XY disorder of sexual development in a dog: a case study by histopathology, genotyping and karyotyping.

This study aims to report a case of sexual ambiguity in a 3-yr mongrel dog and its respective etiological approach. There was a complaint of trauma and pinpoint bleeding in a chronical exposed structure, which examination indicated to be penis-like with perineoscrotal insertion and ventral hypospadia, surrounded by skin folds that resembled vulvar labia majora or hypoplastic prepuce. No evident scrotum and testicles were noted. Abdominal ultrasonography revealed ectopic testicles and an undefined structure filled with high-cellularity content in close contact with the prostate dorsal wall. The dog underwent exploratory laparotomy, revealing structures morphologically compatible with testicles and epididymides, connected by a tubular structure macroscopically resembling uterine horns, which was subjected to histopathological analysis and genotyping. For the external genitalia, penectomy was performed, followed by lateral mucosa reinsertion of the urethra, remaining a skin extension with vulvar-lips appearance. Histopathological examination revealed testicular hypoplasia and bilateral epididymal dysplasia and confirmed that the tubular structure was indeed an excessive distended epididymal duct. Blood sample was collected for cytogenetic analysis, which revealed variations in the diploid number (2n = 78, XY) due to addition (2n = 79) or absence of acrocentric autosomal chromosomes (2n < 78). Sex genotyping confirmed a male sex (XY). In conclusion, this clinical case demonstrated a XY disorder of sexual development (male pseudohermaphroditism) due to phenotypic sex ambiguity (ambiguous external genitalia), yet with a non-function degenerated testes and hypertrophic dilation of the epididymides, suggesting a disorder of male hormonal biosynthesis.