XX vs XY: Disorders of Sexual Development in a Pig
A 6-week-old presumed female Yorkshire/Landrace pig with a left inguinal hernia presented for use in a surgical exercises lab. A uterus and ovaries were not found on exploratory laparotomy, but ductus deferens and persistent cranial suspensory ligaments were identified exiting the deep inguinal rings. Additionally, a phallus-like structure was easily everted from the presumed vulva during necropsy. Despite these findings indicating masculinization, histopathology failed to identify gonadal tissue, and testosterone levels were undetectable. However, the pig was genetically male, as PCR demonstrated that the pig was positive for SRY, the Y-linked testis-determining factor, yet the sequence amplified was abnormally short. We hypothesize this pig had gonadal regression due to a defective SRY protein, resulting in a regression of male gonads and secondary sexual characteristics. This is a report of a rare, SRY positive disorder of sexual development in a pig, likely due to spontaneous genetic mutation. Abbreviations SRY: sex-determining region Y. WNT4: Wingless-related integration site 4. SOX9: SRY-Box 9. RSPO1: R-spondin 1.