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Study to Evaluate Placement of Stents in Dogs with Bladder/Urethral/Prostate Tumors

February 17, 2012

February 17, 2012

Cancer affecting the bladder, urethra or prostate can result in partial or complete obstruction of the urethra and clinical signs such as blood in the urine and straining to urinate are commonly noted. The three major treatment options for these patients include surgery, chemotherapy and/or radiation therapy. While these treatments may alter the course of the primary tumor, they are not generally successful or recommended for the initial treatment of a patient with a complete urethral obstruction and subsequent retention of urine.

Urethral Stents
Historically, treatment of a dog with complete obstruction of the urethra included placement of a urethral catheter, serial removal of urine via the placement of a needle into the bladder or placement of a permanent tube from the urinary bladder to the skin. These options are often not practical and can result in significant morbidity. Recently, the use of urethral stents has developed as a novel and less invasive treatment option for affected patients. Urethral stents are placed in a minimally invasive manner and open the urethra by causing a permanent outward force over the obstructed area. Urethral stents have been successfully placed in many dogs with tumors causing obstruction and outcomes have been positive.
A study is currently being conducted at the UC Davis Veterinary Hospital by Dr. William Culp, Dr. Jodi Westropp and Dr. Carrie Palm to evaluate some of the effects of urethral stents. The goal of the study is to determine the pressures that exist within the bladder and urethra in dogs with tumors causing urethral obstruction both before and after the placement of a urethral stent. The pressures are determined in a minimally invasive manner via placement of a catheter within the bladder and urethra. 

Enrollment Requirements
The following are requirements that must be met for enrollment:
•Canine patients with confirmed neoplasia (cancer of the bladder, urethra or prostate) resulting in malignant urethral obstruction.
•The patient is deemed to be a good candidate for urethral stenting through the evaluation of clinical signs, cystourethroscopy and fluoroscopy.
•The patient can be evaluated at 3 weeks after the stent placement and urethral and bladder pressures are determined at that time.

Information for Referring Veterinarians
Diagnostics that will likely be performed prior to enrollment in the study include bloodwork (CBC and chemistry panel), urinalysis, urine culture and cystourethroscopy. An aspirate or biopsy of the tumor may also be performed during cystourethroscopy. If the dog is deemed a candidate for enrollment and the client consents, initial pressure measurements will be obtained immediately prior to stent placement (under the same anesthesia). A second pressure measurement will be performed 3 weeks after stent placement. All costs associated with the 2nd pressure measurement will be paid for by the study, as will the anesthesia for the stent placement. Please contact Dr. Culp (see below) with any questions.

Information for Clients
The urethral stent is placed solely as a means of relieving the obstruction of the urethra. It is often still recommended that you pursue treatment of the primary tumor (usually transitional cell carcinoma of the bladder/urethra or carcinoma of the prostate) through visits with our oncology service. Additionally, not all patients are candidates for urethral stenting at the time of initial diagnosis. The oncology service or Dr. Culp or Dr. Westropp can discuss the timing of urethral stent placement with you. Please see the following overview of compensation and study requirements:
•The study will pay for the anesthesia utilized during the stent placement.
•The study will cover all costs associated with the bladder and urethra pressure measurements.
•The study will cover all costs associated with the 3 week recheck.
•When enrolling in the study, you are committing to a recheck evaluation at the 3 week period with concurrent pressure measurements; if you feel that you will not be able to accommodate this visit, your dog will not be able to be considered for study enrollment.
•Clients must be willing to sign a consent form and comply with the study protocol.

Thank you for your interest in improving the quality of life for our canine patients affected by cancer.

For more information on this study, please contact:
Dr. William Culp, Surgical and Radiological Sciences,
Dr. Jodi Westropp, Veterinary Medicine and Epidemiology,

G. V. Ling Urinary Stone Analysis Laboratory