Early pregnancy loss in a mare due to possible acute uterine bacterial infection
Keywords:
Mare, endometritis, acute bacterial infection, early embryonic loss, treatment
Abstract
This case involves an 11-year Haflinger mare with breeding induced endometritis. After breeding soundness examination, mare was inseminated twice during 1 estrous cycle. On day 1 (day 0 = day of ovulation), mare was negative for endometrial cytology and culture. On day 10, an embryonic vesicle was visualized via transrectal ultrasonography; progesterone concentrations were 15.8 ng/ml. On day 11, the embryonic vesicle had increased to a diameter of 0.8 cm with clearly visible endometrial edema; progesterone concentrations were 14.4 ng/ml. On day 12, embryonic vesicle was no longer visible; progesterone concentrations were 4.7 ng/ml (possibility of premature luteolysis). Bacteriological culture of the uterus with a guarded endometrial swab had a pure culture of Streptococcus equi subspecies zooepidemicus (S. zooepidemicus). Mare underwent treatment (uterine lavage and systemic penicillin for 5 days) and became pregnant at the next estrus. This case highlighted the possibility of S. zooepidemicus subclinical endometrial infection, not diagnosed by routine endometrial cytology and culture, becoming dormant.
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References
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23. Nielsen JM, Nielsen FH, Petersen MR, et al: Diagnosis of equine endometritis–Microbiology, cytology and histology of endometrial biopsies and the correlation to fertility. Pferdeheilkunde 2012;28:8–13.
24. LeBlanc MM: Advances in the diagnosis and treatment of chronic infectious and post-mating-induced endometritis in the mare. Reprod Dom Anim 2010;45:21–27. doi: 10.1111/j.1439-0531.2010.01634.x
25. Christoffersen M, Brandis L, Samuelsson J, et al: Diagnostic double-guarded low-volume uterine lavage in mares. Theriogenology 2015;83:222–227. doi: 10.1016/j.theriogenology.2014.09.008
26. Von Dollen K, Lu K, Lyle S, et al: Clinical observations of bacterial culture results after intrauterine infusion of misoprostol. Clinical Theriogenology 2022;14:301.
27. Nielsen JM: Endometritis in the mare: a diagnostic study comparing cultures from swab and biopsy. Theriogenology 2005;64:510–518. doi: 10.1016/j.theriogenology.2005.01.008
28. Aurich C, Budik S: Season does not influence embryo recovery rate and conceptus size until day 14 after ovulation in the horse. Reprod Dom Anim 2015;50:299–303. doi: 10.1111/rda.12490
29. Vanderwall DK, Squires EL, Brinsko SP, et al: Diagnosis and management of abnormal embryonic development characterized by formation of an embryonic vesicle without an embryo in mares. J Am Vet Med Assoc 2000;217:58–63. doi: 10.2460/javma.2000.217.58
30. McCue PM: Ultrasound examination of the pregnant reproductive tract. In: Descanio J, McCue P: editors. Equine Reproductive Procedures. 2nd edition, Amess; Wiley Blackwell: 2021. p. 257–261.
31. Ferris R: Biofilm and latent bacteria in equine uterus. Clinical Theriogenology 2022;14:229-232. doi: 10.58292/ct.v14.9680
2. Wilsher S: The uterus and early pregnancy failure in the mare. Equine Vet Educ 2019;31:214-224. doi: 10.1111/eve.12844
3. Newcombe JR, Cuervo-Arango J: The relationship between the positive identification of the embryo proper in equine pregnancies aged 18–28 days and its future viability: a field study. J Equine Vet Sci 2012;32:257–261. doi: 10.1016/j.jevs.2011.09.068
4. Pascottini OB, Aurich C, England G, et al: General and comparative aspects of endometritis in domestic species: a review. Reprod Dom Anim 2023;58:49–71. doi: 10.1111/rda.14390
5. Morris LH, McCue PM, Aurich C: Equine endometritis: a review of challenges and new approaches. Reproduction 2020;160: R95–R110. doi: 10.1530/REP-19-0478
6. Morris LH, Allen WR: Reproductive efficiency of intensively managed Thoroughbred mares in Newmarket. Equine Vet J 2002;34: 51–60. doi: 10.2746/042516402776181222
7. Nocera FP, D’Eletto E, Ambrosio M, et al: Occurrence and antimicrobial susceptibility profiles of Streptococcus equi subsp. zooepidemicus strains isolated from mares with fertility problems. Antibiotics 2021;11:25. doi: 10.3390/antibiotics11010025
8. Cerny KL, Little TV, Scoggin CF, et al: Presence of bacteria on the external genitalia of healthy stallions and its transmission to the mare at the time of breeding by live cover. J Equine Vet Sci 2014;34:369–374. doi: 10.1016/j.jevs.2013.07.008
9. LeBlanc MM, Causey RC: Clinical and subclinical endometritis in the mare: both threats to fertility. Reprod Dom Anim 2009;44: 10–22. doi: 10.1111/j.1439-0531.2009.01485.x
10. Köhne M, Hegger A, Tönissen A, et al: Frequency of potentially pathogenic bacterial and fungal isolates among 28,887 endometrial samples from mares, with an emphasis on multi-drug resistant bacteria in Germany (2018–2022). J Equine Vet Sci 2024;133:105008. doi: 10.1016/j.jevs.2024.105008
11. Christoffersen M, Söderlind M, Rudefalk SR, et al: Risk factors associated with uterine fluid after breeding caused by Streptococcus zooepidemicus. Theriogenology 2015;84:1283–1290. doi: 10.1016/j.theriogenology.2015.07.007
12. Rasmussen CD, Haugaard MM, Petersen MR, et al: Streptococcus equi subsp. zooepidemicus isolates from equine infectious endometritis belong to a distinct genetic group. Vet Res 2013;44:1-8. doi: 10.1186/1297–9716-44-26
13. Petersen MR, Skive B, Christoffersen M, et al: Activation of persistent Streptococcus equi subspecies zooepidemicus in mares with subclinical endometritis. Vet Microbiol 2015;179:119–125. doi: 10.1016/j.vetmic.2015.06.006
14. Skive B, Rohde M, Molinari G, et al: Streptococcus equi subsp. zooepidemicus invades and survives in epithelial cells. Front Cell Infect Microbiol 2017;7:465. doi: 10.3389/fcimb.2017.00465
15. Petersen MR, Møller Nielsen J, Lehn-Jensen H, et al: Streptococcus equi subspecies zooepidemicus resides deep in the chronically infected endometrium of mares. Clinical Theriogenology 2009;1:393–409
16. Khan Y, El-Shalofy A, Kaps M, et al: In mares resistant to endometrial infection, periovulatory treatment with ecbolic drugs does not influence uterine clearance or luteal development. Anim Reprod Sci 2024;267:107548. doi: 10.1016/j.anireprosci.2024.107548
17. Beyer T, Rink BE, Scarlet D, et al: Early luteal phase progestin concentration influences endometrial function in pregnant mares. Theriogenology 2019;125:236–241. doi: 10.1016/j.theriogenology.2018.11.018
18. Freccero F, Mislei B, Bucci D, et al: Effects of intra-uterine fluid accumulation after artificial insemination on luteal function in mares. Animals 2022;13:67. doi: 10.3390/ani13010067
19. Scott CJ, de Mestre AM, Verheyen KL, et al: Bayesian accuracy estimates and fit for purpose thresholds of cytology and culture of endometrial swab samples for detecting endometritis in mares. Prev Vet Med 2022;209:105783. doi: 10.1016/j.prevetmed.2022.105783
20. Riddle WT, LeBlanc MM, Stromberg AJ: Relationships between uterine culture, cytology and pregnancy rates in a Thoroughbred practice. Theriogenology 2007;68:395–402. doi: 10.1016/j.theriogenology.2007.05.050
21. Card C: Post-breeding inflammation and endometrial cytology in mares. Theriogenology 2005;64:580–588. doi: 10.1016/j.theriogenology.2005.05.041
22. Rink BE, Beyer T, French HM, et al: The fate of autologous endometrial mesenchymal stromal cells after application in the healthy equine uterus. Stem Cells Dev 2018;27:1046–1052. doi: 10.1089/scd.2018.0056
23. Nielsen JM, Nielsen FH, Petersen MR, et al: Diagnosis of equine endometritis–Microbiology, cytology and histology of endometrial biopsies and the correlation to fertility. Pferdeheilkunde 2012;28:8–13.
24. LeBlanc MM: Advances in the diagnosis and treatment of chronic infectious and post-mating-induced endometritis in the mare. Reprod Dom Anim 2010;45:21–27. doi: 10.1111/j.1439-0531.2010.01634.x
25. Christoffersen M, Brandis L, Samuelsson J, et al: Diagnostic double-guarded low-volume uterine lavage in mares. Theriogenology 2015;83:222–227. doi: 10.1016/j.theriogenology.2014.09.008
26. Von Dollen K, Lu K, Lyle S, et al: Clinical observations of bacterial culture results after intrauterine infusion of misoprostol. Clinical Theriogenology 2022;14:301.
27. Nielsen JM: Endometritis in the mare: a diagnostic study comparing cultures from swab and biopsy. Theriogenology 2005;64:510–518. doi: 10.1016/j.theriogenology.2005.01.008
28. Aurich C, Budik S: Season does not influence embryo recovery rate and conceptus size until day 14 after ovulation in the horse. Reprod Dom Anim 2015;50:299–303. doi: 10.1111/rda.12490
29. Vanderwall DK, Squires EL, Brinsko SP, et al: Diagnosis and management of abnormal embryonic development characterized by formation of an embryonic vesicle without an embryo in mares. J Am Vet Med Assoc 2000;217:58–63. doi: 10.2460/javma.2000.217.58
30. McCue PM: Ultrasound examination of the pregnant reproductive tract. In: Descanio J, McCue P: editors. Equine Reproductive Procedures. 2nd edition, Amess; Wiley Blackwell: 2021. p. 257–261.
31. Ferris R: Biofilm and latent bacteria in equine uterus. Clinical Theriogenology 2022;14:229-232. doi: 10.58292/ct.v14.9680
Published
2025-05-22
How to Cite
Khan , Y., El-Shalofy , A., Gautier , C., & Aurich , C. (2025). Early pregnancy loss in a mare due to possible acute uterine bacterial infection. Clinical Theriogenology, 17. https://doi.org/10.58292/CT.v17.12157
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Section
Case Reports
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