Infertility in the horse associated with chromosomal abnormalities

Area of Science:

• Veterinary Genetics
• Reproductive Biology
• Equine Science

Background:

• Reproductive failure is a significant concern in equine breeding.
• Chromosomal abnormalities can lead to infertility in various species.
• Understanding the genetic basis of reproductive failure in mares is crucial for breeding programs.

Purpose of the Study:

• To investigate the karyotypes of mares experiencing reproductive failure.
• To correlate specific chromosomal abnormalities with ovarian pathology in affected mares.

Main Methods:

• Peripheral blood lymphocytes were isolated using density gradient procedures.
• Karyotyping was performed using standard lymphocyte culture methods.
• Ovaries from affected mares were surgically removed and histologically examined for germ cells and stromal development.

Main Results:

• Nine out of twelve mares exhibited a 63,XO karyotype, consistent with equine Turner syndrome.
• Mosaic karyotypes (63,XO/64,XX and 63,XO/64,XY) were identified in two mares.
• One mare had a normal female karyotype (64,XX).
• Ovaries were small and firm, lacking germ cells and composed of undifferentiated ovarian stroma in examined cases.

Conclusions:

• The 63,XO karyotype (equine Turner syndrome) is strongly associated with reproductive failure in mares.
• The absence of germ cells and ovarian dysgenesis are key pathological findings in these mares.
• Karyotyping is an essential diagnostic tool for identifying the cause of reproductive failure in infertile mares.