Testicular cancer in dogs is the uncontrolled growth of cancer cells, resulting in a tumor within a dog's testicles. The early stages of testicular cancer in dogs can show no signs and localize before spreading to nearby tissues. A lump is noticeable, and the dog can experience discomfort as the cancer spreads to the lymph nodes in the groin area. 

Common signs of dog testicular cancer include a lump on the dog's testicle, dog swollen testicle, lethargy, weight loss, and changes in appetite. Testicular cancer primarily affects older, unneutered male dogs.

Consult a veterinarian immediately if a dog displays any signs. Testicular cancer care includes surgical removal of the affected testicle, which is highly effective if the cancer is detected early. Chemotherapy or radiation therapy are other care options, depending on the cancer's progression and metastasis. 

How common is Testicular Cancer in Dogs?

Testicular cancer in dogs is relatively common, and 27% of dogs develop tumors in the testicles. “The detection rate of testicular tumors in dogs is 16.8% in male canine tumors and 94.1% in male genital tumors, with cryptorchidism significantly affecting the incidence and type of these tumors,” according to the study by Liao, A., et al.titled “A 12-year retrospective study of canine testicular tumors,” 2009.

Boxers, Weimaraners, and German Shepherds are predisposed to a lump on dog testicle and testicular cancer. Neutering or castration in dogs under 6 months of age significantly reduces the risk of cancer in dogs. 

What are the early stage testicular cancer in dogs?

The early stages of testicular cancer in dogs are listed below. 

• Stage 0 or Carcinoma in Situ: The cancer can show no signs, and the abnormal cells are present but have not yet invaded deeper tissues. The cancer remains confined to the lining of the seminiferous tubules within the testicle.

• Stage I or Localized Tumor: A lump on the testicle is palpable, and there is a slight inflammation or asymmetry in the testicles, but the cancer is confined to the testicle and has not spread to nearby lymph nodes or other tissues. 

• Stage II: Regional Spread: The cancer begins to spread beyond the testicle to nearby tissues, including the epididymis or the spermatic cord in stage II testicular cancer. The lymph nodes or distant organs remain unaffected, although the dog’s testicle can be inflamed more, and discomfort increases. The dog shows systemic signs such as lethargy and decreased activity levels.

• Stage III: Lymph Node Involvement: Cancer cells have spread to regional lymph nodes, typically in the groin area, indicating advanced local spread without distant metastasis. The dog’s lymph nodes are inflamed, exhibiting signs such as weight loss, appetite changes, and general malaise.

Do Senior Dogs Get Testicular Cancer?

Yes, senior dogs get testicular cancer. The risk of developing testicular cancer increases as dogs age. Testicular cancer is prevalent in unneutered male dogs over 10 years old, making senior dogs particularly susceptible. Senior dogs are at increased risk of various cancers, such as melanoma, bone cancer, and lymphomas, due to prolonged exposure to different environmental factors and the natural aging process of their cells. 

“Mean age at diagnosis of testicular tumors in dogs was 10.7 ± 2.7, with similar values for different tumor types,” according to the study by Manuali, E., Forte, C., Porcellato, I., Brachelente, C., Sforna, M., Pavone, S., Ranciati, S., Morgante, R., Crescio, I., Ru, G., & Mechelli, L. titled “A five-year cohort study on testicular tumors from a population-based canine cancer registry in central Italy (Umbria),” 2020.

How is Testicular Cancer Different from Lymphoma in Dogs?

Testicular cancer is different from lymphoma in dogs because they affect different parts of the body and have distinct signs and care approaches. “Canine lymphoma is a neoplasm with 7 diagnostic categories: benign hyperplasia, low-grade B-cell, high-grade B- and T-cell, low-grade T-cell, centroblastic large B-cell, and high-grade peripheral T-cell,” according to the study by Valli, V.et al. titled “Canine Lymphomas,” 2013.

Testicular cancer primarily originates in the testicles, leading to signs like inflammation or lumps in the scrotum, discomfort, and enlarged lymph nodes. Lethargy, swollen lymph nodes in the groin, weight loss, and decreased appetite are signs of dog lymphoma, which affects the lymphatic system.

What are the signs of testicular cancer in dogs?

The signs of testicular cancer in dogs are listed below.

• Lump on the Testicle: A noticeable mass or lump on one or both testicles is often the first sign of early-stage testicular cancer in dogs.

• Swollen Testicle: A dog with an enlarged or swollen testicle that is firm or uncomfortable to touch is a sign of testicular cancer in dogs. 

• Asymmetrical Testicles: A testicle appearing larger or differently shaped than the other testicle is a sign of testicular cancer.

• Changes in Skin Color or Texture: The skin covering the testicles changes color or becomes ulcerated, a sign of testicular cancer in dogs.

• Lethargy: Decreased energy levels and general tiredness are signs of testicular cancer in dogs. 

• Weight Loss: Unexplained weight loss is a sign of testicular cancer in dogs.

• Changes in Appetite: Reduced interest in food or eating less than usual.

• Discomfort: The dog showing signs of discomfort, such as licking the area excessively, difficulty sitting, walking, or vocalizing discomfort, is a sign of testicular cancer.

• Feminization Signs: Dogs exhibit feminization signs such as enlarged mammary glands when they have testicular cancer due to hormone production by the tumor.

Is testicular cancer in dogs uncomfortable?

Yes, testicular cancer in dogs is uncomfortable, especially as the tumor grows or if it metastasizes to other body parts. Discomfort caused by testicular cancer includes acute discomfort from the tumor itself, chronic discomfort as the disease progresses, and neuropathic discomfort if nerves are affected. The discomfort impacts a dog's behavior, causing listlessness, aggressiveness, or withdrawal. It affects their appetite, sleep patterns, and quality of life.

 “The management of chronic testicular pain includes a careful assessment of testicular and extratesticular causes, non-surgical management, and, in some cases, orchiectomy,” according to the study by Kumar, P., Mehta, V., & Nargund, V. titled “Clinical Management of Chronic Testicular Pain,” 2010.

What does testicular cancer look like in dogs?

Testicular cancer in dogs looks like a noticeable lump or swelling on one or both testicles, accompanied by changes in testicle size or consistency. The lump becomes firm and irregularly shaped. The skin over the lump appears reddened or ulcerated, and in some cases, the tumor reaches a substantial size, causing the testicle to become notably enlarged. The texture of the affected testicle feels harder or more nodular because of the cancerous cells.

 “A large scrotal swelling in a dog is a common sign of malignant mesothelioma, a rare testicular cancer,” according to the study by Vascellari, M.et al. titled “Malignant Mesothelioma of the Tunica Vaginalis Testis in a Dog: Histological and Immunohistochemical Characterization,” 2011.

How to support testicular cancer in dogs?

The ways to support testicular cancer in dogs are neutering, avoiding environmental toxins like herbicides and insecticides, examining the dog at home, regular vet visits, and a healthy lifestyle. 

• Neutering: The most effective way to prevent testicular cancer in dogs is to neuter them. Neutering removes the testicles, Neutering dogs before they reach 6 months of age significantly reduces the risk of testicular cancer.

• Regular Veterinary Check-ups: Regular check-ups allow for early detection of testicular abnormalities.

• Self-Examination: Routinely checking the dog’s testicles for any changes, such as lumps, inflammation, or asymmetry, helps prevent testicular cancer. Consult a veterinarian immediately. 

• Healthy Diet and Lifestyle: Maintaining a healthy diet and lifestyle helps support the dog's health. A balanced diet and regular exercise contribute to a strong immune system and general well-being.

• Avoiding Exposure to Toxins: Minimizing exposure to environmental toxins and chemicals, such as pesticides and herbicides, 

What are the Care Options for Testicular Cancer in Dogs?

The care options for testicular cancer in dogs include surgery, chemotherapy, and radiation therapy. The care is tailored to the specific type and stage of the cancer. “Testicular cancer in dogs is treatable with orchiectomy, surgical resection, and cisplatin chemotherapy,” according to the study by Dhaliwal, R. et al. titled “Treatment of aggressive testicular tumors in four dogs,” 1999.

Chemotherapy is administered after the affected testicle(s) are removed to kill any cancer cells that have spread beyond the testicle. Chemotherapy protocols vary based on the type and stage of cancer. Radiation therapy is used to target and shrink tumors that cannot be surgically removed or to treat areas where the cancer has spread locally.  Palliative care focuses on managing signs and supporting the dog's quality of life in advanced cases where the cancer has spread extensively and is unable to be completely removed.