ARM, Delvescovo B, Tse M, Crouch EE, Cheong SH, Castillo JM, Felippe MJB, Ainsworth DM, de Amorim MD. Successful management of hydrallantois in a Standardbred mare at term resulting in the birth of a live foal. Can Vet J 2019 May;60(5):495-501.
- 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. J Equine Sci 2018;29(1):1-8.
- Murase H, Niwa H, Katayama Y, Sato F, Hada T, Nambo Y. A clinical case of equine fungal placentitis with reference to hormone profiles and ultrasonography. J Equine Sci 2015;26(4):129-33.
- Murase H, Endo Y, Tsuchiya T, Kotoyori Y, Shikichi M, Ito K, Sato F, Nambo Y. Ultrasonographic evaluation of equine fetal growth throughout gestation in normal mares using a convex transducer. J Vet Med Sci 2014 Jul;76(7):947-53.
- Cummins C, Carrington S, Fitzpatrick E, Duggan V. Ascending placentitis in the mare: A review. Ir Vet J 2008 May 1;61(5):307-13.
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