Must cryptorchidism in dogs be treated with surgery?

Cryptorchidism in dogs does require surgery. When a testicle sits in the abdomen or under the abdominal skin, the higher temperature can, if not removed promptly, gradually turn it into a tumor, and a malignant tumor can be fatal.

A unilaterally cryptorchid dog can still breed, but the condition is hereditary and harms the next generation, so to avoid passing on the bad gene, have the surgery done early.