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Home / Equine Research Bank / Equine Vet J / Warmblood fragile foal syndrome: Pregnancy loss in Warmblood...
Equine veterinary journal2024; 57(4); 915-923; doi: 10.1111/evj.14435

Warmblood fragile foal syndrome: Pregnancy loss in Warmblood mares.

Abstract: Fragile foal syndrome (FFS) or warmblood FFS Type 1 (WFFS) is a recessive, autosomal, hereditary, genetic defect causing late abortions, stillbirths and non-viable foals. Whether early pregnancy losses occur is unknown. Objective: To investigate how WFFS affects pregnancies and whether early pregnancy losses occur in WFFS matings and if there is a difference in pregnancy success between matings where both parents were allele carriers and those where only mare or stallion were WFFS carriers. Methods: Retrospective cohort study. Methods: Breeding records from a Warmblood stud farm were evaluated (2016-2019) and 2682 cycles of 177 mares analysed. Matings were assigned to four study groups, depending on the WFFS carrier status of the mare and stallion: N/WFFS × N/WFFS (n = 46), N/WFFS (mares) × N/N (n = 511), N/N × N/WFFS (stallions) (n = 191) and N/N × N/N (n = 2149). Results: There were no differences in pregnancy rates between matings with only one WFFS carrier and those with non-carriers. When comparing N/WFFS × N/WFFS matings to those with only one or no WFFS-carrier, there were no increased pregnancy losses in the embryonic phase (day <42). By contrast, the N/WFFS × N/WFFS group had significantly more abortions (53.8%) than the other three study groups (7.9-9.2%; adjusted p < 0.0001). The higher losses were evenly distributed between the early (D42-150: 22.7% losses, n = 5) and late (D150-300: 29.4% losses, n = 5) foetal phase. The live foal rate per pregnancy for N/WFFS × N/WFFS matings was lowest (34.5%) and differed significantly (other groups 81%-84%; adjusted p < 0.0001); the peri- and postnatal mortality was higher (25%) compared with the other study groups (2.6%-3%). Conclusions: Low sample size in N/WWFS × N/WFFS matings, unbalanced study design, outcomes are descriptive, all mares from one stud farm. Conclusions: The mating of two WFFS carriers may lead to increased risks of pregnancy and foal loss. Unassigned: Fragile foal syndrome (FFS) oder warmblood FFS Type 1 (WFFS) ist ein rezessiver, autosomal vererbter Gendefekt, der zu spätaborten, Totgeburten und nicht lebensfähigen Fohlen führt. Ob frühe Trächtigkeitsverluste auftreten, ist nicht bekannt. Unassigned: Untersucht wurde die Auswirkung von WFFS auf die Trächtigkeit, ob bei WFFS‐Paarungen frühe Trächtigkeitsverluste auftreten und ob es einen Unterschied im Trächtigkeitserfolg zwischen Paarungen gibt, bei denen beide Eltern Allel‐Träger waren, und solchen, bei denen Stuten oder Hengst WFFS‐Träger waren. Methods: Retrospektive Kohortenstudie. Methods: Zuchtregister eines Warmblutgestüts wurden ausgewertet (2016–2019) und 2.682 Zyklen von 177 Stuten analysiert. Die Anpaarungen wurden in Abhängigkeit vom WFFS‐Trägerstatus der Stute und des Hengstes vier Studiengruppen zugeordnet: N/WFFS × N/WFFS (n = 46), N/WFFS (Stuten) × N/N (n = 511), N/N × N/WFFS (Hengste) (n = 191), N/N × N/N (n = 2.149). Unassigned: Es gab keine Unterschiede in den Trächtigkeitsraten zwischen Paarungen mit nur einem WFFS‐Träger und solchen mit Nicht‐Trägern. Beim Vergleich von N/WFFS × N/WFFS‐Paarungen mit solchen mit nur einem oder keinem WFFS‐Träger gab es keine erhöhten Trächtigkeitsverluste in der Embryonalphase (Tag <42). Im Gegensatz dazu gab es in der Gruppe N/WFFS × N/WFFS deutlich mehr Aborte (53,8%) als in den anderen drei Studiengruppen (7,9‐9,2%; korrigierter p‐Wert <0,0001). Die höheren Verluste verteilten sich gleichmäβig auf die frühe (Tag 42–150: 22,7% Verluste, n = 5) und späte (Tag 150–300: 29,4% Verluste, n = 5) fetale Phase. Die Lebendfohlenrate pro Trächtigkeit war bei N/WFFS × N/WFFS‐Paarungen am niedrigsten (34,5%) und unterschied sich signifikant (andere Gruppen 81–84%; korrigierter p‐Wert <0,0001); die peri‐ und postnatale Mortalität war höher (25%) als bei anderen Studiengruppen (2,6–3%). HAUPTEINSCHRÄNKUNGEN: Geringer Stichprobenumfang bei N/WWFS × N/WWFS‐Paarungen, unausgewogenes Studiendesign, lediglich deskriptiver Bericht, alle Stuten stammten aus einem Gestüt. Unassigned: Die Paarungen von zwei WFFS‐Trägern kann zu einem erhöhten Risiko von Trächtigkeits‐ und Fohlenverlusten führen.
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Publication Date: 2024-11-14 PubMed ID: 39539185DOI: 10.1111/evj.14435Google Scholar: Lookup
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Summary

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The article investigates how Warmblood Fragile Foal Syndrome (WFFS) impacts pregnancies, and whether early pregnancy losses occur in WWFS matings. Specifically, the study compares the pregnancy success between matings where both parents were allele carriers and those where only the mare or stallion were WFFS carriers.

Study Design and Methodology

  • The study was a retrospective cohort study.
  • The researchers reviewed breeding records from a single Warmblood stud farm for the period of 2016 to 2019.
  • A total of 2682 breeding cycles from 177 mares were analyzed.
  • The mating pairs were divided into four groups depending on the WFFS carrier status of the mare and stallion. These were N/WFFS × N/WFFS, N/WFFS (mares) × N/N, N/N × N/WFFS (stallions), and N/N × N/N.

Findings of the Study

  • There was no difference observed in pregnancy rates between matings with only one WFFS carrier and those with non-carriers.
  • Comparing N/WFFS × N/WFFS matings to those with only one or no WFFS-carrier, no increase in pregnancy losses was observed in the embryonic phase (day <42).
  • Conversely, the N/WFFS × N/WFFS group had significantly more abortions, 53.8%, compared to the other three study groups which ranged from 7.9% to 9.2%.
  • The increase in losses in the N/WFFS × N/WFFS group were evenly distributed between the early and late fetal phase.
  • The live foal rate per pregnancy was lowest (34.5%) for N/WFFS × N/WFFS matings, compared to the other groups (81%-84%).
  • The peri- and postnatal mortality was higher (25%) compared with the other study groups (2.6%-3%).

Conclusion of the Study

  • The low sample size in N/WFFS × N/WFFS matings and the unbalanced study design were acknowledged as limitations of the study.
  • The findings of the study were descriptive, and all mares originated from one stud farm.
  • Nonetheless, the study concluded that the mating of two WFFS carriers could lead to increased risks of pregnancy and foal loss.

Cite This Article

APA
Kehlbeck A, Blanco M, Venner M, Freise F, Gunreben B, Sieme H. (2024). Warmblood fragile foal syndrome: Pregnancy loss in Warmblood mares. Equine Vet J, 57(4), 915-923. https://doi.org/10.1111/evj.14435

Publication

Equine veterinary journal
ISSN: 2042-3306
NlmUniqueID: 0173320
Country: United States
Language: English
Volume: 57
Issue: 4
Pages: 915-923

Researcher Affiliations

Kehlbeck, A
  • Lewitz Stud, Neustadt-Glewe, Germany.
  • Clinic for Horses, University of Veterinary Medicine Hanover, Hanover, Germany.
Blanco, M
  • Clinic for Horses, University of Veterinary Medicine Hanover, Hanover, Germany.
Venner, Monica
  • Equine Clinic Destedt, Cremlingen, Germany.
Freise, Fritjof
  • Department for Biometry, Epidemiology and Information Processing, University of Veterinary Medicine Hanover, Hanover, Germany.
Gunreben, B
  • Laboklin, Bad Kissingen, Germany.
Sieme, Harald
  • Clinic for Horses - Unit for Reproductive Medicine, University of Veterinary Medicine Hanover, Hanover, Germany.

MeSH Terms

  • Animals
  • Horses
  • Female
  • Pregnancy
  • Horse Diseases / genetics
  • Abortion, Veterinary / genetics
  • Retrospective Studies
  • Cohort Studies

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