Bladder Cancer In Cats

A noticeable increase in the number of trips your cat makes to the litter box can be alarming. If you are concerned that bladder cancer is a possible cause, it will be helpful to learn as much as you can about the disease. Fortunately, bladder cancer in cats is very rare. It typically strikes cats aged 10 and up, and can occur in both males and females. Feline bladder cancer tends to be aggressive and can spread to the lymph nodes, the liver or the lungs. It also can spread locally, up into the ureters, which carry urine from the kidney to the bladder. That can cause kidney issues. This cancer also can spread into the urethra, which is the duct or tube leading from the bladder through which urine exits the body.

Bladder cancer treatment can provide a better quality of life for six months or so — and hopefully longer — but there is typically no cure. It’s important to know, however, that increased frequency of urination does not mean your cat has bladder cancer. Other issues can be prompting the increase in litter box visits. There are also other symptoms to look for that merit a visit to your veterinarian for a diagnosis. Notably, even if a mass is found in the bladder or urinary tract, it could be a benign growth, such as an adenoma or a polyp.

Types of Bladder Tumors

Tumors typically are categorized based on the location of origin:

  • The most common type of malignant bladder tumor in cats is a transitional cell carcinoma, which develops in the bladder lining.
  • Leiomyosarcomas stem from the smooth muscle tissue in the bladder wall.
  • Rhabdomyoma tumors form in the skeletal muscle.
  • Squamous cell carcinomas can also form in the bladder lining but are rare.
  • There are other types of carcinomas, as well.
photo of beautiful multi-colored cat

photo of beautiful multi-colored cat

Symptoms of Bladder Cancer in Cats

Urinating more frequently is one of the signs that a cat might have bladder cancer, but the urine itself can present symptoms, too. Things to look for include a smaller stream than usual, blood in the urine or a bad odor that is worse than usual. A stricken cat also may appear to be straining to urinate. If he or she is unable to urinate at all, that is considered an emergency. If this is the case, your cat should be taken to the nearest veterinary clinic.  If the bladder mass is large or if the cancer metastasizes to the regional lymph nodes, a cat also may strain to defecate and there may be a change in his or her stool shape. Weight loss and lethargy are additional signs that would merit a trip to the vet to determine the cause.

Workup for Bladder Cancer in Cats

Some of the symptoms of bladder cancer in cats are also associated with other conditions, such as a bladder infection or the presence of bladder stones. Excessive urination coupled with excessive water consumption can be signs of diabetes. To accurately diagnose what is causing a cat’s symptoms, a veterinarian will conduct a series of tests or procedures.

  • A urine culture and sensitivity test will determine the health of the urine and whether there’s an infection.
  • A complete blood count (CBC) and a blood chemistry profile provide information about a cat’s overall condition, which will help dictate the treatment course.
  • Abdominal X-rays and/or an abdominal ultrasound may be ordered to get a view of the bladder- and a view of the tumor, its size and precise location within the bladder lumen.
  • Three-view chest X-rays are used to determine whether cancer has spread to the lungs.
  • A fine needle aspiration may be used to collect a sample of the tumor cells. Samples are then sent to a lab to be analyzed by a veterinary pathologist, who can determine whether cancer is present.
  • A biopsy of the mass (a sample of the tumor tissue) may be done which would also be sent to a veterinary pathologist for a diagnosis and to determine how aggressive it is.

Treatment and Prognosis

The best treatment course for bladder cancer in cats depends on where in the bladder the cancer is located.


If a tumor is in the region of the apex of the bladder (the area toward the front of the body), surgical removal can result in a good response. The goal is to get wide, clean margins, meaning a significant portion of the outer edges of the removed tissue are cancer-free — an indication that the surgeon likely got all of the cancer out. However, with transitional cell carcinoma in cats, the cancer  is frequently in the trigone – the area of the bladder which is toward the tail. The trigone region is at the opening where urine passes from the bladder into the urethra. Surgery cannot successfully be performed in that area.


The use of radiation to treat a bladder tumor in cats is uncommon. Radiation entails directing high-energy rays at tumors while trying to minimize any damage to the surrounding tissues. Of the two primary types of radiation — conventionally fractionated radiation therapy (CFRT) and Stereotactic Radiation (SRS) — SRS is more advanced. It uses higher doses of radiation and precision targeting. It typically requires just one to three treatments, whereas CFRT requires 15 to 21. Since radiation requires that cats be anesthetized, the reduced number of anesthetic events using SRS can be advantageous.


Chemotherapy and non-steroidal anti-inflammatory drugs (NSAIDs) are more commonly recommended for treatment of feline bladder cancer, at times in addition to radiation or surgery. Chemo might be given intravenously or orally. If NSAIDs are prescribed, it is important to periodically have your feline’s kidney function assessed with a blood test and a urinalysis as these drugs can have side effects on the kidneys.

Ureteral Stents

While a ureteral stent isn’t a treatment for the actual cancer, it might be recommended if a bladder tumor is hindering a cat’s ability to urinate. However, an indwelling stent makes the cat more susceptible to urinary tract infections — plus, a tumor can grow over the stent and create a blockage.

Forgoing Treatment

Left untreated, a transitional cell carcinoma in cats will continue to grow. It will become more difficult for a cat to urinate. As the clinical signs progress and especially if your cat is trying to void though not producing any urine in the litter box, then it’s time for another veterinary exam.

PetCure Oncology Treats Bladder Cancer in Cats

If your cat has been diagnosed with bladder cancer, or you suspect he or she has developed cancer of any type, PetCure Oncology is here for you. While we specialize in SRS radiation therapy, we offer a full range of treatment options. Even more important, we pair our expertise with compassion. Our mission is to give your cat the best quality of life possible while extending your time together. For more information about our treatment options, find a location near you and contact us today.

The contents of this article were provided in part by Dr. Renee Alsarraf, DVM, DACVIM (Oncology), a board-certified veterinary medical oncologist and member of PetCure Radiation Oncology Specialists (PROS).

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