Bladder cancer in cats is very uncommon. Because of this, we’re still learning a lot about feline bladder cancer, and a lot of what we do know is extrapolated from the findings about bladder cancer in dogs and people. In cats who do develop cancer of their urinary tract, the bladder is the second most common site, with lymphoma of the kidneys (renal lymphoma) being the most common urinary tract cancer in cats.

Even though bladder cancer in cats is rare, you don’t have to face this diagnosis on your own. Here, we’ll explain the causes, symptoms, and treatment options you can expect if your feline family member is diagnosed with bladder cancer.

What Is Bladder Cancer?

Our pets can develop benign polyps in the bladder, and they can develop tumors in other parts of the urinary tract, such as the kidneys, ureters (tubes from kidneys to bladder), and urethra (tube from bladder to outside of body). When we refer to bladder cancer, we specifically mean malignant tumors of the bladder.

In both cats and dogs, the most common cancer of the urinary bladder is called transitional cell carcinoma (TCC). This tumor arises from the cells that line the bladder and part of the urethra. While this tumor is almost always found in the lower neck of the bladder in dogs, the site of a bladder tumor in cats is more variable. This means that we can’t assume a tumor isn’t a TCC just because it’s located somewhere else in the bladder.

Other types of cancer can affect the urinary bladder, such as rhabdomyosarcoma or lymphoma. While we’ll mainly focus on TCC in cats, other cancers of the bladder have similar signs and similar treatment methods (surgery vs chemotherapy vs NSAIDs).

Stages of Bladder Cancer in Cats

When a cat is diagnosed with bladder cancer, the veterinarian will want to perform staging. When staging, they will measure the primary tumor, determine if the cancer is in nearby lymph nodes, and check for spread (metastasis) to other organs. Additional areas that transitional cell carcinoma is known to spread to include the lungs, lymph nodes, abdominal wall, kidneys, pancreas, and liver, among others.

TCC in cats doesn’t currently have its own validated staging system. There is a form of staging from the World Health Organization called the TNM staging system, focused on the primary tumor (T), lymph nodes (N), and distant metastases (M). If desired, this can be used to set a specific stage for the tumor.

Staging usually involves imaging, such as X-rays of the abdomen and chest, abdominal ultrasound, and potentially a CT scan. Accessible lymph nodes may be aspirated with a needle to collect cells to study for evidence of spread, though aspiration of lymph nodes in the abdomen is not recommended when TCC is suspected.

It’s not currently known what percentage of cats have metastatic disease when they’re first diagnosed, though some estimates state approximately 20 percent of cats already have spread. 

Causes of Cat Bladder Cancer

The cause of bladder cancer in cats is not fully understood. Utilizing what we know about bladder cancer in dogs and humans, some of the potential contributing factors could include:

• Carcinogens excreted in the urine that cause changes to the cells in the bladder or urethra
• Exposure to older formulas of insecticides and pesticides for flea and ticks
• Use of a chemotherapy drug called cyclophosphamide
• Genetic predisposition
• Obesity
• Older age (median age at time of diagnosis is 15 years)

Symptoms of Bladder Cancer in Cats

The symptoms of bladder cancer in cats often mimic other more common conditions, such as a urinary tract infection, feline lower urinary tract disease (FLUTD), or bladder stones. It’s important not to immediately assume your cat has cancer if you note these signs, but if their clinical signs are not resolving despite treatment for infection and inflammation, bladder cancer is a potential diagnosis.

Symptoms include:

• Straining to urinate
• Blood in urine
• Frequent urination with small amounts of urine produced
• Straining while defecating
• Difficulty breathing and coughing
• Unkempt appearance
• Overgrooming of genitals or belly
• Urinating outside the litterbox
• Vocalizing, especially in the litterbox
• Abdominal pain
• Vomiting
• Loss of appetite
• Lethargy
• Inability to urinate

The worst-case scenario is that the bladder tumor obstructs the urethra or a ureter. If the urethra is obstructed, your pet will be unable to urinate. This puts them at risk for bladder rupture and kidney failure. If the ureter is blocked, urine will be unable to flow from the kidney to the bladder, which would cause the kidney to enlarge and fail.

If your cat is vocalizing in the litter box but producing minimal to no urine, appears to have an enlarged abdomen, begins acting lethargic, loses their appetite, or is vomiting, this warrants a trip to an emergency veterinarian. Keep in mind that even with these symptoms, your cat is more likely to have a urinary blockage due to FLUTD than they are to have bladder cancer.

Diagnosing Bladder Cancer in Cats

Physical Exam

To diagnose bladder cancer in a cat, your veterinarian will start with a physical examination. They’ll want to perform testing to rule out the most common causes of urinary abnormalities. This could include a urinalysis with culture, blood work, abdominal radiographs, and abdominal ultrasound. If your pet appears to be blocked due to FLUTD (more common in males), your veterinarian is likely to attempt passing a urinary catheter to relieve obstruction.

If your pet has evidence of a urinary tract infection but no bladder stones, your veterinarian will typically start by treating the infection. If the signs do not improve or promptly recur, then bladder cancer should be considered as a rule-out.

Again, FLUTD in cats causes a lot of the same symptoms as both infection and a bladder tumor, but it’s more common than either of these conditions. If your veterinarian doesn’t find evidence of an infection but there is blood in the urine, your pet is much more likely to have FLUTD than they are to have bladder cancer, and they may recommend changing to a prescription urinary diet and reducing stressors in your cat’s environment.

Ultrasound

An ultrasound would be recommended to rule out the presence of a tumor or stones that were not detected on X-ray. Some veterinarians may do a special contrast study where a contrast dye that can be visualized on X-ray is injected into the bladder.

Biopsy

In cats, the most common way to get a biopsy of the tumor is through abdominal surgery. This is because they have a very small urethra, which may make cystoscopy (passing a camera through the urethra into the bladder) or the use of a catheter to collect a sample nearly impossible.

If your veterinarian sees a tumor on ultrasound, it may be tempting for them to stick a needle into the tumor to aspirate a few cells rather than doing surgery to collect a sample. For suspected transitional cell carcinomas, this isn’t recommended. TCC is known to travel along needle tracks, which may cause the tumor to “seed” to other areas of the body. This is a well-known occurrence in dogs, and there are reports of cats having their body wall affected via this presumed method as well.

Treatment for Cat Bladder Cancer

When we think of treatment for bladder cancer in cats, we typically focus on surgery, the use of non-steroidal anti-inflammatory drugs (NSAIDs), and chemotherapy.

Surgery

Surgery can be done if the tumor is small and confined to the body of the bladder. The ureters and urethra connect to the bladder in the neck area, often making surgery impossible if the tumor is in the neck of the bladder. Although most TCCs still recur after tumor removal, surgery currently has the most potential to extend life out of any known treatment.

Non-Steroidal Anti-Inflammatory Drugs

The use of NSAIDs has been shown to prolong survival in cats with TCC. Reportedly, the use of oral piroxicam can increase survival up to 6 months. Treatment can be complicated by pre-existing conditions, especially chronic kidney disease in older cats, which may limit NSAIDs as an option for your pet.  

Chemotherapy

Multiple chemotherapy protocols exist and will typically require your cat see the oncologist for a treatment every couple of weeks for a set number of treatments. With chemotherapy, you can expect your pet to receive multiple rechecks of blood work to ensure their body is tolerating the treatment. Chemotherapy medications result in decreased white blood cell counts, which can affect your pet’s ability to fight infection, so your veterinarian will want to ensure the white blood cell counts are not falling too low before giving their next chemotherapy dose.

Importantly, chemotherapy in pets is aimed at improving quality of life for as long as possible rather than radically pursuing a cure. Because of this, our pets typically tolerate chemotherapy much better than humans. You should report any side effects to your veterinarian so that they can ensure your cat remains comfortable throughout the process. 

Radiation

Your veterinarian may recommend radiation therapy. While this can be a good option for some pets, radiation therapy requires travel to a location that performs the procedure – often a university with a veterinary medicine program – and anesthesia each time the procedure is performed. For some pet parents, it is cost-prohibitive due to the time, money, and travel required.

Radical Surgery

Radical surgeries, such as removal of the entire bladder, can theoretically be performed. With this surgery, the bladder is removed, and the ureters are attached to either the colon or vagina. Because there is no longer a bladder to store urine, the cat becomes incontinent. This altered anatomy also significantly increases the risk of infection. These pets will frequently require long-term antibiotics and frequent blood monitoring to ensure their kidneys are functioning well. Because the ureters are such small tubes, it’s not uncommon for them to become blocked by scarring, which would ultimately result in kidney failure. This surgery isn’t recommended by most veterinarians.

Stenting

The role of stenting isn’t well known but may have a place in the management of TCC in cats. In a 2020 study, 11.9 percent of cats with bladder cancer had involvement of their urethra, 11.9 percent had evidence of obstruction of a ureter, and 5.1 percent had evidence of both urethral and ureteral involvement. 

Stents in these areas could allow urine to continue passing through, preventing obstruction. The placement of stents is a highly specialized procedure, so travel would likely be required if you are able to find a veterinarian experienced in stent placement.

Home Care 

When your cat has a bladder tumor, they have a higher chance of developing a bladder infection. Your pet will require frequent monitoring of their urine to ensure they are not developing a UTI. If this occurs, your pet will need antibiotics to treat the infection.

When your pet is at home, ensure they have easy access to food, water, and litter boxes. Your pet may have increased urgency to urinate, so you can help prevent accidents by having multiple litter boxes in easily accessed locations. 

Prognosis for Cats with Bladder Cancer

Survival times for cats with bladder cancer are not as well defined as they are in dogs, but one study involving 20 cats with TCC found a median survival time of 261 days. This included cats who received no treatment, as well as cats who received a variety of treatment protocols. A 2020 study found a median survival time of 155 days.

Untreated, the estimate for survival is 1-3 months. Medical management (NSAIDS and/or chemotherapy) has an estimated survival time of 5-6 months. If tumor location allows for surgery to be performed, cats who receive both surgery and medical management have an estimated survival time of 9-10 months.

End stage bladder cancer in cats usually involves obstruction of either the urethra or a ureter, preventing the flow of urine from kidney to bladder to outside of the body. This results in kidney failure. At this point, many pet parents elect to help their feline family member pass on peacefully via humane euthanasia. 

Cost to Treat Bladder Cancer in Cats

The cost to treat feline bladder cancer depends on the selected treatment method, which can range from around $2,000 up to $10,000. More conservative management would include imaging to confirm the presence of a tumor, blood work and urinalysis, and the use of NSAIDs. In this scenario, you would be keeping your pet comfortable and then electing for euthanasia when quality of life becomes a concern.

Once you add in chemotherapy, the cost will start to increase. Each treatment with chemotherapy costs several hundred dollars, and lab work will need to be rechecked prior to each treatment.

If surgery is an option for your pet, you can expect this to add several thousand dollars to the total cost, particularly if the procedure is performed by a specialist. For a cat to receive surgery, NSAIDs, and chemotherapy, you are looking at the higher end of the estimate.

How to Prevent Bladder Cancer in Cats

Because we are still learning a lot about bladder cancer in cats, we don’t currently know how to prevent the disease. While we cannot guarantee that it will prevent TCC, a healthy lifestyle is always recommended. Keep your cat at a healthy weight, feed a healthy diet, and ensure they always have access to clean, fresh water.