A 4-year old, primiparous, female Anatolian Shepherd dog was presented for evaluation of type II vaginal prolapse with alopecia of the left perineal skin. Hematological analyses demonstrated leukocytosis and thrombocytopenia. Estradiol (E2) and progesterone (P4) levels were 156 pg/mL and 2.3 ng/mL, respectively. The vaginal smear was predominantly (at least 80%) made up of anuclear superficial cells. An abdominal ultrasonography revealed a heterogeneous multicystic mass with anechoic areas adjacent to the caudal pole of the left kidney. An ovariohysterectomy was performed. Ten days after the surgery, the prolapsed vagina was completely regressed. A histopathological examination of the ovarian mass demonstrated that it was a granulosa cell tumor.