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

Abstract

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.

Keywords: disorder of sexual development; karyotype; pygmy goat; whole genome sequencing.

Figure 1

Phenotypical appearance of DSD goat. (a) Phenotypical differences between female pygmy goat (left) and DSD goat (right). Larger horns, beard, and hairier head are characteristics of the DSD goat; (b) Vulva with prominent clitoris. (c) Male-like phenotypic characteristics of the DSD goat.

Figure 2

Histological section of gonad and tubular genitalia from a pygmy goat with a disorder of sexual development. The subgross section reveals a small testis with prominent epididymis (1), and two transverse sections of the associated tubular system show paired structures (2). Haematoxylin and eosin (H&E). Scale bar = 5 mm.

Figure 3

(a) Testicular tissue (1) displays numerous seminiferous tubules lined by vacuolated Sertoli cells. Efferent ductules within the epididymis (2) are devoid of spermatozoa. H&E. Scale bar = 1 mm. (b). Paired (unilateral) tubular genitalia. A well-vascularised glandular endometrium is present surrounding the larger-calibre tubular genital structure (1). A muscular ductus deferens is present (2). H&E. Scale bar = 1 mm.