What is Kidney Cancer in Dogs?
Kidney cancer in dogs refers to the development of tumors within the kidneys, which are vital organs responsible for various functions such as blood filtration and nutrient balance. Dogs possess two kidneys positioned near the spine, serving similar roles to those in humans.
These tumors can either originate within the kidney itself (primary) or migrate from other parts of the body (metastatic). Primary kidney tumors are relatively uncommon, comprising less than 2% of all canine cancers and typically affecting only one kidney. Benign tumors, like papillomas and fibromas, are rare occurrences in canine kidneys.
Different types of kidney tumors exist, depending on their point of origin in the body:
- Carcinomas, the most prevalent primary kidney tumors, usually begin in epithelial tissue or skin.
- Adenocarcinomas, a malignant cancer type originating in glands.
- Sarcomas, which start in bones or muscles.
Metastatic tumors, such as renal carcinomas, often spread to other organs like the lungs, abdominal organs, or nearby lymph nodes. Renal carcinomas can also invade major blood vessels, like the caudal vena cava, leading to the formation of dangerous blood clots. These cancers predominantly affect older, medium to large male dogs.
Additionally, other primary tumors may develop in the kidneys, including transitional cell carcinoma, hemangiosarcoma, and nephroblastoma, which is a particularly aggressive congenital tumor often diagnosed in dogs under 12 months old.
Renal cystadenocarcinoma, a hereditary condition observed in German Shepherds, accounts for a notable portion of kidney tumors in the breed. It affects both kidneys and gradually impairs kidney function. This condition, also known as renal cystadenocarcinoma and nodular dermatofibrosis, often manifests with firm skin bumps on the dog’s legs and head around the age of six.
Symptoms
Symptoms of kidney cancers in dogs encompass various general signs, including:
- Abdominal pain
- Swollen belly (abdominal distension)
- Reduced appetite
- Weight loss
- Nausea
- Vomiting
- Lethargy
- Depression
- Occasional presence of blood in urine
Typically, veterinarians detect kidney tumors through physical examination, where they may notice enlargement or abnormal firmness in the kidney during routine annual check-ups.
Causes
The etiology of kidney cancer in dogs, like many cancers, remains largely unidentified. While cancers often arise due to environmental or genetic influences, currently, there are no identified environmental factors contributing to kidney cancer in dogs.
Diagnosis
Veterinarians employ several diagnostic methods to identify kidney cancer in dogs:
- Blood work, including blood chemistry and complete blood count, is routinely conducted to assess the overall health status of the dog, although abnormalities may not always be present.
- Urinalysis is performed to detect elevated protein levels or the presence of red blood cells, aiding in the diagnosis process.
- Abdominal X-rays serve as an effective screening tool, often revealing an enlarged affected kidney.
- Additional radiographs of the chest, spine, and legs may be recommended to screen for metastatic spread, influencing treatment decisions.
- CT or MRI scans may be advised for a more comprehensive assessment of tumor invasion into surrounding tissues, aiding in surgical planning.
- Abdominal ultrasound confirms kidney involvement and structural changes while identifying potential metastasis to other organs or lymph nodes.
- Fine needle aspiration (FNA) biopsy may be recommended, where a thin needle is inserted into the organ to collect a sample for further analysis, often guided by ultrasound.
Treatment
The primary treatment for kidney cancer in dogs typically involves surgical removal of the affected kidney along with the associated ureter, which transports urine from the kidney to the bladder. Surgical strategies depend on factors such as the type of tumor, presence of metastasis, and extent of invasion into nearby structures like the caudal vena cava.
Renal carcinoma, in particular, has shown resistance to chemotherapy, radiation therapy, and hormone therapy. Response rates to these treatments have been generally low, with less than 10% of renal carcinoma cases exhibiting any positive response to chemotherapy. Your veterinarian will devise a tailored treatment plan best suited for your dog’s condition.
Living and Management
- Resting: Your dog will need ample rest to recuperate from the surgery.
- Medications: Your veterinarian may prescribe medications such as anti-inflammatories, pain relievers, and antibiotics to aid in the recovery process.
- Follow-up visits: Regular follow-up appointments with your veterinarian are essential to monitor for any signs of disease recurrence, particularly in areas where metastasis may have occurred.
Kidney Cancer in Dogs FAQs
How long can a dog live after being diagnosed with kidney cancer?
Dogs without metastasis and successful removal of the affected kidney can survive for up to 4 years. However, the average survival time for dogs diagnosed with renal carcinoma is 8 to 16 months after diagnosis. This shorter average survival is due to challenges in tumor removal, high metastatic rates, and advanced disease stage at diagnosis.
How aggressive is kidney cancer in dogs?
Renal carcinoma is typically highly aggressive in dogs, with a high metastatic rate within the kidney. Metastasis commonly occurs, with 54% of dogs diagnosed with metastasis in their lungs or abdominal organs and 27% metastasized to lymph nodes. Other affected sites may include the heart, brain, and bones.
Is kidney cancer curable in dogs?
While dogs with no metastasis and successful kidney removal can have a favorable prognosis, there’s no definitive cure for kidney cancer in dogs.