Renal cancer is a type of cancer that affects the kidney and can either originate within the organ or metastasize (spread) from another part of the body. Renal tumors are not common in dogs, though the majority of primary renal tumors are cancerous. These typically affect middle-aged or older dogs, but cases have been noted in younger animals.

Malignant renal tumors can occur in one or both kidneys, developing either within the kidney or metastasizing from other areas of the body. These tumors are not common in dogs but require the affected kidney to be removed. Since kidney cancer may lead to acute renal failure, early detection is vital for a better prognosis.

Some dogs do not exhibit symptoms of kidney cancer, though they may begin to show signs as the disease grows. These include:

If the kidneys begin to fail, the dog may develop additional symptoms such as:

Much as with other cancers, little is known about the causes of kidney cancer in dogs. The cancer most commonly appears in middle-aged to older animals and may develop in the kidney itself or spread from other organs. Dogs of both sexes are equally susceptible to renal cancer, though this type of cancer is rare overall. There is no correlation between the cancer and breed except in the German Shepherd, which is predisposed to a syndrome of renal cystadenocarcinomas.

If your dog is exhibiting unusual behavior, visit the veterinarian immediately. Many of the symptoms of kidney cancer are not specific to the disease, which is why a close examination by the veterinarian is vital for an accurate diagnosis.

At the initial visit, blood work and urine sampling is usually performed to establish the dog’s ability to tolerate treatment, as well as to develop a clearer picture of the patient’s overall health. The veterinarian may opt to do a needle aspirate or biopsy of the tumor if kidney cancer is found. In order to determine the extent of the cancer, a thorough evaluation may be conducted, which may include:

These tests help establish the size of the tumor and determine the presence of metastasis to other areas of the body. Depending on the results, further tests may be necessary to ensure that other organs are healthy. The veterinarian may also perform function tests on the unaffected kidney.

Treatment varies depending on several factors, all of which will have been determined during the diagnosis stage.

Nephrectomy, or surgical removal of the affected kidney, is the recommended treatment for most renal cancer that has not spread to other parts of the body. Surgery is only a viable option if the second kidney is functioning properly and if your dog is strong enough to withstand the operation. Your dog can live a normal life with one kidney, and surgery may remove the cancer entirely, depending on the extent of the tumor. Metastasis or recurrence may still be possible months after nephrectomy.

If the cancer affects both kidneys or has metastasized to other areas of the body, rendering a nephrectomy infeasible, chemotherapy may be used to help combat the spread of the tumors and prolong your dog’s life. Your veterinarian can administer a potent combination of drugs, limiting the cancer’s spread to other organs. However, there is little documentation to support chemotherapy’s effectiveness against most primary renal tumors.

Kidneys remove waste from the blood. When the organ fails or does not function at full capacity, toxins build up within the body and will need to be removed by other means. IV fluids help remove those toxins. Additional care may be recommended to reduce pain, ensure hydration, and treat anemia, depending on how quickly the cancer has spread.

If your dog successfully underwent surgery and had the affected kidney removed, your veterinarian will provide you with aftercare instructions to follow. Pain medication helps keep your dog comfortable during recovery, and antibiotics prevent infections. Administer all medication as directed by your veterinarian, and limit physical activity over the next two or three weeks to ensure that the surgical site heals properly. General blood work and ultrasounds or radiographs may be recommended as follow ups to monitor metastatic disease.

A combination of home and veterinary care is important, whether or not nephrectomy was performed. Though prognosis is poor for most malignant renal tumors, particularly those that affect both kidneys, you may still maintain your dog’s quality of life for the remaining months with your veterinarian’s help.