Urinary tract neoplasia

• Neoplasms of the kidney - overview

  Uncommon, represent 0.5-1.7% of all neoplasms in dogs.

  Benign tumours uncommon (adenomas, lipomas, fibromas, and papillomas)

  Most common in middle-aged to older animals.

  No breed predilection has been found (except for heritable prediliction for the development of bilateral, multifocal cystoadenocarcinomas in German Shepherds, generally between 5-11 years of age.
• Neoplasms of the kidney - renal carcinoma

  Most common malignant tumour.

  Usually, it is unilateral, located at one pole of the kidney, and well demarcated.

  Size varies from microscopic to several times that of the normal kidney metastasises early to various organs; the opposite kidney, lungs, liver and adrenals are involved most commonly.
• Neoplasms of the kidney - Nephroblastomas

  Embryonal nephroma, Wilm’s tumour (arise from vestigial embryonic tissue).

  They are seen in young animals and, in dogs, are most commonly diagnosed at <1 year of age.

  There is no breed predilection.

  Males are affected twice as commonly as females.

  Nephroblastomas are usually unilateral but are occasionally bilateral.

  They can grow to an immense size; it is not uncommon to have virtually the entire abdomen accepted but the tumour, metastasises may occur to regional lymph nodes, liver and lungs.
• Neoplasms of the kidney - transitional cell carcinomas and others

  Transitional cell carcinomas arise from transitional epithelium of the renal pelvis, ureter, bladder or urethra.

  Other primary malignant renal neoplasms are uncommon and include haemangiosarcoma, fibrosarcoma, leiomyosarcomas and squamous cell carcinomas.
• Neoplasms of the kidney - lymphosarcoma

  Kidneys are a common site of metastatic or multi centric neoplasms.

  metastatic lesions may be unilateral or bilateral.

  Lymphosarcoma is the most common multi centric tumour involving the kidneys.

  As many as 50% of dogs and cats with lymphosarcoma have renal lesions and, in some cases, only the kidneys or kidneys and brain are affected.
• Neoplasms of the kidney - clinical signs

  Haematuria, dysuria, stranguria and pollakiuria are the most common signs.

  Animals with ureteral obstruction and unilateral hydronephrosis may show signs of abdominal pain and have a palpable, enlarged kidney.

  Signs of ureamia may be apparent in animals with bilateral ureteral obstruction and hydronephrosis or with urethral obstruction.

  The bladder wall may be thickened, and a cord-like urethra or urethral mass(es) may be palpable rectally.
• Neoplasms of the kidney - diagnosis

  History

  Clinical signs

  Ultrasonography

  Urinalysis

  Radiography (contrast)

  Computed tomography.
• Neoplasms of the kidney - treatment

  Treatment of majority of renal neoplasia except lymphosarcoma involves surgical removal.

  Unilateral nephrectomy is usually required.

  Lymphosarcoma is best managed by combination chemotherapy.

  Chemotherapy us generally ineffective against renal tumours other than lymphosarcoma.
• Neoplasms of the lower urinary tract - overview

  Neoplasms of the ureters, bladder and urethra are uncommon in dogs and rare cats.

  The low incidence in cats may be due to a difference in tryptophan metabolism that results in low urinary concentrations of carcinogenic tryptophan metabolites.

  The mean age of affected dogs and cats is 9 years.

  In the lower urinary tract, primary neoplasms are more likely to be malignant than benign.
• Neoplasms of the lower urinary tract - primary malignant neoplasms

  Among primary malignant neoplasms of the lower urianry tract, ransitional cell carcinomas are diagnosed most frequently in both species.

  Squamous cell carcinomas, adenocarcinomas, fibrosarcomas, leiomyosarcomas, rhabdomyosarcomas, haemangiosarcomas, and osteosarcomas also are found.
• Neoplasms of the lower urinary tract - transitional cell carcinomas

  May be solitary or multiple papillary-like projections from the mucosa or may develop as a diffuse infiltration of the ureter, bladder, prostate, and/or urethra.

  Cystic transitional cell tumours are more common in certain breeds of dogs, particular Scottish Terrier, habe been associated with prior therapy with cyclosphamide and may be linked to exposure to herbicide and older-generation insecticides.

  Transitional cell tumours are highly invasive and metastasise frequently, most commonly or the regional lymph nodes and lungs.
• Neoplasms of the lower urinary tract - clinical findings


  Ureteral and bladder neoplasms can cause chronic obstruction to urine flow with secondary hydronephrosis.

  Urethral tumours are more likely to cause acute obstructive uropathy.

  Intractable secondary bacterial urinary tract infections are commonly associated with neoplasms of the bladder and urethra.
• Neoplasms of the lower urinary tract - diagnosis

  History and clinical signs are highly suggestive of the lower urinary tract disease in animals with tumours of the bladder or the urethra.

  Urinalysis frequently reveals haematuria, and there may be evidence of secondary infection.

  Neoplastic cells may be found in the sediment, particularly with transitional cell carcinomas.

  For bladder tumours in dogs, the veterinary bladder tumour antigen test or the BRAF mutation test may be helpful, although false positive and negative do occur.
• Neoplasms of the lower urinary tract - treatment

  Excision of the tumour, if possible, is the most beneficial therapy.

  Transitional cell carcinomas are frequently located at the trigone of the bladder or in the urethra and may necessitate radical reconstructive surgery of the lower urinary tract.

  Prognosis is poor for these animals, even with surgery, because recurrence and metastasis occur rapidly.

  Radiation therapy/ and or chemotherapy with piroxicam, cisplatin, doxorubicin, vinblastine, chlorambucil or mitoxantrone will generally prolong the life of affected animals.
• Primary causes of male cats getting urethral obstruction

  Intraluminal:

  • Plugs
  • Uroliths
  • Sloughed tissue

  Mural or extraluminal

  • Neoplasms
  • Strictures
  • Anomalies
  • Reflex dyssynergia
• Perpetuating causing of urethral obstruction in male cats

  Intraluminal:

  • Sloughed tissues
  • Inflammatory cells and clots.
  • Increased production of mucoprotein

  Mural or extraluminal

  • Inflammatory swelling
  • Muscular spasm
  • Strictures.
• Iatrogenic causes of urethral blockages in male cats

  Tissue damage:

  • Retrograde flushing solutions
  • Catheter trauma
  • Catheter-induced foreign body reaction
  • Catheter-induced infection.

  Post-surgical dysfunction.
• Post-renal urinary tract obstruction results in?

  Severe azotaemia

  Hyperkalaemia

  Metabolic acidosis.
• How to immediately relieve urethral obstruction

  Urethral catheterisation

  Therapeutic cystocentesis
• Removal of urethral plugs

  Restrain of animal

  Use of muscle relaxants

  Use of reverse flushing solutions.

  • Walpole’s solution (buffered acetic acid) has a pH of 4.5
  • Acid solutions precipitate proteins, little or no effect on crystals other than struvite, little effect on uroliths

  Catheterisation.
• Localisation of urethral obstruction

  Probably best acheived by retrograde positive contrast urethocystography.

  • Survey abdominal films
  • Contrast studies
  • Abdominal ultrasonography.
• Surgical options for urethral obstructions

  Tube cystotomy and urethral stenting

  Perineal urethrostomy (based on Wilson-Harrison technique)

  Prepubic urethrostomy

  Subpubic urethrostomy (transpelvic urethrostomy)
• Complications of feline perineal urethrostomy

  Haemorrhage

  Wound dehiscene

  Subcutaneous urine leakage

  Urinary incontinence

  Urinary tract infection.

  Urethral (stoma) stricture