Cryptorchidism

A developmental condition in male cats where one or both testicles fail to descend from the abdomen into the scrotum. Retained testicles carry a significantly elevated cancer risk and should always be surgically removed.

Guide only. Any suspected abnormality in a male cat's anatomy should be assessed by a vet. Do not attempt to examine or manipulate the area yourself.

Definition

Cryptorchidism (from the Greek for "hidden testicle") is a condition where one or both testicles remain inside the body rather than descending into the scrotum during development. In cats, the testicles typically descend before or shortly after birth. A testicle that has not descended by 6 months is considered retained.

The retained testicle may be located in the abdomen (intra-abdominal cryptorchidism) or in the inguinal canal between the abdomen and the scrotum. Unilateral cryptorchidism (one retained testicle) is more common than bilateral (both retained).

Why it matters

Retained testicles are exposed to the higher core body temperature of the abdomen rather than the cooler temperature of the scrotum, which is essential for normal spermatogenesis. This has two consequences:

Elevated cancer risk: Retained testicles are up to 10 times more likely to develop testicular cancer than normally descended testicles. The most clinically significant tumour type is the Sertoli cell tumour, which can secrete oestrogen and cause feminisation — enlarged mammary glands, attraction of other male cats, and symmetrical hair loss.
Normal testosterone production: Despite being unable to produce viable sperm, a retained testicle continues to produce testosterone, maintaining territorial behaviour, spraying, and roaming.

Diagnosis

Cryptorchidism is typically identified during physical examination — often at the initial kitten health check that should be booked within 48–72 hours of bringing a kitten home (covered in our first week home guide). The vet palpates the scrotum and inguinal region to check for the presence of both testicles.

An intra-abdominal testicle may not be palpable from the outside. Ultrasound is the preferred imaging method to locate a retained abdominal testicle before surgery.

Treatment

Surgical removal of both testicles (cryptorchidectomy) is the only appropriate treatment. This is recommended for all cryptorchid cats because:

It eliminates the cancer risk of the retained testicle
It prevents testosterone-driven behaviours (spraying, roaming, fighting)
It prevents accidental breeding if the cat is unilaterally cryptorchid with a functional scrotal testicle

Because finding and removing an intra-abdominal testicle requires exploratory surgery, cryptorchidectomy is more complex and costly than standard neutering. Most vets recommend addressing it as part of the planned neutering procedure rather than delaying.

Cryptorchidism is believed to have a heritable component, so cryptorchid cats should not be used for breeding.

Frequently asked questions

How common is cryptorchidism in cats?

Cryptorchidism affects approximately 1–2% of male cats. It is more common in pedigree breeds, particularly Persians and related breeds, suggesting a heritable component. Most affected cats are unilaterally cryptorchid — retaining one testicle — rather than bilateral (both retained).

Can a cryptorchid cat still be fertile?

Unilaterally cryptorchid cats — with one descended testicle — can be fertile because the scrotal testicle produces viable sperm. Bilaterally cryptorchid cats are sterile because sperm production requires the lower temperature of the scrotum. However, cryptorchid cats of any type can still produce testosterone, which drives territorial behaviour and spraying. Neutering is strongly recommended for all cryptorchid cats.

Why does a retained testicle increase cancer risk?

Retained testicles are up to 10 times more likely to develop testicular tumours than normally descended testicles. The most common tumour type in retained testicles is a Sertoli cell tumour, which can produce oestrogen and cause feminisation signs. Because the retained testicle is internal and not visible, owners often cannot detect problems early — which is another reason surgical removal (cryptorchidectomy) is recommended as part of neutering.

How is cryptorchidism diagnosed?

Your vet will palpate the scrotum and inguinal canal during examination. If only one testicle is present in the scrotum, the retained testicle may be detectable by palpation in the inguinal area or may require ultrasound to locate if abdominal. The diagnosis is usually made at the first kitten health check or at the time of planned neutering. See our first week home guide for what the vet checks at the initial kitten appointment.

What is the treatment?

Surgical removal (cryptorchidectomy) of both testicles — the retained one and the normally descended one. Because the retained testicle may be in the abdomen, the surgery is more complex than standard neutering and typically costs more. Both testicles must be removed to prevent testosterone-driven behaviour and eliminate the cancer risk. See our when to call the vet guide if you notice signs suggesting a retained testicle in an older unneutered cat.