Dogs and cats have two kidneys. These organs lie within the abdomen along side of the spine. The kidneys are essential filters that remove toxins and wastes from the blood. Kidneys produce a hormone that stimulates the bone marrow to make red blood cells. They also maintain the correct balance of water, various salts and minerals in the body. Each kidney is connected to the urinary bladder by a ureter, a tube for transport of urine.
Two types of kidney tumors exist: ones that originate from within the kidney and ones that have spread to the kidney from another tumor within the body. Tumors that originate within the kidney include renal carcinoma, renal adenocarcinomas, transitional cell carcinoma, sarcomas of varying types, and a tumor that originates from embryonic cells called a nephroblastoma. At the time of diagnosis of a kidney tumor, about 16% of them have evidence of spread of the tumor to the lungs.
Breeds most common to develop kidney tumors include Cocker Spaniels, Labrador Retrievers, Rottweilers, Golden Retrievers, German Shepherds, Miniature Poodles, Malamute, Springer Spaniel, and Shetland Sheepdogs. Male dogs develop this tumor Used with permission, Hill’s Pet Nutrition about 50% more commonly than female dogs and the average age of affected pets is 8.4 years. Patients with nephroblastomas tend to be much younger. Most common clinical signs in affected patients include bloody urine, a palpable abdominal mass, increased thirst, increased urination, lethargy, weight loss, vomiting, pain, and behavioral changes.
The diagnosis of a kidney mass is made on abdominal x-rays or abdominal ultrasound. Advanced imaging such as abdominal MRI or CT scan can be used to define the extent of the kidney tumor, but also may be used to determine if visible (macroscopic) metastasis is also present. Chest x-rays are used to identify visible (macroscopic) spread of the cancer; however, microscopic spread of the tumor to other organs cannot be detected with x-rays. Blood work and urine testing is done to ensure that the unaffected kidney is functioning normally and other internal organs are healthy.
Nephrectomy or surgical removal of a kidney is the best treatment for a kidney tumor, providing that the patient is not in kidney failure. An incision is made along the abdomen to expose the internal organs. The blood vessels and ureters of the affected kidney are tied off and the kidney is then removed.
While in our hospital, your companion will continue to receive intravenous fluids, electrolytes and in some cases plasma or an artificial plasma product called Hetastarch. Uncommonly, a blood transfusion may be necessary. Your companion will be carefully monitored in the intensive care and will be given narcotics to ensure a pain-free recovery. Most patients that have abdominal surgery leave our hospital within 24 to 72 hours.
In a study, which included 82 dogs, the average survival time following nephrectomy was 16 months, regardless of tumor type. Surgery increased survival of patients that had kidney tumors. In this report, patients that received chemotherapy survived a few months longer than patients receiving only surgery, however this was not found to be statistically significant. At the time of death of affected patients, 77% had evidence of spread of the tumor, in spite of treatments given to the patient.
In cats, the incidence of metastasis at the time of diagnosis was reported to be 64% for renal carcinomas and 100% for transitional cell carcinomas. Seemingly, the prognosis may be poorer for cats that have kidney tumors than dogs.
Learn more about this disease by contacting our Oncology service at your nearest BluePearl veterinary hospital. Here are our hospital locations.
© BluePearl Veterinary Partners 2012