Canine Testicular Tumors

At Animal Cancer Care Clinic (ACCC), we understand that receiving a diagnosis of a testicular tumor in your dog can be a significant concern. Please know that our dedicated and compassionate team is here to support you and your furry companion every step of the way. Testicular tumors are common in intact (unneutered) male dogs, and while many are benign, some can be malignant and impact your dog’s health. We have advanced diagnostic and treatment options available at ACCC aimed at effectively managing this condition and maximizing your dog’s quality of life.

What are Canine Testicular Tumors?

Testicular tumors are abnormal growths that develop within the testicles. These tumors are most commonly found in intact (unneutered) male dogs, particularly as they age.

Several different types of testicular tumors can occur, and it’s important to distinguish between them, as their behavior (benign vs. malignant) and potential for spread vary:

• Interstitial Cell Tumor (Leydig Cell Tumor):
  • Most common type of testicular tumor.
  • Usually benign (non-cancerous) and rarely metastasize.
  • They arise from the interstitial (Leydig) cells, which produce testosterone.
  • Often appear as single or multiple spherical masses within the testicle.
• Sertoli Cell Tumor:
  • Less common than interstitial cell tumors.
  • Can be benign or malignant, with malignant forms having the potential to spread (metastasize) to regional lymph nodes (inguinal, sublumbar), and occasionally to the liver, spleen, or lungs.
  • They arise from Sertoli cells, which support sperm development.
  • These tumors are notorious for sometimes producing estrogen (a female hormone), leading to a condition called “feminization syndrome.”
• Seminoma:
  • Arises from the germ cells (sperm-producing cells).
  • Can be benign or malignant, with malignant forms potentially spreading, though metastasis is less common than with aggressive Sertoli cell tumors.
  • Often appear as firm, white-to-gray masses.

It is possible for a dog to have more than one type of tumor in the same testicle or in different testicles.

What Causes Canine Testicular Tumors?

The most significant risk factor for the development of testicular tumors in dogs is:

• Cryptorchidism (Undescended Testicles): This is when one or both testicles fail to descend into the scrotum and remain in the abdomen or inguinal canal. Testicles retained within the body are exposed to higher temperatures, which significantly increases their risk of becoming cancerous (especially Sertoli cell tumors and seminomas) by as much as 10-14 times compared to normally descended testicles. Tumors in undescended testicles are also more likely to be malignant. Neutering cryptorchid dogs is highly recommended to prevent tumor development.
• Age: Testicular tumors are more common in middle-aged to older intact male dogs, typically over 6 years of age.
• Breed Predisposition: Certain breeds may have a higher incidence of testicular tumors, including Boxers, German Shepherds, Weimaraners, Shetland Sheepdogs, Siberian Huskies, and Norwegian Elkhounds. Cryptorchidism also has a genetic component and is more common in some breeds.

Canine testicular tumors are not contagious to other pets or humans.

Signs and Symptoms of Canine Testicular Tumors:

The signs and symptoms of testicular tumors in dogs can vary depending on the tumor type, size, and whether it’s causing hormonal changes or metastasis:

• Scrotal Swelling or Firmness: This is the most common sign. You may notice one or both testicles are enlarged, firm, or irregular in shape.
• Changes in Testicle Consistency: The affected testicle may feel harder or softer than normal.
• Pain or Discomfort: The testicle or scrotum may be painful to the touch, or your dog may show reluctance to be handled in that area.
• Licking at the Scrotum: Excessive licking may indicate irritation or discomfort.
• Signs of Feminization Syndrome (primarily with Sertoli Cell Tumors): If the Sertoli cell tumor produces excess estrogen, you may observe:
  • Enlarged Nipples
  • Symmetrical Hair Loss (alopecia), often on the flanks, abdomen, or chest.
  • Pendulous Prepuce (enlarged sheath covering the penis).
  • Attention From Other Male Dogs
  • Bone Marrow Suppression (rare but serious complication, leading to anemia, low white blood cell count, and bruising/bleeding).
• Signs of Metastasis (Less common but possible with malignant tumors):
  • Enlarged Regional Lymph Nodes (in the groin or abdomen).
  • Abdominal Distension (if spread to abdominal organs).
  • Lethargy, Weight Loss, Decreased Appetite (generalized signs of advanced cancer).

If you notice any changes in your dog’s testicles or any of the associated symptoms, it’s important to seek veterinary attention promptly.

How are Canine Testicular Tumors Diagnosed?

Diagnosing canine testicular tumors typically involves a comprehensive approach:

• Physical Examination: Our veterinarians will perform a thorough physical examination, including careful palpation of both testicles (if descended) and the scrotum, as well as the regional lymph nodes. For cryptorchid dogs, we will attempt to locate the undescended testicle(s).
• Abdominal Ultrasound: For undescended testicles, an abdominal ultrasound is essential to locate the retained testicle(s) and assess their size, appearance, and the presence of any masses. It can also be used to evaluate regional lymph nodes and other abdominal organs for metastasis.
• Fine Needle Aspirate (FNA): An FNA may be attempted on accessible scrotal masses to collect cells for preliminary examination (cytology). However, FNA is often not definitive for testicular tumors, and a full biopsy may be required.
• Biopsy (Histopathology): A definitive diagnosis of the tumor type (interstitial cell tumor, Sertoli cell tumor, seminoma) and whether it is benign or malignant, requires a biopsy. Often, this means surgical removal of the affected testicle(s) (castration), which serves as both a diagnostic and therapeutic procedure. The removed tissue is then submitted to a specialized pathologist for microscopic examination.
• Blood Work: A complete blood count (CBC) and serum chemistry panel are performed to assess your dog’s overall health and organ function. For dogs with feminization syndrome, blood work may reveal bone marrow suppression (anemia, low white blood cells, low platelets).
• Hormone Testing: While not always definitive for diagnosis, hormone levels (e.g. estrogen) may be measured if feminization syndrome is suspected.
• Staging (for Malignant Tumors): If histopathology confirms a malignant tumor, further staging tests are recommended to check for metastasis:
  • Thoracic Radiographs (X-rays) or CT Scan of the Chest: To check for spread to the lungs.
  • Abdominal Ultrasound or CT Scan of the Abdomen: To check for spread to abdominal lymph nodes, liver, or other organs.

Treatment Options for Canine Testicular Tumors:

At Animal Cancer Care Clinic, the primary treatment for canine testicular tumors is surgical removal of the affected testicle(s), along with addressing any undescended testicles.

• Castration (Orchiectomy): This is the definitive treatment for testicular tumors.
  • For tumors in normally descended testicles, a standard castration is performed.
  • For tumors in undescended (cryptorchid) testicles, surgery involves locating and removing the retained testicle(s) from the abdomen or inguinal canal. Surgical removal effectively eliminates the primary tumor, prevents further growth, and resolves any hormone-related syndromes (like feminization). For benign tumors, surgery is usually curative.
• Chemotherapy: The role of chemotherapy for malignant testicular tumors is limited, as many do not respond well to traditional chemotherapy drugs. It may be considered in very specific situations, such as:
  • If metastasis is confirmed.
  • For highly aggressive or anaplastic (poorly differentiated) tumor types.
  • If complete surgical removal is not possible. Our veterinary oncologists at ACCC will discuss whether chemotherapy is recommended for your dog’s specific case.
• Radiation Therapy: Radiation therapy is generally not a primary treatment for testicular tumors. It may be considered in rare cases for local control of tumors that cannot be completely removed, or for metastatic sites, but its use is limited.
• Palliative Care: For dogs with advanced metastatic disease where aggressive treatment is not feasible, palliative care focuses on managing symptoms and maintaining the best possible quality of life.

What to Expect During and After Treatment:

If your dog undergoes treatment for a testicular tumor, you can expect:

• Pre-Surgical Assessment: Careful evaluation to ensure your dog is a good anesthetic candidate.
• Surgical Recovery: Post-operative pain management and monitoring of the incision site. Dogs typically recover quickly from castration.
• Resolution of Hormonal Signs: If feminization syndrome was present, signs such as hair loss or enlarged nipples usually resolve over weeks to months after the tumor is removed. Bone marrow suppression, if severe, may require additional supportive care.
• Regular Follow-Up Appointments (for malignant tumors): For dogs diagnosed with malignant testicular tumors, regular physical examinations and potentially repeat imaging studies (chest radiographs, abdominal ultrasound) will be recommended to monitor for recurrence or metastasis.

Prognosis for Canine Testicular Tumors:

The prognosis for dogs with testicular tumors varies significantly depending on the tumor type, whether it was cryptorchid, and the presence of metastasis:

• Benign Tumors (Most Interstitial Cell Tumors, many Seminomas, some Sertoli Cell Tumors): The prognosis is excellent with complete surgical removal. Castration is curative.
• Malignant Tumors: The prognosis is more guarded if the tumor is malignant and has a high potential for metastasis.
  • Seminoma: Even if malignant, metastasis is less common, and prognosis with surgery is often good.
  • Sertoli Cell Tumor: If locally invasive or has metastasized, the prognosis is more guarded. The presence of feminization syndrome itself does not necessarily indicate a worse prognosis for life, but severe bone marrow suppression can be life-threatening if not addressed.
• Cryptorchid Testicles: Tumors in undescended testicles are more likely to be malignant and therefore carry a more guarded prognosis if metastasis has occurred.

Overall, due to the high prevalence of benign forms and the effectiveness of surgical removal, the prognosis for most dogs with testicular tumors is generally favorable, especially with early detection.

We will discuss the potential prognosis for your dog based on their individual diagnosis and the chosen treatment plan at ACCC. Our goal is to provide realistic expectations while focusing on maximizing their comfort and quality of life for as long as possible.

Coping with a Testicular Tumor Diagnosis:

Receiving a diagnosis of a testicular tumor for your dog can be a source of concern. Please know that the team at ACCC is here to offer not only the best possible medical care for your dog but also compassionate support for you and your family during this time.

We encourage you to ask us any questions you have and to share your feelings and concerns openly. We want you to feel informed and supported as you make important decisions about your dog’s care.

Our commitment is to work with you to develop a treatment plan that is tailored to your dog’s needs and your wishes, while always prioritizing their comfort, health, and your shared bond.

Questions to Ask Your Veterinarian:

To help you better understand your dog’s condition and the treatment options available, here are some questions you may find helpful to ask us:

• What type of testicular tumor does my dog have? Is it benign or malignant?
• Was the affected testicle undescended (cryptorchid)?
• Has the tumor caused any hormonal imbalances (e.g. feminization syndrome)? If so, how severe is it?
• Has the cancer spread to regional lymph nodes or other parts of the body (e.g. lungs, liver)?
• What are the recommended treatment options for my dog’s testicular tumor?
• What are the potential risks and complications of surgery (castration)?
• Is chemotherapy or other therapy recommended after surgery? What are its goals and potential side effects?
• What is the expected prognosis for my dog with the recommended treatment?
• How will my dog’s comfort and quality of life be maintained?
• What is the estimated cost of the recommended treatment plan and ongoing care?
• What can I do at home to best support my dog during this time?

Conclusion:

At Animal Cancer Care Clinic, we are dedicated to providing compassionate and comprehensive care for dogs with testicular tumors. Our experienced team will work closely with you to develop a personalized treatment plan focused on managing the disease and maximizing your dog’s quality of life. Please do not hesitate to reach out to us with any questions or concerns you may have. We are here to support you and your cherished canine companion through this challenging journey.