Urinary bladder cancer accounts for approximately 2% of all canine cancers. In
cats, cancer of the bladder is very rare. Invasive
transitional cell carcinoma (TCC) is the most common
type of cancer in the canine bladder. This type of
cancer is most often seen in older female dogs, with
breeds such as Scottish Terriers and Shetland Sheepdogs
topping the list. TCC invades the epithelial lining of
the bladder as well as the bladder muscles. This cancer
often metastasizes to other parts of the body, and is
therefore considered to be quite aggressive.
Approximately 50% of the time, the cancer spreads to
other parts of the body, including lymph nodes, lungs,
liver, and even bones. Signs of TCC can include blood
in the urine, straining to urinate, weight loss, and
possibly lameness if the cancer has spread to the bone.
cause of bladder cancer is likely multifactorial. An
association between herbicide exposure and TCC in dogs
was documented in a study of 166 Scottish terriers.
Associations have also been made between the development
of TCC and the use of topical flea products and tick
dips. Newer spot-on types of flea products appear to be
How is the diagnosis made?
If your pet is exhibiting the
pre-mentioned signs, your veterinarian may at first
suspect a urinary tract infection and even diagnose and
treat one. However, when signs persist through
appropriate antibiotic therapy, further diagnostic tests
are required. The most useful preliminary test to
identify a bladder tumor is an ultrasound. Contrast
cystograms are often used, which are radiographs taken
after a radiopaque dye has been put into the bladder.
These radiographs will show a “filling defect” in the
bladder or a thickened uneven border around the
bladder. There is also a test called the Bladder Tumor
Antigen Test (BTA) which looks for tumor proteins in the
urine. This test, although sensitive, is not highly
specific, and one should keep in mind that the only way
to definitively diagnose a bladder tumor is to perform a
biopsy. A biopsy can be done surgically, endoscopically
through the urethra, or sometimes even via a urinary
catheter. In the case of TCC, surgery is rarely
curative, so attempts to make the diagnosis in less
invasive ways are usually attempted first. Urine
samples may show abnormal cells, but these can be
difficult to interpret, especially if infection or
inflammation is present.
Ultrasound of a bladder showing diffuse disease along
the bladder wall.
one of the tumor types that can easily “seed” itself in
other locations. For this reason, collecting urine
through cystocentesis (a needle into the bladder) should
not be done to avoid the risk of seeding the tumor cells
in the abdomen or skin in the area. Surgery is usually
not possible because of the location that these tumors
typically occur. They tend to be found in the “trigone”
area of the bladder, which is where the urethra exits
the bladder and the ureters (from the kidneys) enter the
bladder. In addition, these tumors often are multifocal
within the bladder. In a series of 67 dogs with TCC
that underwent surgery, complete tumor-free margins were
only obtained in 2 dogs. Of the 2 dogs, one had a
relapse in the bladder 8 months later and the other
developed metastatic disease.
cell carcinoma cells. Multinucleated neoplastic
transitional epithelial cell (red arrow).
Athens Diagnostic Lab, University of Georgia.
Are other tests necessary?
staging (determining if any spread of cancer has
occurred) is required. Testing includes thoracic
radiographs (chest x-rays) to rule out the spread of
cancer to the lungs, lymph node aspirate/biopsy if any
lymph nodes are noted to be enlarged, CBC, chemistry
panel, and free-catch urinalysis to determine general
health, and ultrasound of the bladder and entire abdomen
(looking for enlarged lymph nodes or any effects the
tumor may be having on the ureters and kidneys).
Treatment of TCC: Surgery is not generally considered unless the visible
tumor is in a location that suggests a tumor type other
than TCC. With TCC, the most common form of therapy
used is a combination of chemotherapy (Mitoxantrone) and
a non-steroidal inflammatory agent (COX-2 inhibitor)
called piroxicam (FeldeneŽ). Piroxicam provides strong
analgesia and also acts indirectly on the tumor through
it’s COX-2 inhibition properties. Piroxicam alone can
improve the survival the time of a patients with bladder
cancer up to approximately 6 months. When combined with
Mitoxantrone chemotherapy, median survival time is
generally one year. Many patients can survive much
How is treatment administered? Chemotherapy is administered through an intravenous
catheter. Blood work is first performed to be certain
that the patient has adequate white blood cells and
platelets before administration of chemotherapy. Seven
to ten days after treatment a monitoring CBC is
required. Treatments are administered at 21 day
intervals and typically 5-6 treatments are performed.
Length of treatment depends on the response (ultrasound
is used to measure tumor response) and how the patient
is tolerating the chemotherapy. Piroxicam is an oral
medication given at home daily to every other day. If
chemotherapy and piroxicam are not effective, radiation
therapy can be considered.
cases where the ureters become obstructed and start to
damage the kidneys, special procedures can be utilized
to place a “stent” to re-establish the opening of the
ureter into the bladder. These procedures are
considered palliative and can improve the patient’s
quality of life. In a recently published study
Am Vet Med Assoc 2006 ; 226-234)
with malignant urethral obstructions underwent stenting
procedures and in 7 of the 12 dogs evaluated, the
outcome was good to excellent.
What supportive care is recommended? Patients with TCC are at higher risk for urinary tract
infections. Sometimes it is difficult to diagnose an
infection because one of the indicators of a non-cancer
patient with a urinary tract infection can be blood in
the urine. In the case of the bladder tumor patient,
blood in the urine is not necessarily an indicator of
infection. Cystocentesis to obtain a sterile urine
sample is contraindicated due to risk of tumor seeding,
therefore we often have to rely on a free catch sample.
Interpretation of free catch samples can be difficult
due to bacterial contamination. However, if patients
appear to be straining more or develop an odor to the
urine, they should be treated for infection.
may benefit from supplementation of cranberry, which is
believed to reduce the incidence of urinary tract
infection. In a study in humans (Yale University),
cranberry products inhibited the adherence of bacteria
to bladder and vaginal epithelial cells. Therefore,
there is scientific evidence to support these
supplements as a means to decrease infection rates.
Specific products and dosages can be discussed with our