Sertoli Cell Tumor in Dogs

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Overview of Sertoli Cell Tumor in Dogs

A Sertoli cell tumor is a tumor in the testicles that involves the specific cells called Sertoli cells that can occur in dogs. Sertoli cell tumors are usually slow growing and noninvasive, although 10 to 20 percent may be malignant.

The specific cause of tumor development is unknown, but dogs that are cryptorchid, which means they have a testicle that has not descended into the scrotum, are 10 times more likely to develop a tumor. Cryptorchid testicles are generally intra-abdominal (within the abdomen), but may be under the skin in the inguinal area, or the area of the body where the hind leg meets the body wall.

Breeds at greater risk of cryptorchidism like Weimaraners and Shetland sheepdogs are more likely to develop a Sertoli cell tumor. Boxers are at increased risk of all testicular tumors regardless of cryptorchidism. Dogs are more likely to develop a Sertoli cell tumor with age.

Sertoli cell tumors are the most common tumors that cause a male feminizing syndrome due to changes in sex hormone production. About 25 percent of dogs with this tumor develop the male feminizing syndrome. Sertoli cell tumors can also cause a severe bone marrow disorder (bone marrow hypoplasia).

Most dogs that present with Sertoli cell tumors are not ill, and many are simply found during a routine physical examination.

What to Watch For

Signs of Sertoli Cell Tumor in Dogs may include: 

  • Soft or firm swellings in one or both testicles
  • A single enlarged testicle or asymmetric testicles
  • Generalized scrotal enlargement
  • Infertility in the breeding stud dog

    If male feminization is present:

  • Enlargement of the mammary glands
  • A symmetrical hair loss
  • Hyperpigmentation, which causes the skin to darken or turn black
  • Decreased libido and a pendulous prepuce
  • Diagnosis of Sertoli Cell Tumor in Dogs

  • A good physical examination including palpation (feeling) of the testicles
  • Complete blood count (CBC)
  • Platelet count
  • Biochemical profile
  • Urinalysis with or without culture and sensitivity
  • Thoracic (chest) and abdominal radiographs (x-rays)
  • Abdominal and or scrotal ultrasound
  • Plasma estrogen levels
  • Preputial swabs
  • Serum inhibin concentrations
  • Fine needle aspiration
  • Biopsy and histopathology (microscopic analysis of tissue) of removed testicle or tumor
  • Treatment of Sertoli Cell Tumor in Dogs

  • Surgical removal of the involved testes (orchiectomy)
  • Chemotherapy if the tumor has metastasized
  • Supportive care if associated disease conditions are present
  • Home Care and Prevention

    Watch the incision daily for any sign of swelling or discharge. The scrotal sack may be slightly swollen postoperatively, but the swelling should slowly resolve within a week or two.

    If skin sutures are used, they should be removed in 7 to 10 days. If your dog begins to lick the area excessively, an Elizabethan collar may be required.

    Seek veterinary care if your dog has a fever or feels ill postoperatively. If your dog had bone marrow hypoplasia due to a Sertoli cell tumor, close monitoring of blood tests will be required.

    An excellent preventive measure is to have your dog neutered (castrated) at an early age.

    In-depth Information on Sertoli Cell Tumor in Dogs

    Usually Sertoli cell tumors are found as incidental findings on a routine physical exam or an owner may notice a swelling on his dog’s testicle. In most cases, the tumor causes no clinical problems; however, Sertoli cell tumors have the potential to be malignant and may cause other serious disease conditions.

    Cryptorchid testicles with Sertoli cell tumors may become large enough to cause abdominal distention and pressure on other abdominal organs. This may cause abdominal discomfort or interference with internal organ function. Sertoli cell tumors may also produce excessive estrogen or decreased androgen production, which are changes in sex hormone concentrations. This increase in estrogen levels may lead to serious secondary conditions.

    One such condition is known as a male feminizing syndrome. About 25 percent of Sertoli cell tumors cause this syndrome, but the percentage is even greater if a cryptorchid tumor is involved. The elevated estrogen hormones cause the male dog to take on some female characteristics, as well as display other typical signs.

    The clinical signs associated with the feminizing syndrome include:

  • Enlargement of the mammary glands, possibly with the production of milk
  • Skin changes that follow a pattern typical of an “endocrine alopecia”: symmetrical hair loss starting in the hindquarters and genitalia
  • Increased skin pigmentation
  • Infertility
  • Decreased libido
  • A pendulous prepuce
  • Atrophy of the non-neoplastic testicle

    Prostatic enlargement and disease (squamous metaplasia and prostatitis) may additionally be seen due to the changes in hormone levels. A much more severe and potentially life-threatening condition associated with chronic (long standing) elevated estrogen levels and Sertoli cell tumors is estrogen-induced bone marrow hypoplasia.

    Elevated levels of estrogen have a toxic effect (estrogen toxicity) on the bone marrow, and bone marrow hypoplasia may develop where the cells in the bone marrow are damaged and cannot function properly. Since the cells in the bone marrow normally produce red blood cell, white blood cells and platelets (cells that help in clotting), decreases in all three cell lines may be seen (pancytopenia). This may lead to anemia (from the decreased red blood cells), infections (from the decreased white blood cells), and bleeding tendencies (from the decreased platelets). Bone marrow hypoplasia is the most serious potential sequelae of Sertoli cell tumors.

    Other diseases that have similar clinical symptoms as Sertoli cell tumors include:

  • Other testicular tumors. Interstitial cell tumors and seminomas are other testicular tumors that cause masses on the testes. Both tumors are usually benign, and require aspiration or biopsy to confirm diagnosis.
  • Orchitis and epididymitis. Inflammations of the testicle and epididymis, the tube-like structure along side the testicle, are usually caused by a bacterial infection. The condition generally is painful, and dogs tend to feel ill. Affected dogs may also have a fever. If the infection is severe, the swelling in the testicle may begin to spread up the scrotum and into the inguinal area. Epididymitis may sometimes be caused by Brucella infection.
  • Testicular torsion is a twisting of the testicle where blood supply and or lymphatic drainage is compromised. The testicle is usually symmetrically enlarged and painful. The condition is often associated with testicular neoplasia. Testicular torsions occur with greater frequency in abdominal cryptorchid testes.
  • A spermatocele also called a sperm granuloma may occur due to a cyst-like dilation of the epididymis. Sperm may become trapped inside the dilation, and an inflammatory response may occur. This response may produce a small swelling in the epididymis. It is a benign condition, but may result in infertility.
  • An inguinoscrotal hernia occurs when abdominal contents pass into the scrotal sac. Most commonly, it is fatty tissue or a loop of bowel that enters through the inguinal canal. It is not a common condition.
  • If the tumor is located on a cryptorchid testicle and abdominal distention is present, other causes of abdominal swelling would need to be considered, for example other intra-abdominal masses or fluid accumulation.
  • If the typical alopecia (hair loss) is present with the feminizing syndrome, causes of endocrine alopecia need to be considered. These include: thyroid, adrenal, and growth hormone disorders as well as other causes of estrogen imbalances including oral estrogen administration.
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