Canine Cryptorchidism Study Guide

Overview and Clinical Importance

Cryptorchidism is one of the most common congenital defects of the reproductive system in dogs, occurring when one (unilateral) or both (bilateral) testicles fail to descend into the scrotum. The condition is reported in 1-15% of dogs, with higher incidence in certain breeds. Understanding cryptorchidism is essential for the NAVLE because it encompasses embryology, endocrinology, oncology, and surgical principles.

The clinical significance of cryptorchidism extends beyond reproductive concerns. Retained testicles carry a 9.2 to 13.6 times higher risk of developing testicular neoplasia compared to normally descended testicles. Additionally, cryptorchid dogs face risks of testicular torsion, a painful surgical emergency. Because cryptorchidism is a heritable condition, affected dogs should never be used for breeding.

Embryology and Pathophysiology of Testicular Descent

Normal testicular descent in dogs occurs in two distinct phases, each regulated by different hormonal mechanisms. Understanding these phases is critical for comprehending why cryptorchidism occurs and how it is classified.