Canine Testicular Tumors Study Guide

Overview and Clinical Importance

Testicular tumors are among the most common neoplasms affecting the male reproductive system in dogs. They represent approximately 90% of all cancers originating from the male reproductive tract. These tumors are encountered frequently on the NAVLE due to their clinical significance, association with cryptorchidism, and potential paraneoplastic effects including hyperestrogenism and bone marrow suppression.

The three primary types of testicular tumors in dogs are Sertoli cell tumors (SCT), interstitial (Leydig) cell tumors (ICT), and seminomas. These tumors occur with roughly equal frequency in the general population, though their clinical presentation and behavior differ significantly. Approximately 27% of intact male dogs will develop testicular tumors in their lifetime, with incidence increasing substantially in dogs over 10 years of age.

Classification and Cell Origin

Testicular tumors arise from two primary cellular components: sex cord-stromal elements (Sertoli cells and Leydig/interstitial cells) and germ cells (seminomas). Understanding the embryonic origin of these cells is essential for predicting tumor behavior and clinical manifestations.