Cryptorchidism (Retained Testicle)

Cryptorchidism simply means that a testicle has not made it to where it belongs. In a normally developing male kitten, the testicles form inside the abdomen and then migrate down through the groin into the scrotum, a journey that should be finished within the first weeks to a couple of months of life. When one — or occasionally both — gets stuck along the way, it stays lodged in the abdomen or somewhere in the inguinal region, and the scrotum feels empty on that side. It is one of the more common developmental quirks seen in young male cats.

A retained testicle is usually painless and the cat is otherwise healthy, so the condition is often noticed either during a routine kitten check or, revealingly, when a cat that was supposedly neutered keeps behaving like an intact tom. Because a retained testicle still produces hormones, these cats can continue to spray pungent urine, roam, and show tom-cat aggression, and they remain fertile if the descended side was left. That mismatch between an apparent neuter and persistent male behaviour is a classic clue.

The reason vets recommend removing retained testicles rather than ignoring them is risk. A testicle kept at body temperature inside the abdomen is significantly more prone to developing tumours later in life, and it is also vulnerable to torsion, a painful twisting that becomes an emergency. Surgery resolves both concerns and stops the unwanted behaviours. Since the trait is inherited, affected cats and their parents should be kept out of any breeding programme.