Three Cocker Spaniel dogs, 2-3 moths old weighing 3-4 kg were presented to the Animal Medical Centre, Chonbuk National University with intersex anomalies. Physical, radiological, gross, histological, hormonal and cytogenetic studies were performed. Physical examination of the external genitalia revealed dogs possessed vulva with an enlarged clitoris protruding from the vulvar juncture and the scrotum with an undescended testis in case 1 and 2, and both testes remained undescended in case 3. Hyperestrogenemia and low testosterone serum concentrations were found. Laparotomy revealed persistant Müllerian ducts (PMD) in case 1 and 2, and abdominally located testicle(s) in all the cases. Histological examination of the gonads revealed inactive seminiferous tubules. Cytogenetic analysis showed a 78XY male karyotype in case 1 and 2, whereas case 3 showed 79XX female karyotype. The congenital defects were diagnosed as male pseudohermaphroditism (MPH) and PMD in case 1 and 2, and XX sex reversal MPH in case 3.