Page 1371 - Clinical Small Animal Internal Medicine

146 Tumors of the Urinary Tract 1309

cystadenocarcinoma, and uterine tumors. This syndrome
Box 146.1 TNM clinical staging system for canine
VetBooks.ir bladder cancer is similar to Birt–Hogg–Dubé syndrome in humans.
Pulmonary metastases have been detected radio-
T – primary tumor
at the time of diagnosis. At death, metastases were
Tis Carcinoma in situ graphically in 16–34% of dogs with primary renal tumors
T0 No evidence of a primary tumor detected in 69% of dogs with carcinomas, 88% of dogs
T1 Superficial papillary tumor with sarcomas, and 75% of dogs with nephroblastomas.
T2 Tumor invading the bladder wall, with induration
T3 Tumor invading neighboring organs (prostate, Epidemiology
uterus, vagina, and pelvic canal)
N – Regional lymph node (internal and external iliac The etiology of renal tumors in dogs and cats is unknown.
lymph node) The previously mentioned syndrome in German
N0 No regional lymph node involvement shepherd dogs is the result of a dominantly inherited
N1 Regional lymph node involved missense mutation of a tumor suppressor gene. In cats,
N2 Regional lymph node and juxtaregional lymph feline leukemia virus (FeLV) is strongly associated with
node involved development of renal lymphoma.
M – Distant metastases
M0 No evidence of metastasis Signalment
M1 Distant metastases present Most renal tumors occur in older dogs (mean age 8 years)
but nephroblastoma may occur at any age. The male to
defined. The reported median survival of cats treated female ratio of dogs with epithelial renal tumors has
with surgery and adjunctive therapy (i.e., chemotherapy been reported to be 1.2:1. In cats, the median age at
or NSAIDs) was 269 days. diagnosis was 11 years with a similar number of male and
female cats.

Urethral Tumors History and Clinical Signs

Most tumors affecting the urethra are malignant. Clinical signs associated with renal tumors are not spe-
Transitional cell carcinoma and squamous cell carcinoma cific. Presenting complaints may include weight loss,
are the most commonly reported tumor types. Smooth polyuria, lethargy, hematuria, abdominal pain or signs
muscle tumors (e.g., leiomyosarcoma) have been reported suggestive of renal failure (vomiting, anorexia). Physical
less frequently. Granulomatous urethritis, a benign examination may reveal a midabdominal mass and
condition of the urethra, must be differentiated from occasionally bilateral renal enlargement.
malignant tumors due to the different treatment
approaches and prognosis. Treatment recommendations Diagnosis
and response rates for urethral tumors are similar to
those of the bladder. Clinicopathologic findings include mild anemia alone or
accompanied with marked neutrophilia, or abnormalities
consistent with renal azotemia. Paraneoplastic syndromes
Renal Tumors such as polycythemia, neutrophilia, and hypertrophic
osteopathy have been reported.
Ultrasonography is highly sensitive for the diagnosis of
Etiology/Pathophysiology
renal neoplasia. Tissue samples can be obtained by
Primary renal tumors are uncommon in dogs and cats. The ultrasound‐guided percutaneous biopsy or at the time of
majority of these tumors are malignant and more than half surgery.
are epithelial in origin. In cats, lymphoma is the most com-
mon renal tumor and can affect both kidneys. In a report of
54 dogs with renal tumors, the most common was renal Therapy and Prognosis
cell carcinoma. Other tumors that can occur in the kidney Nephrectomy is the treatment of choice for dogs with
include TCC, nephroblastoma, hemangiosarcoma, other unilateral renal tumors without evidence of azotemia
sarcomas, and lymphomas. An unusual syndrome in or distant metastasis. Excretory urography, computed
female German shepherd dogs consists of slow‐growing tomography (CT), and evaluation of glomerular filtra-
dermal fibrosis and fibromas, concomitant renal tion rate (GFR) via scintigraphy may also be useful,