# Computed Tomography Assessment of Retained Testes in Dogs

## TL;DR

This study shows that CT scans can better detect and visualize undescended testicles in dogs compared to ultrasound, despite requiring anesthesia and radiation.

## Contribution

The study demonstrates CT as a valuable second-line imaging method for diagnosing retained testes in dogs when ultrasound is inconclusive.

## Key findings

- Undescended testes were about 70% smaller than normal scrotal testes.
- Undescended testes showed higher density in CT scans, possibly due to reduced sperm production or structural changes.
- CT provided clearer 3D visualization than ultrasound, especially in complex cases.

## Abstract

Cryptorchidism is a condition in which one or both testicles fail to move into their normal position in the scrotum, which can affect dogs on one or both sides. This study analyzed computed tomography scans of 19 dogs with cryptorchidism. The results showed that undescended testicles were smaller than normal ones, measuring about 70% of their size, and they had higher density, possibly due to reduced sperm production or structural changes. CT provided clearer, more detailed images than ultrasound, making it a useful tool when ultrasound is inconclusive, especially in complex cases. However, CT requires anesthesia and exposes dogs to radiation, which are important considerations. Despite these drawbacks, the findings suggest that CT can be a valuable second-line imaging method to improve diagnosis and treatment planning for affected dogs. This could help veterinarians make better decisions, ensuring timely and appropriate care while minimizing complications related to undiagnosed retained testicles.

Cryptorchidism consists in the failure of one or both testicles to fully descend into the scrotum. The position of the retained testes can be abdominal or inguinal and may occur unilaterally or bilaterally. This retrospective, multi-center study aimed to describe the computed tomography (CT) features of retained testes in dogs. Nineteen CT scans of dogs, with either unilateral or bilateral cryptorchidism, were analyzed with both pre- and post-contrast imaging. The location, size, shape, margins, homogeneous parenchyma, and density calculated were examined with the Hounsfield unit. Statistical analyses were performed to assess the differences between the scrotal (ST) and undescended testes (UT) and to detect any correlation between the features, ages, and size of the dog. CT identified the retained testes and provided enhanced three-dimensional visualization compared to traditional ultrasound. This study revealed that the UT were significantly smaller than ST, with UT measuring around 70% of ST size. Additionally, the UT exhibited increased density in both pre- and post-contrast scans, potentially due to the reduced or absent spermatogenesis or to histological changes occurring in the parenchyma. While CT showed clear advantages, such as three-dimensional spatial resolution and deeper tissue penetration, limitations such as general anesthesia and radiation exposure should also be considered. However, the present study showed that CT could serve as a valuable second step tool in cases where ultrasound fails, particularly in challenging anatomical situations.