An animal with vestiges of reproductive organs of both sexes is known as an intersexes or pseudo hermaphrodites. Causes of this abnormality spectrum vary from mutations in individual genes to chromosome abnormalities.
Freemartins: Over 90% of heifers born co-twin to a bull calf are sterile. The heifer suffers an abnormal development of the reproductive tract due to an exchange of cells and hormones between the developing fetuses, however, anatomical and reproductive features do not appear until puberty. These heifers are known as freemartins. The male co-twins are fertile but may experience lower sperm counts later in life. Freemartins also occur in other ruminant species such as sheep and goats. Definitive diagnosis is performed either by Karyotyping or PCR analysis.
Sex reversal: This condition occurs when the genetic sex (females XX chromosomes; males XY chromosomes) and anatomical sex (reproductive tracts) are different. In these cases, animals with female external genitalia have a male (XY) karyotype. Genetic sex can be diagnosed by Karyotype analysis
Androgen insensitivity: Mutations in the androgen receptor gene in males results in a failure of the normal development of the male reproductive tract in the fetus. Instead, female external genitalia, vagina and cervix develop. These animals appear as normal females except they do not have ovaries or exhibit estrous. The mutation is inherited. The Karyotekk laboratory has discovered a number of cases of this abnormality in horses and has developed a testing procedure to identify the carriers.