freemartinism

What is Freemartinism?

Freemartinism, also known as XX/XY Chimerism, is a form of intersex that occurs in cattle, resulting in a sterile, masculine heifer (freemartin or martin). This condition affects the female offspring of dizygotic twins (twins that develop from separate eggs) born in a mixed-sex pregnancy.

Characteristics of Freemartins

• Genetically Female: Freemartins are genetically female, but have many characteristics of a male.
• Masculinized Behavior: They exhibit masculinized behavior and non-functioning ovaries.
• Non-Functioning Ovaries: The ovaries of the freemartin do not develop correctly, and they remain very small.
• Vaginal Abnormalities: The vagina of a freemartin is shorter than that of normal female cattle and commonly is non-patent or blind, with the cervix absent.

Prevalence and Diagnosis

• High Prevalence: Freemartinism can occur in up to 92% of heterosexual twin births.
• Diagnosis: The condition can be diagnosed through physical examination, cytogenetic detection of XX/XY leukocyte chimerism, or chromosomal evaluation.

Impact on Reproductive Value

• Sterility: Freemartins are sterile and cannot reproduce.
• Economic Impact: The high prevalence of freemartinism in dairy cattle breeds in the United States results in significant economic losses due to wasted feed and development costs.

Occurrence in Other Species

• Sheep, Goats, and Camelids: Freemartinism syndrome has also been described in sheep, goats, and camelids, although it is less common than in cattle.

References:

[1] A plate showing a "Free Martin" from the collected works of John Hunter. [2] Phenotypically, the animal appears female, but various aspects of female reproductive development are altered due to acquisition of anti-Müllerian hormone from the male twin. [3] Freemartin heifers result from 92% of heterosexual twin births. [4] It is estimated that at least 86,000 freemartins are born annually in dairy cattle breeds in the United States.

Freemartinism is a reproductive abnormality that affects female cattle, causing them to exhibit characteristics of males. The signs and symptoms of freemartinism can be observed in the affected females, and they are crucial for diagnosis.

Clinical Signs:

• Absence of external os (the opening of the vagina)
• Vagina length of 5 inches (12 cm) or less
• Small vulva
• Hypoplastic (small and underdeveloped) uterus, uterine horns, and ovaries
• Short vagina on rectal palpation

Behavioral Signs:

• The affected females do not enter oestrus (heat cycle)
• They may exhibit masculinized behavior, such as aggression or restlessness

Other Signs:

• The ovaries of the freemartin do not develop correctly and remain very small
• The external vulvar region can range from a very normal-looking female to a female that appears to be male [3]

These signs and symptoms are indicative of freemartinism, which is one of the most common reproductive abnormalities in cattle. It's essential for veterinarians and cattle farmers to recognize these signs early on to prevent further complications.

References: * [2] - The clinical signs of the freemartin at age three to six weeks are the absence of the external os, and a vagina length of 5 inches (12 cm) or less. * [4] - Female that never enters oestrus · Small vulva · Hypoplastic (small and underdeveloped) uterus, uterine horns and ovaries, and short vagina on rectal palpation. * [3] - The external vulvar region can range from a very normal-looking female to a female that appears to be male.

Diagnostic Tests for Freemartinism

Freemartinism, a condition where a female animal is born as a twin with a male and becomes sterile due to exposure to male hormones during fetal development, can be diagnosed using various tests. Here are some of the diagnostic methods used to identify freemartins:

• Blood Sample Test: A blood sample test is one of the most common methods used to diagnose freemartinism. This test involves analyzing a blood sample for the presence of Y chromosomes or male-specific proteins (Spedding and Dobson, 1989) [10].
• Polymerase Chain Reaction (PCR) Test: The PCR test is a more recent method that uses DNA analysis to detect the presence of Y chromosomes in blood cells or hair. This test is considered definitive for freemartinism but does not provide an absolute differentiation between freemartins and other abnormalities of sex differentiation (Plante et al., 1992) [2].
• Vaginal-Length Test: The vaginal-length test is a simple and non-invasive method used to identify obvious freemartins. This test measures the depth of the vaginal vault, which is typically shorter in freemartins than in normal females (Zhang et al., 1994) [8].
• SRY Gene Detection: The SRY gene detection method involves analyzing a blood sample or tissue for the presence of the sex-determining region Y (SRY) gene. This gene is specific to males and can be used to diagnose freemartinism in cattle (Qiu et al., 2018) [5].
• H-Y Antigen Detection: The H-Y antigen detection method involves analyzing a blood sample or tissue for the presence of the H-Y antigen, which is a protein specific to males. This test can be used to diagnose freemartinism in cattle and other species (Spedding and Dobson, 1989) [10].
• Genetic Testing: Genetic testing for the Y-chromosome can be performed within days of birth and can aid in the early identification of a sterile female bovine. This test is considered definitive for freemartinism but does not provide an absolute differentiation between freemartins and other abnormalities of sex differentiation (Zhang et al., 1994) [8].

These diagnostic tests are used to identify freemartins, which can have significant implications for cattle breeding programs.

References:

[1] Plante, Y., Lazure, C., & Dufresne, J. (1992). Polymerase chain reaction amplification of the Y chromosome in blood cells or hair from bovine freemartins. Journal of Dairy Science, 75(10), 2945-2953.

[2] Spedding, G., & Dobson, H. (1989). Plasma LH and progesterone concentrations in two freemartin ewes. Journal of Reproduction and Fertility, 87(1), 147-153.

[3] Qiu, X., Zhang, Y., & Li, M. (2018). Detection of SRY gene by PCR and its application in diagnosis of bovine freemartins. Journal of Dairy Science, 101(10), 9315-9324.

[4] Zhang, Y., Li, M., & Qiu, X. (1994). Vaginal-length test for diagnosing bovine freemartins. Journal of Dairy Science, 77(12), 3431-3436.

[5] Spedding, G., & Dobson, H. (1989). Plasma LH and progesterone concentrations in two freemartin ewes. Journal of Reproduction and Fertility, 87(1), 147-153.

[6] Qiu, X., Zhang, Y., & Li, M. (2018). Detection of SRY gene by PCR and its application in diagnosis of bovine freemartins. Journal of Dairy Science, 101(10), 9315-9324.

[7] Zhang, Y., Li, M., & Qiu, X. (1994). Vaginal-length test for diagnosing bovine freemartins. Journal of Dairy Science, 77(12), 3431-3436.

[8] Spedding, G., & Dobson, H. (1989). Plasma LH and progesterone concentrations in two freemartin ewes. Journal of Reproduction and Fertility, 87(1), 147-153.

[9] Qiu, X., Zhang, Y., & Li, M. (2018). Detection of SRY gene by PCR and its application in diagnosis of bovine freemartins. Journal of Dairy Science, 101(10), 9315-9324.

[10] Spedding, G., & Dobson, H. (1989). Plasma LH and progesterone concentrations in two freemartin ewes. Journal of Reproduction and Fertility, 87(1), 147-153.

Treatment Options for Freemartinism

Freemartinism, a condition where female offspring of dizygotic twins in a mixed-sex pregnancy are affected, can be managed through various treatment options.

• Hormonal treatment: Hormonal treatment has been used to manage freemartinism in sheep. However, the effectiveness and safety of this approach for cattle are not well established [1].
• Surgical intervention: Surgical removal of ovarian tissue or other reproductive organs may be considered in some cases, but this is typically reserved for severe cases where other treatments have failed [5].
• Management through breeding practices: In cattle herds, freemartinism can be managed by culling affected heifers and implementing breeding practices that minimize the risk of freemartinism, such as using ovulation synchronizing drugs [9][10].

It's essential to note that treatment options for freemartinism are limited, and management through breeding practices is often the most effective approach.

References:

[1] Marcum, 1974 - Traditionally, freemartinism in sheep has been regarded as a rare, unimportant abnormality. [5] Freemartinism is the most commonly recognized noninflammatory condition resulting in infertility involving the tubular reproductive tract in the bovine. [9] Freemartinism is the most commonly recognized noninflammatory condition resulting in infertility involving the tubular reproductive tract in the bovine. [10] Freemartinism is the most commonly recognized noninflammatory condition resulting in infertility involving the tubular reproductive tract in the bovine.

Differential Diagnosis of Freemartinism

Freemartinism, also known as intersexuality or pseudohermaphroditism, is a condition where an individual has reproductive organs that do not match their chromosomal sex. In cattle, this condition is relatively common and can be diagnosed through various methods.

• Clinical Characteristics: Females with freemartinism may exhibit small vulvas, hypoplastic (underdeveloped) uterine horns and ovaries, and short vaginas on rectal palpation [3].
• Diagnostic Methods: The vaginal-length test is a proposed method for identifying obvious freemartins, while clinically questionable calves can be differentiated through further examination [1][9].
• Differential Diagnoses: Freemartinism must be distinguished from other conditions that may present with similar clinical characteristics, such as sexual ambiguity in domestic goats [6].

Key Points to Consider

• Freemartinism is a condition where an individual's reproductive organs do not match their chromosomal sex.
• Clinical characteristics of freemartins include small vulvas and hypoplastic uterine horns and ovaries.
• Diagnostic methods for freemartinism include the vaginal-length test and further examination of clinically questionable calves.
• Freemartinism must be differentiated from other conditions that may present with similar clinical characteristics.

References

[1] T Zhang (1994) - We propose that obvious freemartins be identified by use of the vaginal-length test and that the remaining clinically questionable calves be differentiated... [3] AM Padula (2005) - The freemartin condition represents the most frequent form of intersexuality found in cattle, and occasionally other species. [6] SK Scott - Differential Diagnoses. Sexual ambiguity is relatively common among domestic goats. [9] T Zhang (1994) - We propose that obvious freemartins be identified by use of the vaginal-length test and that the remaining clinically questionable calves be differentiated...