What Is Prostate Cancer (Prostatic Adenocarcinoma) in Dogs?
Prostate cancer, specifically prostatic adenocarcinoma, affects male dogs and originates in the prostate gland, situated near the bladder’s neck where the urethra exits. This gland produces seminal fluid. Prostate cancer in dogs results from uncontrolled growth of prostate gland cells, with adenocarcinoma being the most prevalent form. Typically, dogs are diagnosed with this cancer around the age of 10. Similar to men, older dogs might experience benign prostate enlargement.
The exact cause of prostatic adenocarcinoma remains unknown, although environmental factors and genetics are considered potential risk factors. Like other adenocarcinomas, prostatic adenocarcinoma is highly metastatic, with over 85% of affected dogs experiencing spread to other body parts. Common sites of metastasis include other regions of the urinary tract, lymph nodes, lungs, abdominal organs like the liver and spleen, as well as bone. Although rare, instances of metastasis to the brain and spinal cord have been reported.
Symptoms and Types
Prostate cancer in dogs often manifests through urinary tract symptoms primarily. The enlargement of the prostate gland exerts pressure on the urethra, resulting in abnormal urinary patterns like straining to urinate, frequent urination with small amounts of urine, presence of blood in urine, and even complete urinary blockage.
However, symptoms of prostatic adenocarcinoma may extend beyond urinary issues if the cancer spreads to other organs. Invasion into the bladder can cause additional complications such as bleeding, infections, and difficulties in urination. Moreover, obstruction of a ureter, the tube responsible for transporting urine from the kidneys to the bladder, can lead to potential kidney damage.
In cases where the prostatic mass becomes notably large, compression of the colon may occur, resulting in difficulties in defecation and abnormal stool appearance.
Metastasis
Metastasis is a common occurrence with this cancer type, as it tends to spread to nearby organs, including:
Lungs: Symptoms may include coughing, irregular breathing, potential fever, loss of appetite, and weight loss.
Bones: Metastasis to the bones can lead to lameness at the affected site. This may manifest as a limp in a specific limb, or potentially both hind limbs if the pelvis is the site of spread.
Brain or spinal cord: Metastasis to the brain or spinal cord can result in neurological dysfunction, such as difficulty walking and abnormal behavior.
Causes
The precise cause of canine prostate cancer remains unidentified, although both intact and castrated male dogs can develop prostatic adenocarcinoma. While certain risk factors like environment and genetics may be associated with the development of prostatic adenocarcinoma, the exact cause remains elusive. Research suggests a potential correlation between early neutering and an elevated risk of prostatic adenocarcinoma development.
Diagnosis
Diagnosing prostatic adenocarcinoma in dogs involves a comprehensive approach utilizing clinical signs, thorough physical examination, and diagnostic procedures.
Initial screening includes blood work and urinalysis. Blood tests may reveal signs of anemia or infection/inflammation, while urine analysis checks for abnormalities like blood, bacteria, inflammation, or cancerous cells.
Given the cancer’s metastatic nature, abdominal and chest radiographs (x-rays) are crucial. Abdominal x-rays can indicate prostate enlargement or mineralization, while pelvic and spinal bones are assessed for signs of metastasis. Chest x-rays are essential for identifying lung nodules, a common site of spread.
Advanced diagnostics like abdominal ultrasound or CT scans may be necessary. Ultrasound offers detailed examination of the prostate, nearby lymph nodes, urinary tract, and abdominal organs. While less common, CT scans provide detailed information about the prostate and potential metastatic sites.
Cytological samples obtained through catheterization, prostatic wash, or fine needle aspiration assist in diagnosing prostatic carcinoma. These samples aid in confirming the presence of cancer cells.
Treatment
Treatment options for prostate cancer in dogs depend on the stage of the disease:
In early stages without metastasis, surgical removal of the affected part of the prostate may be an option, followed by radiation therapy or chemotherapy.
When metastasis has occurred, palliative care becomes crucial. Palliative care aims to alleviate pain and manage clinical symptoms while enhancing the dog’s quality of life for as long as possible.
In cases of urinary obstruction, a stent can be inserted into the urethra to maintain urine flow. Surgery for advanced disease is risky due to potential complications, but radiation therapy might be considered in select cases.
Veterinarians may prescribe nonsteroidal anti-inflammatory drugs (NSAIDs) for pain relief and administer appropriate antibiotics for any urinary tract infections present. While chemotherapy is an option, its long-term effectiveness remains uncertain.
Recovery and Management
In cases where the disease is identified early, before metastasis, more aggressive treatment can be pursued to prolong survival. However, once the cancer has spread, the focus shifts to managing clinical symptoms until the disease becomes uncontrollable.
The prognosis for prostatic adenocarcinoma is generally unfavorable. Euthanasia might become necessary when the quality of life declines or clinical signs become uncontrollable.
Prostate Cancer in Dogs FAQs
What is the typical lifespan after a dog is diagnosed with prostatic adenocarcinoma?
- The survival duration varies based on whether treatment is initiated. Since diagnosis often occurs in advanced stages, survival is typically brief. Without treatment, euthanasia usually happens within a month of diagnosis. With treatment, average survival is approximately 7 months post-diagnosis.
How aggressive is prostatic adenocarcinoma in dogs?
- Canine prostatic adenocarcinoma displays high local aggressiveness and a significant metastatic rate.
Is prostatic adenocarcinoma curable in dogs?
- Prostatic adenocarcinoma is not curable, although surgical removal may be successful in certain cases.