Clinical, Histological and Genetic Characterisation of a Disorder of Sexual Development in a Pygmy Goat

A 10-month-old pygmy goat was examined at the Royal (Dick) School of Veterinary Studies at the University of Edinburgh in January 2022, having been referred with a suspected diagnosis of a disorder of sexual development (DSD). The animal displayed a predominantly female phenotype (vulva with enlarged clitoris and vagina) but some male external characteristics such as a beard, larger body size, and larger horns. It also typically exhibits male behaviours such as mounting, aggression, and flehmen response. Computed tomography (CT) detected a bicornuated tubular fluid-filled structure connected to bulbous soft tissue masses. Subsequent exploratory laparotomy and reproductive tract removal identified underdeveloped uterine horns connected to ductus deferens and gonads, which were confirmed as testicles by histological examination. No spermatogenesis was detected, and no ovarian tissue was apparent. Blood levels of testosterone showed a marked decrease post-surgery (2.10 nmol/L to <0.03 nmol/L). Whole genome sequencing suggested that the patient may have an XY male karyotype, although cytological analysis was not possible to confirm the XY karyotype.