The dog presents for progressive worsening PU/PD and generalized weakness for four to five weeks. The dog is showing anorexia and vomiting thick yellow bile since last evening. The dog has collapsing episodes in the rear legs. Therapy has included NPO for two days, intravenous fluids and metoclopramide.
Physical examination: The findings include rectal temperature 100.6° F, heart rate 100/min, respiratory rate 35/min, pink mucous membranes, normal capillary refill time, and normal heart and lung sounds. The dog is stumbling and has mild nystagmus of variable intensity.
Laboratory results: A complete blood count, serum chemistry profile and urinalysis were performed and are included in Table 1.
Radiograph examination: The lateral thoracic radiograph is normal. The abdominal radiographs show a slightly small liver, cranial displacement of the stomach, and an enlarged and abnormally shaped left kidney. The right kidney appears to have a normal shape and size. Osteoarthritis is present in the coxofemoral joints and stifles.
Ultrasound examination: Thorough abdominal ultrasonography was performed. The dog was positioned in dorsal recumbency for the ultrasonography.
My comments: The liver is small and shows an inhomogeneous texture. Some small, round, hypoechoic lesions are present in the right lateral liver lobe.
No obvious masses noted within the liver parenchyma. The gall bladder is mildly distended, and its walls are not thickened or hyperechoic. The gall bladder does contain some sludge material. The spleen shows an inhomogeneous texture - no cancerous masses noted.
The left kidney is enlarged, shows mixed echogenicity, and has an abnormal shape. A large echogenic round lesion with low- to medium-echoes are present in the cranial renal pole of the left kidney.
The right kidney is normal in size and shape, and shows an inhomogeneous texture. No calculi were noted in either kidney. The urinary bladder is distended with urine and contains some urine sediment material - no masses or calculi noted. The wall of the urinary bladder may be slightly thickened. The left and right adrenal glands are similar in size and shape. The stomach, small intestines and colon are normal. The pancreas shows an inhomogeneous texture.
Ultrasound-guided fine needle aspirations of this renal mass for cytologic examination or ultrasound-guided renal mass biopsies for histopathologic examination are warranted to confirm renal carcinoma.
However, exploratory laparotomy for direct viewing of the left kidney for the potentially neoplastic mass and inspecting the liver surfaces for possible metastatic disease would be preferred. I would expect that this dog's left kidney and ureter needs to be surgically removed and histopathologic examination of the kidney mass done.
The dog's reported stumbling could be because of existing hypertension associated with the observed polycythemia (hemoconcentration) and renal mass. Definitely, the dog's blood pressure needs to be monitored before, during and after surgery for potential hypertension. Another reason for the dog's stumbling could be immune-mediated joint disease secondary to the existing renal mass.
Once the renal mass is removed, the joint disease usually will resolve. If the renal mass is confirmed as a renal carcinoma, one should follow the surgery with chemotherapy for potential metastatic disease.
Also, because of the dog's small liver size, prior to surgery fasted baseline and two-hour postprandial serum bile acids should be done to assess the dog's current liver function.
Renal tubular cell carcinoma in dogs Renal tubular cell carcinoma is the most common primary malignant neoplasm of the kidney in dogs. Benign and metastatic neoplasia may also occur in the kidneys too.
Neoplasms of the renal pelvis are usually associated with local signs such as hematuria and hydronephrosis, which precedes polysystemic signs.
Polycythemia is seen in dogs with renal tubular cell carcinomas that elaborates excessive quantities of erythrocyte-stimulating factor. Even though both kidneys may be involved, a sufficient quantity of functional renal parenchyma may persist to prevent signs of renal failure. Extensive bilateral involvement of the kidneys that destroy 70-75 percent or more of the nephrons is associated with signs of progressive renal insufficiency.
Survey abdominal radiographs often allow visualization of an abdominal mass and can be confirmed with abdominal ultrasonography. histopathologic examination of affected tissue is required for a definitive diagnosis and to determine tumor cell type. Thoracic radiographs should be done to check for potential metastatic disease.
In case of unilateral renal involvement, exploratory laparotomy is performed and biopsy tissue is obtained by nephrectomy. The abdomen is also explored for potential metastatic disease too.
If the tumor has not metastasized, and the opposite kidney is not neoplastic and has adequate function, nephrectomy and partial ureterectomy are warranted. If regional lymph nodes are enlarged and appear abnormal, systemic dissection and excision of regional lymph nodes is advised to prevent incomplete removal of tumor cells within the lymphatics.
Chemotherapy with adriamycin and/or carboplatin may be used for metastatic disease. Actual survival times from such chemotherapy is lacking in veterinary literature. Prognosis for primary malignant renal neoplasms undergoing unilateral nephrectomy for renal tubular cell carcinomas is good for six months to one-year survival. Some dogs have had good quality of life for up to four years until regrowth of the tumor occurred. Of course, these dogs were diagnosed early with their renal disease.