Bilateral Ovotestes in a 78, XX SRY-Negative Beagle Dog

This report describes a disorder of the sexual development in a beagle dog resulting in an intersex condition. A 6 mo old beagle was presented for evaluation of a protruding structure from the vulva consistent with an enlarged clitoris. Ultrasonographic examination revealed the presence of both gonadal and uterine structures. Retrograde cystourethrovaginogram showed the presence of an os clitoris and severe vaginal stenosis. Histological studies revealed the presence of bilateral ovotestes and uterus. The gonad had interstitial cells within seminiferous-like tubules lined only with Sertoli cells and abundant interstitial cells among primordial, primary, and secondary follicles. Hormone assays completed before and after gonadohysterectomy showed an elevation in the levels of progesterone and dihydrotestosterone that returned to baseline 3 mo after surgery. Testosterone levels that were within the male reference ranges before surgery decreased to basal levels postsurgically. 17-β-Estradiol levels showed little variation and values were always within the reference ranges for a male. Cytogenetic analysis showed a normal female karyotype (2n = 78, XX) and polymerase chain reaction analysis revealed the absence of the sex-determining region Y gene. In summary, the dog presented bilateral ovotestes and a 2n = 78, XX chromosomal complement lacking the sex determining region Y gene, consistent with a diagnosis of true hermaphroditism.