Coexistence of Rete Ovarii Cysts and Cystic Endometrial Hyperplasia in a Guinea Pig (

Reproductive system diseases are common in guinea pigs, but cases presenting with the coexistence of ovarian cysts and cystic endometrial hyperplasia (CEH) are poorly documented. This case describes a two-year-old female with abdominal tenderness and an ultrasonographic diagnosis of bilateral ovarian cysts and CEH, structured accordingly to the CARE guidelines. An ovariohysterectomy was performed via a ventral midline approach under multimodal anaesthesia and analgesia. Histopathological examination confirmed rete ovarii cysts and cystic endometrial hyperplasia. The postoperative course was uneventful, with complete recovery achieved within 21 days. To the authors' knowledge, this is the first case report, structured accordingly to the CARE guidelines, to provide complete clinical aspects, diagnostic testing (including imaging), treatment, and final confirmation of the diagnosis of both lesions in the same patient. Abdominal ultrasonography proved to be an essential tool for the simultaneous diagnosis of ovarian and uterine abnormalities in guinea pigs. Surgical management combined with multimodal anaesthesia ensured safe outcomes and satisfactory recovery. This case report also highlights the importance and value of structuring veterinary case reports according to the CARE guidelines, thereby improving the quality, transparency, and reproducibility of clinical reporting in exotic animal medicine.