13 The haematuric/stranguric/dysuric cancer patient
Haematuria is defined as the presence of excessive numbers of erythrocytes within the urine and therefore from a cancerous disease viewpoint, haematuria can be caused by neoplasia existing potentially anywhere within the urinary tract. Stranguria usually indicates an obstruction in the lower urinary tract whilst dysuria can be suggestive of either an obstructive lesion or a neurological dysfunction. Cancer causing any of these clinical signs therefore could theoretically be located in a number of different anatomical locations and a logical step-wise approach should be taken to enable an accurate diagnosis to be made as quickly as possible.
The dog was taken to surgery for unilateral nephrectomy. Once anaesthetized the dog was placed in dorsal recumbency and the skin was routinely prepared. A ventral midline incision was made and the wound held open with a Balfour retractor. The abnormal left kidney was exposed by lifting the descending colon and moving it to the right, thereby using the mesentery attached to this to hold the small intestine towards the right hemiabdomen. The overlying peritoneum was incised and then manually peeled away from the kidney, using electrocautery to prevent any haemorrhage. The perirenal fat was then reflected to expose the renal vasculature and the ureter. The renal artery and vein were then identified and separated and then individually ligated using 3-0 silk before being transected. The ureter was then isolated and ligated close to the urinary bladder before being transected as well and the kidney removed (Fig. 13.1). The abdomen was then lavaged and closed routinely.
Postoperatively the dog was managed with opioid analgesia (methadone for 12 hours, buprenorphine for 24 hours) along with NSAID medication (carprofen 2 mg/kg BID for 5 days) and she recovered well. No gross haematuria was noted but microscopic haematuria was noted for 3 days.
Cancer of the kidney as a primary disease is actually rather unusual in the dog; indeed renal tumours are more likely to be secondary metastatic tumours than primary disease. This, therefore, leads to the necessity in any patient in whom a renal tumour is suspected for a thorough presurgery evaluation and staging to ensure that there is not a primary tumour elsewhere, as well as trying to establish the extent and severity of the disease. If a primary renal tumour is suspected in a dog, then the majority will be carcinomas (of which there are several different types), but lymphoma can also be seen and this can be bilateral in nature. Bilateral carcinomas were only reported in 4% of cases in a recent multicentre study. More unusually, other tumour types have been reported. In cats, lymphoma is the most common renal tumour type reported.
The clinical signs associated with renal neoplasia can be quite non-specific and haematuria that is noticed by the owner, as in this case, is actually not always reported although microscopic haematuria will frequently be identified. Weight loss, lethargy and inappetance are commonly reported, so a careful clinical examination is required to evaluate the size and shape of both of the kidneys, as identification of a palpable abdominal mass is often the first indication of a serious problem. Animals with renal lymphoma will usually have obviously enlarged kidneys with an irregular outline whereas, as in this case, unilateral renal enlargement due to a tumour may affect only one pole of one kidney.
The clinical pathology findings are also often non-specific. The finding of haematuria in the case reported here is reported in approximately 50% of cases, causing regenerative blood loss anaemia in approximately 33% of patients.
Diagnostic imaging, and in particular ultrasound, therefore, is a very important and useful tool to help establish the diagnosis. Ultrasound-guided aspirates or Tru-cut biopsies can be obtained, although in general the authors will only request an aspirate if lymphoma is suspected. Abdominal ultrasound is also very useful to look for local and visceral metastasis and also to assess whether or not the tumour has broken through the renal capsule to invade the surrounding musculature or vasculature. Whilst local invasion of a primary renal tumour does not prevent surgical excision, it will complicate the surgery, so attempting to establish the extent of the tumour in its locality is a very important function of the ultrasound scan. Radiographs are important to establish whether or not there are pulmonary metastases present and also to look for bony metastases in a patient that may have unexplained discomfort. Renal carcinomas (in common with most carcinomas) certainly have the potential to establish bony secondaries and although not common, will cause significant bone pain which may be difficult to treat. The author (RF), however, has had some success treating bone metastasis with a combination of meloxicam and oral bisphosphonates, in terms of producing good short-term analgesia and restoring quality of life for a limited period. There has been a recent case report of a dog with a transitional cell carcinoma of one renal pelvis causing hypertrophic osteopathy and this dog presented with haematuria and a reluctance to move. Surgical excision of the tumour led to a resolution of all the clinical signs and no further limb pain.
Unless lymphoma is diagnosed, or there are multiple secondary tumours identified, the treatment for renal neoplasia is complete nephrectomy and the diagnosis confirmed by histopathology. The prognosis does vary depending to some degree on the type of tumour identified; in a study of 82 dogs with renal tumours the median survival time for dogs with carcinomas was 16 months (range 0–59 months), for dogs with sarcomas it was 9 months (range 0–70 months), and for dogs with nephroblastomas it was 6 months (range 0–6 months). Interestingly, although not a common diagnosis, renal haemangiosarcoma is associated with relatively longer survival times when compared to other visceral forms of haemangiosarcoma (median survival time of 278 days with a range 0–1005 days in a case series of 14 dogs treated with surgery alone). However, in general, the problem with renal tumours is that they are usually highly malignant, they are frequently diagnosed quite late in their disease course and the tumours usually show very little response to chemotherapy (unless the diagnosis is one of lymphoma), so surgical excision is currently the only realistic treatment for non-lymphoid renal neoplasia.
The dog remained well with no evidence of further disease for 19 months, when she re-presented with exercise intolerance and lethargy. On examination she was moderately tachypneoic and sadly thoracic radiographs revealed the presence of multiple pulmonary metastases, so she was euthanized. However, with a disease-free period of 19 months after the diagnosis, she had a longer than average survival and a normal quality of life in this period.
Renal lymphoma is the most common renal tumour found in cats but it is not the most common form of feline lymphoma reported. The disease presents usually in a similar way to that seen in the cat reported here; quite non-specific signs with usually obvious bilateral renomegaly are apparent on abdominal palpation.
In cats, haematuria could be missed unless the animal uses a litter tray, so renal neoplasia in felines is often detected when the cat presents to investigate other signs such as lethargy or inappetance.
The diagnosis can usually be made using ultrasound-guided fine needle aspiration but it is important to remember that this will cause some degree of renal haemorrhage, so at least an accurate platelet count should be obtained before aspiration is performed. The ultrasonographic appearance of the kidneys can be very suggestive of lymphoma and a study has suggested that there is a significant association between hypoechoiec subcapsular thickening and renal lymphoma. The positive predictive value of hypoechoeic subcapsular thickening for lymphosarcoma in the study was 80.9%, the negative predictive value was 66.7%. The sensitivity and specificity of hypoechoiec subcapsular thickening for the diagnosis of renal lymphosarcoma were 60.7% and 84.6%, respectively.
The treatment for renal lymphoma for both dogs and cats is not surgery but chemotherapy. By the WHO classification, renal lymphoma is stage V and so variable responses have been reported but this case shows that it is always worth attempting treatment if the cat is relatively well. There are no studies to show a marked difference in efficacy between protocols, but a study from the Netherlands suggests that a COP-based protocol in cats for any form of lymphoma may be more successful than it is in dogs, with a complete remission rate of 75% being reported along with estimated 1- and 2-year disease-free periods (DFPs) in the cats with CR of 51.4 and 37.8%, respectively, and a median duration of remission was 251 days. The overall estimated 1-year survival rate in all cats with lymphoma was 48.7%, and the 2-year survival rate was 39.9%, with a median survival of 266 days. The cat reported in this case far exceeded what the attending clinician had expected in terms of success but the owner was delighted!