First case report of urothelial cyst in a dog: diagnostic approach.

Abstract

IMPORTANCE: Cystic masses in the abdominal cavity near the vaginal area can have a range of origins, including urothelial cysts, which have never been reported in dogs. This paper reports the first known occurrence of a urothelial cyst in a dog. CASE PRESENTATION: An 18-year-old, 2.05 kg intact female Maltese dog presented with a mammary nodule with no systemic clinical signs. The radiographs and ultrasound revealed a large cystic mass in the abdominal cavity. Computed tomography imaging showed that the mass was in contact with the bladder, urethra, and vagina but had no direct connections to these organs. Surgical removal was performed. Histopathology analysis confirmed a urothelial cyst lined with transitional and stratified squamous epithelium. CONCLUSIONS AND RELEVANCE: This case highlights the need to include urothelial cysts in a differential diagnosis of cystic masses near the vaginal region in dogs. Early imaging-based detection is crucial to preventing misdiagnoses and ensuring appropriate surgical intervention. Veterinarians must carefully differentiate this condition from other reproductive disorders, including pyometra and uterine tumors, to avoid complications and ensure appropriate management.