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Neoplasms of the Lower Urinary Tract |  |
| Neoplasms of the ureters, bladder, and urethra are uncommon in dogs and rare in 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 yr. |
| In the lower urinary tract, primary neoplasms are more likely to be malignant than benign. Papillomas, leiomyomas, fibromas, neurofibromas, hemangiomas, rhabdomyomas, and myxomas are found infrequently. |
| Among primary malignant neoplasms of the lower urinary tract, transitional cell carcinomas are diagnosed most frequently in both species. Squamous cell carcinomas, adenocarcinomas, fibrosarcomas, leiomyosarcomas, rhabdomyosarcomas, hemangiosarcomas, and osteosarcomas also are found. 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. They are
highly invasive and metastasize frequently, most commonly to the regional lymph nodes and lungs. Ureteral and bladder neoplasms can cause chronic obstruction to urine flow with secondary hydronephrosis. Urethral tumors are more likely to cause acute obstructive uropathy. Intractable secondary bacterial urinary tract infections are commonly associated with neoplasms of the bladder and urethra. |
| Clinical Findings: |
| Hematuria, 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 uremia 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. |
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| Diagnosis: |
| History and clinical signs are highly suggestive of lower urinary tract disease in animals with tumors of the bladder or urethra. Urinalysis frequently reveals hematuria, and there may be evidence of secondary infection. Chronic, uncomplicated urinary tract infections must be differentiated from those associated with neoplasms. Neoplastic cells may be found in the sediment, particularly with transitional cell carcinomas. A cystourethrogram, retrograde urethrogram, or
ultrasonography is generally necessary to determine the location and extent of the tumor. Biopsy of the tumor is required for definitive diagnosis.
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| Treatment: |
| Excision of the tumor, 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. Chemotherapy with cisplatin or piroxicam may prolong the life of affected animals. |
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