A cryptorchid cat has one or both testicles that failed to drop into the scrotum, remaining instead somewhere inside the body or in the groin area. About 1.12% of male cats presented for neutering are cryptorchid, making it an uncommon but far from rare condition. The retained testicle still produces testosterone, which means these cats behave like intact males, spraying, fighting, and producing that unmistakable tom-cat urine smell, even if an owner assumes the cat was neutered or is “missing” a testicle.
How Testicles Normally Descend
In kittens, the testicles form near the kidneys and gradually migrate downward through the abdomen, passing through a narrow channel called the inguinal canal, and finally settling into the scrotum. This process is usually complete by the time a kitten is a few months old. When the journey stalls partway, the testicle can end up lodged in one of two places: inside the abdomen (the more common and harder-to-find location) or within the inguinal canal in the groin.
A cat can be unilaterally cryptorchid, with one testicle retained and one in the scrotum, or bilaterally cryptorchid, with both retained. Unilateral cases are more common. In either scenario, the retained testicle is functional enough to pump out hormones but typically cannot produce viable sperm because it sits at a temperature too high for normal sperm development.
Signs You Might Notice
The most telling signs of cryptorchidism are the same behaviors you’d expect from any unneutered male cat: urine spraying, aggression toward other cats, and a strong, pungent urine odor. These behaviors persist because the retained testicle keeps producing testosterone at significant levels. A cryptorchid cat will show sexual interest, can achieve erections, and will mark territory just like a fully intact tom.
This creates a confusing situation for some owners. If a cat was adopted as a stray or from a shelter and appears to have an empty scrotum, it might be mistaken for a neutered cat. But the behavioral signs tell a different story. One case report described a four-year-old domestic longhair referred to a veterinarian specifically because of aggressive behavior and urine spraying, with the retained testicle ultimately identified as the cause.
Why It Happens
Cryptorchidism is considered a genetic condition, meaning it can be passed from parent to offspring. This is the primary reason veterinarians recommend removing both testicles in a unilaterally cryptorchid cat: the normally descended testicle works fine for reproduction, and any male kittens produced could inherit the same problem. Breeding a cryptorchid cat, or a cat known to carry the trait, is strongly discouraged.
No specific cat breeds have been statistically confirmed to carry a higher risk, though the condition appears across all breeds and mixed-breed cats alike.
Health Risks of a Retained Testicle
A testicle sitting inside the abdomen faces two serious risks over time. The first is testicular cancer. Retained testicles are significantly more prone to developing tumors than normally descended ones, likely because of the chronically elevated temperature inside the body cavity. The second risk is testicular torsion, where the retained testicle twists on its blood supply, cutting off circulation. Torsion is a painful emergency that requires immediate surgery.
Neither of these risks applies to cats that have been properly treated, which is why surgical removal is strongly recommended rather than a wait-and-see approach.
How Veterinarians Confirm the Diagnosis
In many cases, a vet can diagnose cryptorchidism through a simple physical exam. If only one testicle is felt in the scrotum, or neither is present despite the cat clearly showing intact male behaviors, cryptorchidism is the likely explanation. For inguinal retention, the vet can sometimes feel the testicle in the groin area.
When the picture is less clear, particularly if there’s no record of whether the cat was previously neutered, a blood test can settle the question. Testosterone levels in castrated cats fall below 50 picograms per milliliter, while cryptorchid cats typically show levels between 100 and 500. If further confirmation is needed, a stimulation test can be performed: a baseline blood sample is drawn, a hormone injection is given, and a second sample is taken two hours later. A meaningful rise in testosterone confirms that testicular tissue is still present somewhere in the body. Ultrasound can also help locate the retained testicle before surgery.
Surgical Treatment
Surgery is the only treatment for cryptorchidism. Both testicles are removed, even in unilateral cases, to eliminate cancer risk, prevent torsion, resolve behavioral issues, and ensure the genetic trait isn’t passed along.
The complexity of the surgery depends on where the retained testicle is located. If it’s in the inguinal canal, the procedure is relatively straightforward. If it’s deep in the abdomen, the vet needs to open the abdominal cavity to find and remove it, which makes the operation more involved than a standard neuter. In some cases, a laparoscopic (minimally invasive) approach is available. Research in dogs found that laparoscopic cryptorchid surgery had fewer anesthetic complications, shorter average surgical times (about 53 minutes versus 64 for open surgery), and significantly faster discharge rates, with 93% of laparoscopic patients going home the same day compared to 46% of those who had open abdominal surgery. While this data comes from canine studies, the same principles apply to cats, and more veterinary surgical centers are offering laparoscopic options.
Because a cryptorchid neuter requires more exploration than a routine procedure, it costs more. The exact price varies by clinic and by whether the testicle is inguinal or abdominal, but the additional surgical time and complexity translate to higher fees compared to a standard neuter.
Recovery After Surgery
Recovery from a cryptorchid neuter takes longer than from a routine one. If the vet had to search through the abdomen to locate the testicle, your cat will likely be sore for one to two weeks. Expect your cat to return to normal bowel movements within a day or two after the procedure, and plan for a follow-up visit roughly two weeks later so the vet can check the incision site.
Keeping your cat calm and restricted from jumping or rough play during those first two weeks is important, especially after abdominal surgery. An e-collar or recovery suit helps prevent licking at the incision. Complications are uncommon but can include swelling at the surgical site (seromas, which usually resolve on their own) and, rarely, accidental damage to nearby structures during the search for a deeply retained testicle.
Once the retained testicle is removed and testosterone levels drop, behavioral changes follow. Spraying, aggression, and the strong urine odor typically diminish within weeks, though deeply ingrained habits like marking may take longer to fully resolve in older cats.