Page 1369 - Clinical Small Animal Internal Medicine

1307

VetBooks.ir

146

Tumors of the Urinary Tract
Pedro A. Boria, DVM, MS, DACVIM (Oncology)

Blue Pearl Veterinary Partners, Northfield, IL, USA

Tumors of the Urinary Bladder Signalment
Affected dogs and cats are usually older, with an average
Etiology/Pathophysiology age of 11 years and 13 years respectively. The most

Tumors of the urinary bladder are uncommon in dogs commonly affected breeds include West Highland
and rare in cats. Transitional cell carcinoma (TCC) is the white terriers, beagles, dachshunds, Shetland sheepdogs,
most common primary tumor of the urinary bladder in and Scottish terriers which have an 18‐fold risk of
both species. Other tumors reported include squamous developing TCC.
cell carcinoma, leiomyosarcoma, leiomyoma, undif-
ferentiated carcinoma, lymphoma, hemangiosarcoma, History and Clinical Signs
rhabdomyosarcoma, fibroma, and other mesenchymal
tumors. The most common clinical signs associated with TCC are
Transitional cell carcinoma is most often located in the stranguria, pollakiuria, hematuria, dysuria, and urinary
trigone region of the bladder in dogs and at the apex in incontinence. Urinary tract signs may present for weeks
cats. Mass lesions and thickening of the bladder wall can to months prior to diagnosis. Temporary relief of these
lead to partial or complete urinary tract obstruction. signs may be associated with the use of antibiotics.
Urethral and prostatic involvement has been reported In more severe cases, abdominal palpation may reveal a
in 56% and 29% of cases respectively. At the time of palpable caudal abdominal mass. Rectal examination
diagnosis, lymph node involvement is reported in 16% of abnormalities include urethral thickening or sublumbar
cases, with 14% demonstrating spread to distant sites. lymphadenopathy. TCC can also metastasize to the ingui-
The overall metastatic rate is 50%. nal lymph nodes, so palpation of the inguinal fat pads
may reveal firm masses. Other lower urinary tract condi-
tions resembling bladder TCC include other types of neo-
Epidemiology plasia, cystitis, polypoid cystitis, polyps, granulomatous

The overall incidence of bladder tumors is 2% of all cystitis/urethritis, and cystic calculi. Rarely, dogs have
reported malignancies in the dog. In cats, bladder cancer shifting leg lameness or warm, swollen, and painful limbs
is rarely reported. Risk factors associated with the devel- due to paraneoplastic hypertrophic osteopathy.
opment of TCC include exposure to older‐generation
topical flea and tick control products (i.e., flea and tick Diagnosis
dips), lawn herbicides and pesticides, obesity, female sex,
and a strong breed‐associated risk. The female:male Diagnostic evaluation of a patient with suspected TCC
ratio of dogs with TCC has been reported to range from should include deep abdominal palpation and rectal
1.71:1 to 1.95:1. The risk is higher in neutered dogs than evaluation. Rectal examination may reveal thickening
in intact dogs of both sexes. New‐generation spot‐on of the urethra and enlargement of internal lymph nodes.
flea control products do not appear to be associated The complete blood count and serum biochemical panel
with TCC. may reveal signs of renal involvement. Urine sediment

Clinical Small Animal Internal Medicine Volume II, First Edition. Edited by David S. Bruyette.
© 2020 John Wiley & Sons, Inc. Published 2020 by John Wiley & Sons, Inc.
Companion website: www.wiley.com/go/bruyette/clinical