Peer-reviewed veterinary case report
Two horses with both male and female traits - what to know
By Dunn, H O et al.·Published in The Cornell veterinarian·1981·View original on PubMed →
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Original publication title: Two equine true hermaphrodites with 64,XX/64,XY and 63,XO/64,XY chimerism.
- Species:
- horse
Plain-English summary
This study looked at two horses, a Welsh pony and a Standardbred, that were both true hermaphrodites, meaning they had both male and female reproductive tissues. The Welsh pony had a mix of female (XX) and male (XY) chromosomes, while the Standardbred had a different mix that included a missing Y chromosome. Neither horse showed typical male behaviors, and both had underdeveloped male organs along with female reproductive structures. The researchers believe that the unusual genetic makeup in these horses may have happened due to a rare event during early development. The outcome of this study highlights the complex nature of their reproductive systems but does not indicate any specific treatment or health issues related to their condition.
Abstract
The karyotypes of a Welsh pony and a Standardbred were 64,XX/64,XY and 63,XO/64,XY respectively. Both intersexes were true hermaphrodites with bilateral ovotestes. Neither intersex showed stallion-like behaviour. Each one had an underdeveloped penis, bilateral seminal vesicles and uterine tissue. It would appear that the chimerism in these equine intersexes resulted from double fertilization or fusion of blastocysts. Mosaicism in the Standardbred is a possibility, resulting from loss of a Y chromosome by anaphase lag in an early embryonic XY cell.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/7194168/