Bladder cancer awareness month is May. Urinary tumors can occur in dogs and cats. Cancer in our pets is a scary thing. It is important to have good information to empower you to make better decisions for your pet.
What are bladder tumors?
Bladder and prostate tumors are uncommon in pets. Like most tumors in animals and people, we do not know why they occur. There have been a few studies which linked increased exposure to lawn herbicides and insecticides to bladder tumors in Scottish terriers. Eating more vegetables was also found to decrease the rate of bladder tumors in one study.
Tumors typically arise from the lining of the bladder or urethra, and can also involve the prostate in male dogs.
What will You See at Home with Your Pet?
The most common presenting complaints for pets with bladder tumors are increased frequency and urgency of urination, with or without blood in the urine. These signs are identical to the signs that dogs with urinary tract infections may show. It is common for the signs to temporarily or partially improve with antibiotics, but this does not signify that an infection or inflammation is the root of the problem, as bladder tumors can make dogs more susceptible to infection as a secondary problem. Some dogs with tumors of the prostate may have problems defecating as their primary complaint.
What Happens at the Vet Clinic with Your Pet?
When a pet comes in with signs of bloody urine or increased straining and urgency to urinate, a number of tests are performed. Initially, microscopic evaluation of a sample of urine with or without blood tests to look at overall health and organ function are performed. If there are any signs of infection, then antibiotics are started. A urine culture may also be recommended. A culture grows the bacteria in the urine. Once the type of bacteria is known, then the best antibiotic can be given. Many dogs with bladder infections (also called UTIs (Urinary Tract Infections) will improve quickly and the straining to urinate resolve. Dogs with tumors may have improvement at first, but then the signs quickly return in a few days to weeks.
Abdominal ultrasound can identify the mass in the urinary tract and evaluate for any signs of spread of disease such as enlarged lymph nodes. Most bladder tumors in dogs arise from the trigone, or the back part of the bladder where the urethra connects. If a tumor is suspected, X-rays of the lungs will often be obtained as well, to rule out distant tumor spread. Spread of cancer to other organs carries a worse prognosis and treatment options are different than for dogs who do not have spread. This is why it is important to do these tests when a tumor is found.
Several tests can be done to try to obtain a diagnosis. One test involves the guidance of ultrasound by inserting a catheter into the urethra and dislodging a small piece of abnormal tissue, which can be submitted for microscopic evaluation, or through a small flexible scope attached to a camera (cystoscopy) that can be passed into the bladder. Occasionally, increased bleeding may be noted after the biopsy procedure. We will achieve a diagnosis in approximately 80% of the biopsies that we take in this fashion. Sometimes, enough abnormal cells can be seen in the urine that we can feel reasonably confident about the diagnosis. The Cadet BRAF test is performed on a large urine sample and determines if there is a mutation which is associated with the tumor. This test can rule IN a tumor but a negative result does not rule OUT a tumor. The most common type of bladder or prostate tumor we see is called urothelial carcinoma.
What are the Treatment Options for Your Pet?
In those cases where the tumor occurs in a location where surgery is possible, surgery is the treatment of choice. When complete surgical removal can be performed, the average survival time with surgery alone is approximately 1 year with some dogs living much longer, but recurrence is very high within the first few months.
Unfortunately, surgery is almost never possible with most tumors due to the location and especially with prostate cancer, due to a high risk of permanent incontinence. Medical therapy is often the most useful therapy for these patients. One drug that is often used is the aspirin-like drug called piroxicam. Piroxicam is commonly used in people to treat arthritis. But it has been found to have some anti-tumor effects especially with urinary carcinoma. Piroxicam improves the signs of straining, bleeding, and urgency in approximately 75% of dogs, and approximately 20% of dogs will actually experience meaningful tumor shrinkage. Piroxicam alone results in an average survival time of approximately a few months, which is about twice as long as dogs that do not receive piroxicam. Piroxicam and chemotherapy combinations appear superior to either treatment alone. Many different chemotherapy drugs have been evaluated. The addition of the chemotherapy results in meaningful tumor shrinkage, and extends average survival times. Most pets tolerate chemotherapy very well, with only a small likelihood of developing worrisome side effects. Pets that respond to chemotherapy will remain on treatment as long as it is effective and tolerated. To make sure it is still effective, we recommend restaging with abdominal ultrasound and chest x-rays.
Radiation therapy is another option to treat the bladder mass. A CT scan will be needed for radiation planning. This treatment is generally once daily for three days. It can increase survival time when combined with chemotherapy. Side effects such as diarrhea and painful urination can occur following radiation that generally resolves in a few days to week. Late term side effects such as urethral, ureter, and colonic strictures can occur several months after treatment. A consultation with a radiation oncologist is recommended to go over this option in more detail.
What Will You See as the Tumor Grows?
Regardless of therapy, most bladder tumors will start to grow at some point. Several problems can develop as bladder tumors progress. These could include: (1) signs related to tumor spread to the lymph nodes, abdominal organs or lungs; (2) kidney failure as a result of blockage of the ureters (the tubes connecting the kidneys and bladder), or; (3) An inability to urinate due to blockage of the urethra. It is important to watch for changes in urination and report those signs to your veterinarian. It is an emergency if your pet is unable to urinate.
This is a lot of information and hard to digest when you have been told your beloved pet has a bladder/urinary cancer. It is important you get all the correct information, so you know what is best for you and your pet. Every pet and family is different and not all options work for everyone. Talk with your vet and a veterinary oncologist to get this needed knowledge. Veterinary oncologists have at least 4 extra years of advanced training and all they do is treat cancer. Pet Cancer Care Consulting is a service which partners boarded oncologists with your family veterinarian to give this information and help you determine the next best steps for you pet. This could be going to an oncologist’s clinic for IV chemotherapy, seeing a radiation oncologist, or treating with pill chemotherapy with your family vet. Look into Pet Cancer Care Consulting to see how we can help you.