Urinary Bladder Cancer in Cats
Dr. Jeffrey Philibert
Urinary bladder tumors are rare in cats, but of the possible cancers, transitional cell carcinoma is the most commonly diagnosed. This is a malignant cancer usually arising from the inside surface of the urinary bladder or urethra and less commonly from the muscular wall of the urinary tract. Blood in the urine
The cause of transitional cell carcinoma is unknown, but carcinogens, or cancer causing chemicals, that are excreted in the urine may cause the cells that line the bladder and urethra to become cancerous. Exposure to insecticide dips applied to kill fleas and ticks may increase the risk of developing this type of cancer. Similarly, exposure to sprays used to control mosquitoes in marshy or wetland areas also may increase risk.
Cyclophosphamide, a drug used to treat cancer and certain immune diseases, is metabolized to a carcinogenic chemical called acrolein, which is excreted in the urine. Exposure to cyclophosphamide may increase a pet's risk for development of urinary bladder cancer.
Female cats are affected more commonly than males and obesity also may predispose to development of this type of cancer.
Urinary bladder cancer is life-threatening. Left untreated, it can result in obstruction of the urinary tract and inability to urinate. This form of cancer can also metastasize, or spread to other parts of the body. At the time of diagnosis, transitional cell carcinoma is estimated to have spread in more than 50 percent of cats in which it is diagnosed. Survival of cats with this type of cancer is dependent on the location of the tumor in the bladder, extent of disease and whether it has metastasized, and what treatments are prescribed. Survival time can range from weeks to more than a year.
What to Watch For
Straining to urinate
Increased frequency of urination with passage of small amounts of urine
Straining while defecating
Signs of exercise intolerance
Difficulty breathing or coughing
In many cases, these signs can be present for many months before diagnosis. If your pet is showing any of these signs and does not seem to be getting better with treatment, additional tests should be done to rule out cancer as the cause.
Diagnostic tests are needed to recognize urinary bladder cancer and exclude other diseases. Tests may include:
Complete medical history and physical examination including rectal examination to palpate the urethra, bladder neck, male prostate gland and local lymph nodes
Plain X-rays of the abdomen to evaluate for masses and lymph node enlargement and of the chest to evaluate for metastasis
Complete blood cell count
Serum biochemistry tests to evaluate your pet's general health, other body systems, and to identify metabolic consequences of urinary obstruction
Urinalysis to evaluate for white cells, red cells, bacteria or tumor cells
Cytology examination of urine to evaluate for tumor cells
Abdominal ultrasound examination to evaluate the location and extent of the bladder tumor, the status of regional lymph nodes, and the presence of obstruction of the urinary tract
Contrast dye X-ray studies to evaluate the location and extent of the bladder tumor in the place of abdominal ultrasound examination
Urethrocystoscopy by passing a rigid or flexible scope into the urethra and bladder under anesthesia to identify the location and extent of the tumor. This procedure allows for biopsy of the tumor, but usually requires referral to a veterinary specialist.
A relatively new test called V-TBA has become available to screen for the presence of a bladder tumor marker in the urine of cats suspected to have transitional cell carcinoma.
Your veterinarian may refer you to a veterinary cancer specialist (oncologist) to discuss treatment options. Treatment for urinary bladder cancer may include one or more of the following:
Surgery for small masses confined to certain locations in the body of the urinary bladder. Unfortunately, many transitional cell carcinomas are found in parts of the bladder that are not amenable to surgery.
Cancer chemotherapy for some cats with transitional cell carcinoma
The non-steroidal anti-inflammatory drug piroxicam (Feldene®) has show some promise in symptomatic treatment of some cats with transitional cell carcinoma. In one study, tumors regressed in approximately 25 percent of treated cats, remained stable and did not grow in 50 percent of treated cats, and progressed in 25 percent of treated cats.
Home Care and Prevention
Evaluation for cancer of the urinary bladder is warranted if you have an older cat and notice blood in the urine, increased frequency of urination, and straining to urinate that either does not respond to routine treatment with antibiotics or that resolves only to return after stopping antibiotic treatment.
You should seek veterinary care immediately if you suspect that your pet is unable to urinate. Inability to urinate leads to severe metabolic complications called uremia within less than three days of complete urinary obstruction.
Watch your pet closely for changes in urinary habits after diagnosis has been made and treatment begun, because such changes may indicate additional tumor growth.
Avoid dipping your cat with flea and tick control products more than two times per year due to possible increased risk of developing bladder cancer. If you live in an area of the country where fleas and ticks are a year-round problem, talk to your veterinarian about alternative forms of flea and tick control.
Obesity may predispose your pet to this type of cancer. Regular exercise and diet control are recommended for the general health of your pet.