Ovarian granulosa cell tumour in a 5‐month‐old dog: An unusual cause of vaginal hyperplasia and hyperoestrogenism

A 5‐month‐old prepubertal crossbred female dog presented with a 6‒8‐day history of progressive vaginal swelling and mucous discharge. The animal had normal appetite and general condition, with no history of pro‐oestrus bleeding and oestrus, suggesting that the dog was in a prepubertal stage. Clinical examination revealed marked vulvar enlargement and a soft hyperplastic mass arising from the dorsal vaginal wall, along with a firm mid‐abdominal mass on palpation. Ultrasonography identified a well‐defined echogenic mass measuring 11‒14 cm. Haematological, liver and kidney parameters were normal, while oestrogen levels were markedly elevated with normal progesterone. A provisional diagnosis of ovarian neoplasia was made and confirmed histopathologically as a granulosa cell tumour. Surgical management via ovariohysterectomy resulted in complete recovery. This case emphasises the importance of considering ovarian tumours in young dogs with reproductive abnormalities.