|Bladder Cancer in Cats and Dogs
|What are bladder tumors?
Bladder is the organ that collects urine excreted by the kidneys prior to disposal by urination. The most common type of
bladder cancer is called transitional cell carcinoma (TCC), which arises from the epithelial cells that line the bladder.
However, other less frequently observed types of bladder exist such as squamous cell carcinoma, adenocarcinoma,
undifferentiated carcinoma, rhabdomyosarcoma, fibroma, and other mesenchymal tumors. In dogs, this tumor invades into
the deeper layers of the bladder wall including the muscle layers. As the tumor grows bigger, it can cause obstruction to
the flow of urine from the kidneys to the bladder or from the bladder to the outside of the body. TCC in dogs also has the
ability to spread to lymph nodes and to other organs in the body such as the lung or liver.
To review a comprehensive information prepared by the Purdue University School of Veterinary Medicine about canine
TCC, click here.
Source: www.animalhelp.com/images/articles/malecatreprosys3.jpg (cat)
How common are bladder tumors in cats and dogs?
Bladder cancer is not very common, It accounts for approximately 2% of all reported cancers in the dogs and rarely
reported in cats. The exact cause of TCC is usually not known but in general, canine TCC results from a combination of
several factors including genetic predisposition and environmental factors. A genetic predisposition is suspected because
TCC is more common in specific breeds of dogs, including Scottish Terriers (18 fold increased risk compared to other
breeds), Shetland Sheepdogs (4 fold increased risk), Beagles (4 fold increased risk), West Highland White Terriers (3 fold
increased risk), and Wire Hair Fox Terriers (3 fold increased risk). Environmental factors identified as risk factors in
previous studies have included pesticides, insecticides and "old generation" flea dips. One of the cause of TCC in humans
is smoking but the extent to which second hand smoke may contribute to TCC in dogs is not known at this time.
What are the symptoms of bladder tumors in cats and dogs?
The most frequent symptoms of TCC are blood in the urine, painful urination, frequent urination and/or straining to urinate.
These symptoms overlap with those common in urinary tract infection, therefore, these symptoms alone do not necessarily
mean that the pet has TCC. If the tumor has spread to other organs such as the bones or the lungs, the pets may show
lameness and a paraneoplastic syndrome called hypertrophic osteopathy.
How is the diagnosis made?
Bloody urine accompanied by difficulty to urinate could be caused by a variety of medical conditions other than cancer
such as bladder infection, bladder stones, or bladder inflammation. The veterinarian will, therefore, have to first conduct a
series of steps to rule out these common conditions. These tests include complete blood count (CBC), serum biochemistry
profile, urinalysis, urine culture, X-rays of the abdomen and chest, and bladder imaging (eg cystography or
cystosonography). Some of these conditions can also produce "masses" to be seen on radiographs or ultrasound, and
some can cause abnormal cells in the urine, which can be mistaken for TCC. Therefore, the definitive diagnosis of TCC will
require a tissue biopsy and subsequent examination of the cells under the microscope. This is important because the
treatment and prognosis depend entirely on exactly what is wrong with the bladder. A tissue biopsy can be obtained by
surgery, cystoscopy (insertion of a fiberoptic scope into the bladder and biopsy through the scope), or in some cases with
a urinary catheter.
What evaluation is needed for a pet with transitional cell carcinoma?
Once a diagnosis of TCC is made, it is important to determine the stage (extent) of the disease so that the oncologist can
determine the best way to treat the cancer, to gain some information about the pet's prognosis, and to establish a baseline
tumor measurement in order to determine if treatment is successful. The staging process typically looks at three factors:
the primary tumor, spread to lymph nodes, and spread to distant organs. Tumor staging for TCC includes chest X-rays to
look for lung metastasis, abdominal X-rays and ultrasound (or CT scan) to look for metastasis in the abdomen and to
assess any changes in the kidneys, and imaging of the bladder to determine the exact location and size of the tumor.
These tests are repeated during treatment to know if the treatment is being effective.
Does cancer cause pain in pets with cancer?
Pain is common in pets with cancer, with some tumors causing more pain than others. In addition to pain caused by the
actual tumors, pets will also experience pain associated with cancer treatments such as surgery, radiation therapy or
chemotherapy. Untreated pain decreases the pet's quality of life, and prolongs recovery from the illness, treatment or
injury. It is, therefore, essential that veterinary teams that are taking care of pets with cancer should also play a vital role in
educating pet owners about recognizing and managing pain in their pets. The best way to manage cancer pain in pets is to
prevent it, a term referred to as preemptive pain management. This strategy anticipates pain ahead of time and
administers pain medication before the pet actually experiences pain, thus ensuring the pet's maximum comfort.
To learn more about which tumors are likely to cause a lot of pain, how to recognize pain in pets with cancer and what
cancer pain management options are available for your pet, please visit the Cancer Pain Management section.
How important is nutritional support for pets with cancer?
Cancer cachexia (a term referring to progressive severe weight loss) is frequently observed in pets with cancer. Pets with
cancer lose weight partly because of lack of appetite and partly because of cancer-induced altered metabolism. Some of
the causes for decreased appetite are related to the cancer itself (for example, tumors may physically interfere with food
chewing, swallowing, and digestion process) and some may be related to the side effects of cancer treatment (for example,
some chemotherapy drugs cause nausea and vomiting, and radiation therapy can cause mouth inflammation).
Proper nutrition while undergoing cancer treatment is essential to maintain your pet's strength, improve survival times,
quality of life and maximize response to therapy. Adequate nutritional support was shown to decrease the duration of
hospitalization, reduce post-surgery complications and enhance the healing process. Additionally, pets with cancer need to
be fed diets specifically designed to provide maximum benefit and nutritional support for the patient. To learn more, please
visit the Cancer Nutrition section.
What are the treatment options for bladder cancer in cats and dogs?
Because most canine TCCs are invasive into the bladder wall and located in the neck of the bladder where several vital
structures are located, surgical removal is usually not possible. It has not yet been completely determined what benefit
would occur from removing part of the tumor in dogs in which the entire tumor cannot be removed. If surgery is not
possible, radiation therapy can be used to control the growth of TCC, however, its associated complications, including a
scarred, shrunken bladder, and irritation to surrounding organs, largely limit its clinical benefit. The majority of TCC cases
are treated with two types of approaches: traditional chemotherapy (eg cisplatin, carboplatin, adriamycin) and nonsteroidal
antiinflammatory drug (NSAID) called piroxicam.
The response to chemotherapy alone has been rather disappointing and oncologists at Purdue University Veterinary
School of Medicine became interested in piroxicam when unexpected remissions were noted in dogs in whom the drug was
used for pain relief. This has led to numerous studies of piroxicam in pets with cancer at Purdue. In 62 dogs with TCC
treated with piroxicam, the tumor went into complete remission in 2 dogs, decreased in size (by > 50%) in 9 dogs, remained
"stable" in size (<50% change) in 35 dogs, and increased in size (by > 50%) in 16 dogs. The median survival (195 days)
compared favorably to survival with chemotherapy in other studies. In an attempt to improve the response of TCC to
therapy, oncologists at Purdue University conducted a study comparing chemotherapy (cisplatin) alone to chemotherapy
plus piroxicam. In this study the combination of cisplatin and piroxicam was more effective against the cancer, but the
combination treatment caused a rise in the urea level in a blood test, indicating that the combined treatment affected
kidney function. Combining piroxicam with other chemotherapies has not been as successful. Currently, oncologists at
Purdue University are conducting a study of cisplatin chemotherapy combined with a new NSAID drug to evaluate if tumor
remission can occur with less toxicity. Recently, concerns have been published regarding a potentially small increase in
risk for heart attack and stroke in people receiving this new drug but because dogs do not develop disease in their blood
vessels like humans do, the drug is not expected to produce similar side effects.
What are the treatment associated risks?
Drugs like piroxicam have few side effects but in some dogs (less than 20%), piroxicam will irritate the stomach or intestine.
Therefore, if a dog on piroxicam has loss of appetite, vomiting, or dark tarry-looking stools, it is safest to stop the piroxicam
and consult the veterinarian before starting the medication again.
How do I find a qualified veterinary oncologist?
To locate a qualified veterinary oncologist in your area who can discuss with you appropriate cancer treatment plan for
your pet's cancer condition, please visit the "Locate a veterinary oncologist" section.
What is the prognosis for bladder cancer in cats and dogs?
Survival is affected by the growth rate of the tumor, the exact location of the tumor within the bladder, and whether the
tumor has spread to other organs or not. Unfortunately, most dogs with TCC will eventually succumb to the disease but
many will enjoy several months or longer with a good quality of life. The median survival in dogs treated with chemotherapy
(cisplatin or carboplatin) at Purdue University was 130 days. Median survival with piroxicam treatment in 62 dogs with TCC
was 195 days. The survival times in all of these studies, however, varied tremendously from dog to dog. Some dogs have
died after only a few days, while others have lived more than two years. Factors that have been identified in Purdue
University studies that negatively affect survival time include more extensive tumor within the bladder, spread of tumor
beyond the bladder, and involvement of the tumor in the prostate gland. Regarding metastasis of TCC in dogs,
approximately 20% of dogs with TCC have detectable metastasis at diagnosis, and 50% have metastasis at death. Longer
survival times have been reached when chemotherapy is combined with piroxicam, but the optimal combination treatment is
still being determined.
Are there any clinical trials for bladder cancer in cats and dogs?
There are clinical trials ongoing for dogs with bladder cancer, which are partially funded by the institutions. To learn more
about these trials, please visit the Canine Bladder Clinical Trials section.
Additionally, there are several clinical trials available for cats and dogs with any tumor type for which your pet may qualify.
To learn more these trials (which are partially or fully funded by the institutions), please visit the Dog Clinical Trials (any
tumor type) or Cat Clinical Trials (any tumor type) section.
To learn more about veterinary clinical trials in general, please visit the Pet Clinical Trials section.
Additional online resources about bladder cancer in pets
|PET CANCER CENTER
Comprehensive guide to cancer diagnosis and treatment in cats and dogs