freemartinism

Freemartinism is a common form of pseudohermaphroditism in cattle, occurring when a female born twin to a male. The condition arises from the shared placental circulation between the male and female fetuses. During gestation, hormones from the male fetus can influence the development of the female fetus, leading to the underdevelopment of her reproductive organs.

A freemartin heifer typically exhibits external female characteristics but possesses internal reproductive organs that are underdeveloped or non-functional. This often includes a small or absent vagina, an infantile uterus, and undeveloped ovaries. While external genitalia appear normal, the internal anatomy prevents the freemartin from conceiving or carrying a pregnancy.

The incidence of freemartinism is high, estimated to be over 90% in heterosexual twin births in cattle. Diagnosis is usually made by observing the reproductive tract, often during post-mortem examination or by veterinary inspection. While freemartins can be used for meat production, they are infertile and cannot be used for breeding purposes. The condition is specific to cattle and does not typically occur in other species.