Testicular Cancer in Dogs: Causes, Signs, and Treatment

4 min readDec 28, 2023

Testicular cancer is a common condition in intact male dogs, especially in older individuals. While the overall incidence of testicular cancer in dogs is relatively low due to early neutering, it is important to understand the causes, signs, and treatment options for this condition. In this comprehensive guide, we will explore the different types of testicular tumors, their clinical manifestations, and the prognosis associated with treatment.

Types of Testicular Tumors

There are several types of testicular tumors that can affect dogs. The three most common types are:

Seminomas: These tumors originate from germ cells responsible for sperm production. Seminomas are typically benign and have a low propensity to spread.
Interstitial (Leydig) Cell Tumors: Interstitial cell tumors develop from Leydig cells, which produce testosterone. These tumors are generally benign and often incidentally discovered.
Sertoli Cell Tumors: Sertoli cells help in the development of sperm. These tumors have a higher rate of spread compared to other testicular tumors and are more common in undescended testicles.

Other rare types of testicular tumors include embryonal carcinoma, lipoma, fibroma, hemangioma, chondroma, and teratoma.

Causes of Testicular Cancer

The exact cause of testicular cancer in dogs is still unknown. However, certain factors can increase the risk of developing this condition. Dogs with undescended testicles, which are retained in the abdomen or groin, are more prone to malignant tumors such as seminomas and Sertoli cell tumors. Older dogs, particularly those over the age of 10, are also more susceptible to testicular cancer.

Certain breeds have a higher predisposition to testicular tumors, including Boxer Dogs, German Shepherds, Afghan Hounds, Weimaraners, Shetland Sheepdogs, Collie Dogs, and Maltese.

Clinical Signs of Testicular Cancer

In many cases, dogs with testicular tumors do not show obvious clinical signs. However, there are several signs that may indicate the presence of a tumor. These signs include:

Swelling of one or both testicles
Generalized scrotal enlargement
Infertility in breeding dogs
Hair and skin changes, such as symmetrical hair loss, brittle hair, and poor hair regrowth
Thin skin and hyperpigmentation (darkening) of the skin
Inflammation along the midline of the prepuce
Nipple elongation and mammary enlargement
Penile atrophy and preputial swelling
Testicular atrophy of the unaffected testicle
Prostatic atrophy or enlargement
Anemia (pale gums)
Behavioral changes, including squatting to urinate, reduced sex drive, and attraction to other male dogs

It’s important to note that the clinical signs may vary depending on the type of tumor and its location.

Diagnosis of Testicular Cancer

Diagnosing testicular cancer involves a thorough physical examination, including palpation of the testicles for any abnormalities. Additional diagnostic tests may be necessary to confirm the presence of a tumor and assess its characteristics. These tests may include:

Complete blood count (CBC) to check for anemia
Biochemistry profile to evaluate organ function
Urinalysis for concurrent bladder infection
Chest and abdominal radiographs (x-rays) to assess for tumor spread
Abdominal and scrotal ultrasound to visualize the tumor and its extent
Fine needle aspiration or biopsy to obtain a tissue sample for examination under a microscope

In some cases, additional imaging techniques such as CT scans may be recommended to determine if the tumor has spread to other organs or lymph nodes.

Treatment Options for Testicular Cancer

The primary treatment for testicular tumors is surgical removal of the affected testicles, known as castration. This procedure is typically curative for most testicular tumors. It is important to remove the scrotal skin as well to prevent postoperative complications such as swelling.

In cases where the tumor has metastasized or spread to other parts of the body, additional treatment options may be considered. These options include chemotherapy and radiation therapy. The choice of treatment will depend on the specific characteristics of the tumor and the overall health of the dog.

Prognosis for Dogs with Testicular Cancer

The prognosis for dogs with testicular cancer is generally favorable, especially when the tumor is diagnosed early and treated promptly. Surgical removal of the testicles is curative for most cases, with a high chance of complete recovery. However, approximately 10 to 20% of cases may have already experienced tumor spread at the time of diagnosis.

The prognosis varies depending on the type of tumor, its location, and the presence of metastasis. Sertoli cell tumors and interstitial cell tumors without spread or bone marrow damage have an excellent prognosis. Seminomas without signs of hyperestrogenism also have a positive prognosis.

It is essential to closely monitor dogs that have undergone treatment for testicular cancer for any signs of recurrence or metastasis. Regular follow-up appointments and diagnostic testing may be necessary to ensure early detection of any potential complications.

Conclusion

Testicular cancer is a relatively common condition in intact male dogs, particularly in older individuals and certain breeds. Understanding the causes, clinical signs, and treatment options for this condition is crucial for early detection and successful management. If you suspect that your dog may have testicular cancer, consult with your veterinarian for a thorough examination and appropriate diagnostic testing. With prompt treatment, the prognosis for dogs with testicular cancer is generally positive, offering a high chance of complete recovery and improved quality of life.