# Computed Tomographic and Ultrasonographic Features in Three Dogs with Infected Uterus Masculinus and Concurrent Genital Neoplasia

## TL;DR

This paper describes three rare cases in male dogs where they developed infected female reproductive organs, using imaging techniques to better understand and diagnose this condition.

## Contribution

The first case series describing combined ultrasonographic and tomographic features of infected uterus masculinus in dogs.

## Key findings

- Imaging revealed a fluid-filled, bicornuate structure connected to the prostate in all three dogs.
- Two dogs had tumors associated with the infected uterus masculinus, including Leydig cell and granulosa cell tumors.
- Novel imaging features like cervix-like narrowing and fluid–fluid levels were observed.

## Abstract

Uterus masculinus is a rare disorder in which male dogs develop female reproductive organs. We describe three cases of infected uterus masculinus, all presenting with abdominal swelling, pain, and signs of infection. Abdominal ultrasonography and computed tomography revealed a fluid-filled, bicornuate abdominal structure connected to the prostate in all cases. In two dogs, each horn extended into the scrotum next to the testes, while in the third, both horns were entirely inside the abdomen, one of them attached to a large mass. Surgery and laboratory analyses confirmed an infected uterus masculinus, with the bacterium Escherichia coli detected in the urine of all dogs, along with diverse genital tumors. Although rare, this condition should be considered in male dogs showing abdominal swelling, pain, or infection. The imaging descriptions provided here may help veterinarians recognize this uncommon, so far poorly described disorder and treat affected dogs more effectively.

Uterus masculinus is a rare disorder of sexual development in males, characterized by the presence of tubular female genitalia. Diagnostic imaging reports of infected uterus masculinus are limited. We describe the ultrasonographic and computed tomographic findings in three dogs, all presenting with abdominal distension, pain, and systemic infection. Imaging consistently revealed a fluid-filled, bicornuate structure arising from the prostate. In two dogs, the horns extended through the inguinal rings to the scrotal testes; in the third, with a prior left orchiectomy, both horns were intra-abdominal, the right ending in a peritoneal mass. Surgery and histopathology confirmed infected uterus masculinus, with Escherichia coli isolated from urine in all dogs and from the structure in two. Two dogs had Leydig cell tumors, one with concurrent uterine neoplasia; the third had an ovarian or ovotesticular granulosa cell tumor. Although rare, infected uterus masculinus is potentially life-threatening and should be considered in male dogs with abdominal pain, distension, or systemic infection. This is the first case series describing combined ultrasonographic and tomographic features of infected uterus masculinus, including novel findings such as cervix-like mural narrowing and fluid–fluid levels. It is also the first imaging description of an ovarian or ovotesticular tumor in a dog with uterus masculinus.