Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
2396275 | Journal of Equine Veterinary Science | 2009 | 5 Pages |
A 4-year-old Icelandic horse, considered to be a mare, showed stallion-like behavior in a group of mares. On clinical examination, the horse turned out to have an enlarged erectable phallic clitoris. Ultrasound examination showed a normal-sized left ovary covered with numerous small follicular cysts and a compact testis-like tissue in place of the right ovary. The karyotype was normal for a mare (64,XX), and the horse was found to be negative for the Y chromosome–specific markers SRY, ZFY, and EIF1AY. This case indicates that the intersexual phenotype may be caused by autosomal recessive mutation, resulting in defects in cortisol biosynthesis rather than transferal of Y chromosome male–specific genes. This is the first report of an intersexual phenotype in an Icelandic horse that is likely to be a true hermaphrodite because of female sex chromosomes and a mixture of female and male gonads and external genitals.