Cryptorchidism — failure of one or both testes to descend into the scrotum — is a common developmental condition in dogs associated with significantly elevated cancer risk and welfare consequences.
Cryptorchidism itself causes minimal welfare impact — the retained testis may cause some discomfort from its abnormal position but typically does not cause pain. The welfare concern is the elevated cancer risk over the dog's lifetime. Sertoli cell tumours from retained testes can cause paraneoplastic feminisation syndrome (bone marrow suppression, hair loss, enlarged prostate) that significantly impairs welfare. Testicular torsion — where the retained testis twists on its vascular pedicle — causes acute, severe pain requiring emergency surgery. Prophylactic castration as puppies is the welfare-positive preventive intervention that eliminates both risks permanently. The heritable nature also makes not breeding from cryptorchid males an important welfare consideration for future generations.