Kidney Cancer In Dogs

Kidneys are critical to canine health. These bean-shaped, abdominal organs serve the same basic functions as human kidneys, including filtering blood to eliminate waste, producing hormones, balancing certain chemical levels and helping control blood pressure. Unfortunately, the kidneys can also be a place where cancer originates. Fortunately, like humans, dogs are typically born with two kidneys and can live with one if removal of a kidney is indicated. Thankfully, kidney cancer is not common, affecting about 1% of dogs. In general, only one kidney is affected unless metastasis (spread) has occurred. Most dogs that develop kidney cancer are older, but one type — nephroblastoma — can strike younger dogs, including sometimes puppies less than a year old.

Kidney cancer in dogs can be treated but in many cases is not curable. As is the case with most cancers, an early diagnosis can lead to a better prognosis. Ideally, treatment would begin before metastasis occurs, because kidney cancer can spread to the liver, lungs, abdominal lymph nodes, the renal blood vessels and the vena cava (a large vein that carries deoxygenated blood to the heart). Thus, knowing both the physical and behavioral signs of kidney cancer in dogs can be very helpful for early detection.

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Types of Kidney Tumors in Dogs

There are a few different types of cancerous kidney tumors in dogs. (As an FYI, kidney tumors are also known as renal tumors — “renal” is the adjective for anything kidney-related.) Cancers that originate in the kidney are considered primary cancers and include:

• Carcinoma (forms in the lining and is the most common type)
• Adenocarcinoma (forms in glandular tissue)
• Nephroblastoma (forms in the kidney cells)
• Transitional cell carcinoma (forms in transitional cells)
• Renal cystadenocarcinoma (which is more common in German Shepherds but still rare overall; in addition to kidney tumors, a dog with renal cystadenocarcinoma can develop skin lesions)

Cancer can also originate elsewhere and metastasize to the kidneys in which case it is categorized as secondary kidney cancer. Among the most common examples is lymphoma.

Not all growths on a dog’s kidney are cancerous. A mass can also be a benign cyst, or general enlargement of the kidney may result from a renal infection.

Symptoms of Kidney Cancer in Dogs 

A dog with kidney cancer may display both behavioral changes and physical signs. Visible symptoms can include an enlarged abdomen, weight loss, blood in the urine, kidney insufficiency or kidney failure and, with renal cystadenocarcinoma, skin lesions. Behavioral signs of kidney cancer in dogs that you may notice include excessive drinking and urination, lethargy, poor appetite and abdominal  discomfort or discomfort near your canine’s back.

Diagnosing Kidney Cancer in Dogs

Other medical issues can cause some of the same symptoms as kidney cancer. For instance, an obstructed ureter (urinary duct) can make a kidney swell, enlarging the abdominal area. A kidney infection also can be the culprit, and suspected renal tumors in dogs could wind up being benign cysts.

In order to reach a diagnosis, a veterinarian will run a series of tests to collect as much information as possible. These can include:

• A complete blood count (CBC) and a blood chemistry profile: These tests can speak to a dog’s overall health and help determine how well the kidneys are functioning.
• Urinalysis: The contents and appearance of a dog’s urine also provide information about whether the kidneys are functioning properly.
• Kidney or urine culture: Bacteria is grown from a urine sample to help determine whether an infection is the cause of a kidney issue or if there is a secondary infection in addition to the cancer.
• Abdominal X-rays: X-rays help a veterinarian determine if the kidney is enlarged.
• Abdominal ultrasound: Ultrasounds provide even better imaging of soft tissues, giving a good look at the structures of the kidneys, to assess if there is a tumor present, and to assess the other organs (liver, abdominal lymph nodes, etc.) as well.
• Aspiration: A fine needle is used to remove a sample of cells, which are then examined by a pathologist to determine whether cancer is present.
• Biopsy: A portion of the tissue in question— or the entire tumor, if possible — is removed and sent to a pathologist for further testing.
• CT scan: If cancer is suspected or confirmed, this imaging procedure can provide much more detail than an X-ray or ultrasound, and a surgeon can use it to determine whether a kidney tumor or the kidney itself is removable, if the cancer has infiltrated into the surrounding blood vessels, and how best to surgically approach this area.
• Chest X-rays: Three-view chest X-rays are used to determine whether cancer has spread to the lungs.

Treatment and Prognosis 

Kidney cancer in dogs typically involves surgical removal of the affected kidney. On rare occasions, this can be curative. Other treatments may help slow down the cancer and improve a  dog’s quality of life, giving you more time together.

Surgery 

If only one kidney is affected and there has been no metastasis, surgical removal is the ideal choice to treat renal carcinoma in a dog — the most common type of primary kidney cancer — as well as other types. The prognosis depends in large part on whether the cancer was caught early.

Surgery is not indicated if both kidneys are affected.

Chemotherapy and/or Radiation

Chemotherapy is drug-based treatment often used when cancer is aggressive or if the cancer is more systemic as opposed to confined to a single mass. Renal lymphoma is an example of the latter.  Chemotherapy may be by an intravenous route or by pills given orally.

Radiation involves targeting cancerous cells with high-energy rays. There are two primary types of radiation: conventionally fractionated radiation therapy (CFRT) and the more advanced stereotactic radiation (SRS). The latter uses higher doses of radiation and fewer treatments — 1 to 3, vs. 15 to 21 with CFRT. At times, radiation therapy may be able to better treat a renal mass that cannot be safely or fully surgically excised.

Forgoing Treatment

If kidney cancer goes untreated, clinical symptoms will continue to progress. As the dog’s quality of life diminishes, a pet parent may face a decision about euthanasia.

PetCure Oncology Treats Kidney Cancer in Dogs

Expertise and extensive experience with a range of cancer treatment options are only part of what we offer at PetCure Oncology. Our mission is to provide compassion and understanding as well. If you have reason to believe that your beloved pet might have cancer of any type, be assured that we are here to determine the best treatment course to give your dog the best quality of life possible and extend your time together. For more information about our cancer treatment options, including SRS (which we specialize in), find a location near you and contact us today.

The contents of this article were provided in part by Dr. Renee Alsarraf, DVM, DACVIM (Oncology), a board-certified veterinary medical oncologist and member of PetCure Radiation Oncology Specialists (PROS).