Overview

Cryptorchism is a condition where one or both testicles fail to descend into the scrotum as a puppy develops. A retained testicle may remain inside the abdomen or in the groin (inguinal) region. Right-sided inguinal cryptorchidism is the most common presentation. 

Dogs with cryptorchidism have a significantly higher risk of developing testicular cancer in the undescended testicle or experiencing testicular torsion, a painful condition that requires urgent veterinary care.

The recommended treatment for cryptorchidism is neutering, which involves the surgical removal of both testicles. Neutering prevents serious complications related to cryptorchidism and ensures that future generations do not inherit the condition. 

Cause

Cryptorchidism is a heritable condition, although the exact pattern of inheritance is not fully understood. Certain breeds are more commonly affected, including German Shepherds, Siberian Huskies, Bulldogs and other brachycephalic breeds, as well as some small breeds like Chihuahuas and Yorkshire Terriers. In a normal male puppy, the testicles develop in the abdomen and descend into the scrotum through a passage called the inguinal canal, guided by a cord-like tissue called the gubernaculum. As the puppy develops, the gubernaculum shortens, pulling the testicles closer to the scrotum, usually completing this process by six to eight weeks of age. 

With cryptorchidism, one (unilateral) or both (bilateral) testicles fail to descend into the scrotum due to a deviation from normal testicular descent and remain either in the abdomen or the inguinal region. The inguinal canal closes around six months of age. If the testicles are not in the scrotum by that time, the puppy is considered cryptorchid. 

Risks

Dogs with retained testicles are significantly more likely to develop testicular cancer. Various testicular tumors can occur, each with their own clinical signs. One common tumor, Sertoli cell tumor, can produce hormones (hyperestrogenism) that cause changes such as feminization or symmetrical hair loss.

Another risk is testicular torsion, where the retained testicle twists on itself, cutting off its blood supply. Testicular torsion is a very painful, urgent condition that requires immediate veterinary attention.

Diagnosis

Your veterinarian may suspect cryptorchidism if one or both testicles are not in the scrotum by eight weeks of age. The diagnosis is confirmed at six months of age if the testicles still have not descended.

If the testicle can be felt under the skin in the groin, an inguinal cryptorchid is diagnosed. If no testicle can be felt, the testicle is likely within the abdomen. An abdominal ultrasound may be recommended to locate a retained testicle before surgery.

In dogs with no palpable testicles, or when there's uncertainty about whether a dog has been neutered, blood tests measuring hormones can confirm whether testicles are still present. 

Clinical signs

Most dogs with cryptorchidism appear completely normal aside from missing testicle(s) in the scrotum. 

Even though a retained abdominal testicle will not produce viable sperm because the core body temperature is too warm, it still produces testosterone, which means dogs can still exhibit hormonally driven behaviors, such as urine-marking or roaming. 

Clinical signs develop if there is a complication related to the retained testicle: 

• Testicular cancer signs depend on the type of cancer but may include enlargement of the retained testicle, prostate problems, or hormone-related changes, such as symmetrical hair loss and feminization.
• Testicular torsion causes sudden and severe abdominal pain. 

Treatment

The treatment for cryptorchidism is surgical removal of both testicles (neuter). The surgical approach varies depending on the location of the retained testicle. If the retained testicle is in the groin, a small incision can usually be made directly over it. If the retained testicle is in the abdomen, surgery is performed through an abdominal incision.

The retained testicle is often smaller than normal, which can sometimes make it more difficult to find. If a testicle cannot be located during surgery, follow-up hormonal blood tests may be recommended to check for the presence of testicular tissue.

Outcome

The prognosis for dogs with cryptorchidism after surgical removal of both testicles is excellent. Surgery eliminates the risk of testicular cancer and torsion. Recovery is similar to that of a routine neuter or abdominal surgery. 

Without surgery, dogs stay at a higher risk of testicular cancer or torsion. Most testicular cancers rarely spread to other parts of the body (metastasize), and surgical removal of the affected testicle usually cures the condition.

Prevention

Since cryptorchidism is a heritable condition, affected dogs should not be bred. Neutering your dog not only safeguards his health but also helps prevent passing on the trait to future generations.