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Early pregnancy loss in brood mares.
Abstract: During 1985, linear-array ultrasonography was used to study early pregnancy loss in commercial brood mares: 600/1115 (54%) of the cycles resulted in detected pregnancy at Week 2 after ovulation and 80 (13%) of these pregnancies resulted in early pregnancy loss. The pregnancy loss rate was significantly higher (P less than 0.05) for twin pregnancies (10/41) than for singleton pregnancies (70/559). The pregnancy loss rate was significantly higher (P less than 0.05) at 2-4 weeks (29/60) than at 6-8 weeks (12/60). The pregnancy rate was significantly less (P less than 0.05) for post-partum mares inseminated at the foal heat (157/302) than for those inseminated at a subsequent oestrus (203/334). Mares with a history of endometritis had a significantly higher (P less than 0.05) per cycle pregnancy loss rate (7/26) than did mares with a history of not having endometritis (64/498). When mares that had lost pregnancies were re-mated, 37/75 (49%) detectable pregnancies resulted and 7 (19%) of these pregnancies were again lost. The per cycle pregnancy rate was 56% (153/273), 55% (177/319), 60% (130/216), 51% (72/142), 45% (34/76) and 33% (12/36) for mares aged 2-5, 6-9, 10-13, 14-17, 18-21 and greater than 21 years, respectively. The corresponding per cycle pregnancy loss rates were 12%, 14%, 9%, 14%, 24% and 33%.
Publication Date: 1987-01-01 PubMed ID: 3479600 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
- Research Support
- Non-U.S. Gov't
Summary
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This research article looks into the early pregnancy loss in brood mares, examining factors like twin pregnancy, the insemination period, previous history of endometritis, and age. Through ultrasonography, the study determines that the rates of early pregnancy loss are higher for twin pregnancies, for mares inseminated just after giving birth, for those suffering from endometritis, and those that are aged 18 and above.
Methodology
- The study was conducted during 1985 using linear-array ultrasonography as the main tool to understand and track the cycle of pregnancies in commercial brood mares.
- A total of 1115 cycles were observed and analyzed. The pregnancy and early pregnancy loss rates were recorded for each cycle.
Findings
- Out of the total observed cycles, 600 (54%) resulted in detected pregnancies at Week 2 post ovulation. However, 13% of these pregnancies resulted in an early pregnancy loss.
- Twin pregnancies showed a higher rate of pregnancy loss (10/41) than singleton pregnancies (70/559), with the difference being statistically significant.
- The study also found a significant difference in pregnancy loss rates based on the time of the cycle with losses at 2-4 weeks (29/60) higher than at 6-8 weeks (12/60).
Impact of Insemination Period and Endometritis History
- Post-partum mares which were inseminated at the foal heat showed a significantly lower pregnancy rate than those inseminated at a subsequent oestrus.
- The research also pointed out that the history of endometritis affects the cycle pregnancy loss rate, recording a significantly higher rate for mares with endometritis history (7/26), compared to those without (64/498).
Remating Post Pregnancy Loss and Age Factor
- Of the mares that had lost pregnancies and were re-mated, 49% resulted in detectable pregnancies. However, 19% of these pregnancies were lost again indicating the recurrence of early pregnancy loss in these mares.
- The study also considered the age of the mares as a variable, recording varying per cycle pregnancy rates and pregnancy loss rates for different age groups. Older mares (18 years and above) showed a lower pregnancy rate and higher pregnancy loss rates.
Cite This Article
APA
Woods GL, Baker CB, Baldwin JL, Ball BA, Bilinski J, Cooper WL, Ley WB, Mank EC, Erb HN.
(1987).
Early pregnancy loss in brood mares.
J Reprod Fertil Suppl, 35, 455-459.
Publication
Researcher Affiliations
- Department of Clinical Sciences, New York State College of Veterinary Medicine, Cornell University, Ithaca 14853.
MeSH Terms
- Animals
- Breeding
- Endometritis / veterinary
- Female
- Fetal Death / veterinary
- Horse Diseases / etiology
- Horses
- Pregnancy
- Twins
Citations
This article has been cited 7 times.- Antczak DF, Allen WRT. Placentation in Equids. Adv Anat Embryol Cell Biol 2021;234:91-128.
- Falomo ME, Del Re B, Rossi M, Giaretta E, Da Dalt L, Gabai G. Relationship between postpartum uterine involution and biomarkers of inflammation and oxidative stress in clinically healthy mares (Equus caballus). Heliyon 2020 Apr;6(4):e03691.
- Meyers PJ, Bonnett BN, McKee SL. Quantifying the occurrence of early embryonic mortality on three equine breeding farms. Can Vet J 1991 Nov;32(11):665-72.
- Giammarino A, Robbe D, Dainese E, Minoia R, Sciorsci RL. Mare embryonic resorption and homocysteine. Vet Res Commun 2003 Sep;27 Suppl 1:607-9.
- Huhtinen M, Reilas T, Katila T. Recovery rate and quality of embryos from mares inseminated at the first post-partum oestrus. Acta Vet Scand 1996;37(3):343-50.
- Darenius K. Early foetal death in the mare. Histological, bacteriological and cytological findings in the endometrium. Acta Vet Scand 1992;33(2):147-60.
- Scholtz M, Guthrie AJ, Newton R, Schulman ML. Review of Pseudomonas aeruginosa and Klebsiella pneumoniae as venereal pathogens in horses. Equine Vet J 2025 May;57(3):587-597.
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