Testicular Tumor (Sertoli Cell) in Dogs

PetMD Editorial
By PetMD Editorial
Published: January 9, 2009
Testicular Tumor (Sertoli Cell) in Dogs

Sertoli Cell Tumor in Dogs

Sertoli cell tumors are a form of testicular tumor in dogs, and are linked with undescended testicles. Typically, up to 14 percent sertoli cell tumors in dogs are malignant and will metastasize to surrounding lymph nodes in the body and other organs.

Symptoms and Types

The signs and symptoms of sertoli cell tumors include:

  • Skin changes may become apparent
  • One testicle that is larger than the other, with wasting or shriveling of the other testicle
  • Feminization syndrome, a condition where a male dog takes on uncharacteristic female qualities (e.g., dog’s penis may shrivel or shrink in appearance, there may be abnormal breast development, and the dog may adopt a female position to urinate)
  • An abdominal mass may become palpable (found by touch examination) if a testicle has not descended -- suggesting that the testicle remained in the abdominal cavity


Sertoli cell tumors in dogs are usually caused by cryptorchidism, or undescended testicles. Aging male dogs are most likely to develop sertoli cell tumors.


To diagnose a sertoli cell tumor, your veterinarian will first want to rule out other potential causes for a tumor or mass. These may include:

  • Hypothyroidism
  • An interstitial cell tumor (a non-cancerous tumor in the testicle)
  • Hyperadrenocorticism (too much of the hormone cortisol, a stress hormone)
  • Seminoma (a different type of testicular cancer)

Other tests that may help with diagnosis include screening for certain types of anemia (low blood iron), low white blood cell counts, and low blood platelet counts. complete blood profile will be conducted, including a chemical blood profile, and a complete blood count.

Dogs with sertoli cell tumors will usually have abnormally high levels of certain hormones, including serum estradiol and progesterone. Typically an animal with a sertoli cell tumor will have some degree of feminization, even if it is only evident at the hormonal level.


Treatment typically involves castration or removal of the testicles. This may result in a complete reversal of symptoms, or will put a halt to any further feminization if the tumor was responsible for secreting female hormones.

Living and Management

The outcome and prognosis for most dogs is very good if the tumor is detected and treated before it has had a chance to metastasize or spread into surrounding organs. Most of the time there are few complications associated with treatment.

Some dogs may develop male feminization syndrome, meaning they will have enlarged breasts and assume other female characteristics or traits. This side effect occurs in up to 29 percent of dogs affected with sertoli cell tumors.

Dogs with testicular tumors that penetrate the abdominal cavity have up to a 70 percent chance of developing female traits. There is a small risk of developing liver failure from over production of estrogen over time when symptoms have been prolonged, and when there is lack of treatment.

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