Bladder tumors are uncommon in dogs and cats. Like most tumors in animals, we do not know why they occur. There is some evidence suggesting that exposure to herbicides may be a risk factor in Scottish Terriers. Transitional cell carcinomas typically arise from the lining of the bladder or urethra, and can also involve the prostate in male dogs.

The most common presenting complaints for animals with bladder tumors are pollakiuria, stranguria, and hematuria. Often, these signs are mistaken for a urinary tract infection. Dogs with transitional cell carcinoma may improve on antibiotics initially because secondary urinary tract infections are common with this disease. Dogs with recurrent urinary tract infections should have an abdominal ultrasound performed. This test is the best test to identify these tumors.

Following the identification of a bladder tumor, a biopsy is indicated to confirm  a diagnosis of transitional cell carcinoma and to rule out polyploidy cystitis or other types of neoplasia such as rhabdomyosarcoma. The easiest way to obtain a biopsy is via traumatic catheterization. A catheter is inserted into the urethra and using ultrasound guidance, pieces of the abnormal tissue are dislodged. Cystoscopy can also be used to obtain biopsies. The advantage of this procedure is that it allows us to visualize the tumor as well as the ureteral orifices. The disadvantage is that it requires general anesthesia and is far more expensive than traumatic catheterization. With both procedures, diagnostic samples are obtained 85 percent of the time. Ultrasound guided fine needle aspirates are controversial. Transitional cell carcinoma can seed the needle tract so it is generally not recommended. Rarely, the diagnosis can be made via urinalysis if enough abnormal transitional cells are seen in the absence of infection. The bladder tumor antigen test is not very useful for diagnosing this tumor as urinary tract infections and/or any inflammation of the bladder can cause false positives.

Transitional cell carcinoma frequently metastasizes to the medial iliac lymph nodes. These lymph nodes are evaluated during the patient's abdominal ultrasound. This tumor also can metastasize to the lungs so three view thoracic radiographs are indicated. Urogenital tumors also have a predilection for metastasizing to bone so if a dog with a bladder tumor is presented for orthopaedic pain, the painful bone should also be radiographed.

If the tumor occurs in the apex of the bladder, surgery is the treatment of choice. However, partial cystectomy is not curative. Median survival time is approximately one year. These tumors are extremely friable and seed the entire urogenital tract. There is also a theory called field carcinogenesis. The basic idea is that there is likely a carcinogen in the urine transforming the transitional cells and all of the cells in the bladder have had exposure to this carcinogen.

Unfortunately, most transitional cell carcinomas occur in the trigone making complete surgical removal impossible. Options for these patients are radiation therapy, chemotherapy, and palliative stenting. The best survival times are reported by combining curative intent radiation therapy and chemotherapy. Radiation therapy involves approximately 20 treatments given Monday through Friday. It is a labor-intensive treatment and there are significant side effects.

Chemotherapy alone can also be effective for the treatment of transitional cell carcinoma. Several chemotherapy drugs are used to treat this tumor including piroxicam, mitoxantrone, vinblastine, and metronomic chlorambucil. On piroxicam alone, approximately 75% of patients will have improvement of clinical signs. Median survival time is approximately 6 months. With the addition of mitoxantrone, median survival time improves to approximately 9 to 10 months. Dogs who do not respond to mitoxantrone may respond to vinblastine or metronomic chlorambucil.  

As these tumors progress, urethral obstruction can become a life threatening problem. This condition can be treated with stenting. Urethral stents are placed in a minimally invasive fashion using fluoroscopic guidance. The major complication of this procedure is urinary incontinence, which occurs in approximately 25 percent of patients. Unfortunately, there is no way to predict which patients will be incontinent following the procedure.

Another sequel is ureteral obstruction leading to hydronephrosis and ultimately renal failure. This condition can also be treated with stenting. If dogs have hydronephrosis and hydroureter (renal pelvis dilated greater than 5 mm) ureteral stents can also be placed in a minimally invasive fashion. Using ultrasound and fluoroscopy, the stent can be placed percutaneously. Alternatively, we can place the stent using cystoscopy.

Both ureteral and urethral stenting are palliative procedures. They do not prevent tumor progression and are best used in conjunction with chemotherapy or radiation therapy. Both of these procedures can be performed at VCA Alameda East.  

Originally from Connecticut, Dr. Anne Skope completed her B.A. in Philosophy from Colgate University (Hamilton, NY) in 1998. After veterinary school, she spent a year doing biomedical research at Harvard Medical School in Boston, MA. Dr. Skope attended veterinary school at the University of Pennsylvania and graduated in 2003. Upon graduation, she was selected for an internship at VCA West Los Angeles Animal Hospital. She then returned to Boston to do an oncology-dedicated internship at Angell Animal Medical Center.

After her year at Angell Animal Medical Center, Dr. Skope came to Colorado State University to complete a 3 year residency program in small animal oncology, as well a M.S. degree. Research during her residency focused on investigating a novel treatment strategy for canine lymphoma.

In her free time, Dr. Skope enjoys hiking with her Labrador Retriever, Fletcher, skiing and spending time with her family and friends.