Bovis ISSN 2398-2993

Freemartinism

Synonym(s): Freemartin

Contributor(s): Ben Dustan , Jo Oultram

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Introduction

  • Cause: fusion of blood vessels within the placenta of mixed sex twin conceptuses resulting in H-Y antigen (anti-Mullerian duct hormone) and testosterone secreted by the earlier sex differentiating male conceptus influencing the sex differentiation of the female conceptus.
  • Treatment: none.
  • Prognosis: guarded - poor for breeding (~8% female twins born to mixed sex pregnancies are sterile).

Pathogenesis

Etiology

  • Phenotypic female born co-twin to a male.
  • Sexual differentiation occurs earlier in the male embryo.
  • Anastomoses between the placental (chorionic) blood vessels of the different sex twins allows transfer of male tissue specific antigen (H-Y antigen / identical to Mullerian-inhibiting substance) to the female twin, which inhibits development of the female gonad.

Pathophysiology

  • Variable abnormalities of the genital organs, ranging in severity depending on when the fusion / anastomosis of blood vessels occurred.
    • Hypoplastic ovaries (often contain seminiferous tubules) .
    • Absence of cervix.
    • Cord-like uterine horns (occasionally near normal size).
    • Blind-ending, shortened vagina.
      • 5 - 6 cm in freemartin cf 13 - 15cm in normal female aged 1 - 4 weeks.
      • 8 - 10cm in freemartin cf 20 - 30cm in normal female adult cattle.

Timecourse

  • Short vaginal length apparent from birth.
  • Features become more pronounced as the animal ages.

Epidemiology

~82 - 90% phenotypic females born twin to a male are freemartins.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed Papers

  • Recent references from PubMed and VetMed Resource.
  • Long S E (1990) Development and diagnosis of freemartinism in cattle. In Practice (12) pp 208-210.

Other sources of information

  • Andrews, Blowey, Boyd & Eddy (2008) Bovine Medicine. 2nd Edn. pp 183-184.
  • Smith (2002) Large Animal Internal Medicine. 3rd Edn. pp 1301.
  • Jones, Hunt & King (1997) Veterinary Pathology. 6th Edn. pp 1155-1156.


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