# Coexistence of Rete Ovarii Cysts and Cystic Endometrial Hyperplasia in a Guinea Pig (Cavia porcellus)—A Detailed Clinical Case Report

## TL;DR

This case report describes a guinea pig with ovarian and uterine abnormalities, highlighting the use of ultrasound and proper surgical techniques for diagnosis and treatment.

## Contribution

This is the first case report following CARE guidelines to document coexisting ovarian cysts and cystic endometrial hyperplasia in a guinea pig.

## Key findings

- Ultrasound successfully diagnosed bilateral ovarian cysts and cystic endometrial hyperplasia in a guinea pig.
- Surgical removal combined with multimodal anesthesia ensured a safe and full recovery.
- The case emphasizes the importance of using the CARE guidelines for veterinary case reporting.

## Abstract

Reproductive diseases are common in domestic guinea pigs, especially in adult females. Among these disorders, ovarian cysts and uterine disease are the most frequent, although they are rarely documented in detail. This report describes a guinea pig that showed abdominal pain and was diagnosed with bilateral ovarian cysts and cystic hyperplasic change in the uterine wall. Ultrasound examination made it possible to identify both problems before surgery, allowing appropriate planning of the treatment. A surgical procedure was performed to remove the ovaries and uterus, using a safe anaesthetic protocol and a technique specifically adapted to this species. The recovery was fast and complete within three weeks. This case highlights the value of ultrasound as a diagnostic tool in small exotic animals and underlines the importance of clearly and systematically documenting clinical and surgical procedures. Doing so contributes to improving veterinary care and welfare in exotic companion species.

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.