A Case of XX Disorder of Sexual Development in a Female-Phenotype Roe Deer (Capreolus capreolus L.) Associated with Antlers Growth with Retained Velvet

Simple Summary Disorders of sexual development (DSDs) are characterized by incongruity between the genetic and phenotypic sex, which can be caused by anomalies in sex differentiation or gonad sex development, or abnormal sexual-hormone secretion and receptor-expression patterns during embryonic development. DSD cases can retain both ovarian and testicular tissues in one single gonad (ovotestis) or in two separate gonads. These disorders have already been described in different mammalian species, including domestic animal species. However, reports of sexual abnormalities in wild species are scarce. The present work reports a specimen of roe deer (Capreolus capreolus L.) with an intersex phenotype, as the animal presented antler growth in the presence of a typically female genital phenotype. A clinical, histopathological, and molecular study was subsequently performed. A 3-to-4-year-old roe deer (Capreolus capreolus L.) was admitted to the Veterinary Hospital. Although it showed well-developed antlers with retained velvet, an external female appearance and genitalia were evident. External biometrical measurements were taken for the antlers, and a computed tomography was performed. Molecular studies targeting the SRY gene were performed, and a PIS (polled intersex syndrome) mutation diagnosis was implemented. The gonads consisted of a right testicle paired with a left ovotestis. Histologically, the ovary-like structures in the ovotestis were functional, but the testis, as the testis-like structure in the ovotestis, did not show active spermatogenesis. No evidence of SRY gene was detected by PCR, suggesting an XX-chromosome constitution. Additionally, polled intersex syndrome (PIS) deletion was not detected in the case under study. The clinical and histopathological findings confirmed the DSD with the presence of a testicle and a contralateral ovotestis.