Transitional Cell Carcinoma of the Urinary Tract in Dogs

Certain breeds are more often affected by transitional cell carcinoma, such as Wirehaired Fox Terriers, West Highland White Terriers, Scottish Terriers, Beagles, Shetland Sheepdogs, and Airedale Terriers. The most common place that transitional cell carcinoma originates is the area that the urinary tract system is the most complex, where the ureters and urethra meet the bladder. This is why one of the most frequently seen symptoms are difficulty urinating. In males, this condition commonly spreads to the prostate. In cases when the cancer spreads, your dog has a smaller chance of successful recovery.

Transitional cell carcinoma of the urinary tract is an invasive and rapidly spreading cancer that is common in dogs. In fact, transitional cell carcinoma is the most common bladder cancer in dogs. This kind of cancer starts in the epithelium (similar to many others), which is one of four tissues that make up a dog’s body along with muscle, nerves, and connective tissues. Transitional epithelium is part of what makes up the lining of the urinary tract system (bladder, urethra, ureters, kidney, prostate, and vagina), which can be primary or secondary. Primary transitional cell carcinoma is cancer that starts out in the urinary tract and secondary transitional cell carcinoma is cancer that spreads from somewhere else in the body.

Straining to urinate is the number one most often seen symptoms in transitional cell carcinoma. Other symptoms include:

• Excessive urination
• Urinary incontinence (inability to control urination)
• Bloody urine
• Licking of the penis or vulva
• Appetite loss
• Inflammation of the penis or vulva
• Vomiting
• Painful abdomen
• Hiding
• Exercise intolerance
• Difficulty sitting and walking
• Walking back and forth
• Constipation
• Anorexia
• Breathing difficulties
• Seizures
• Uncontrollable diarrhea and vomiting
• Sudden collapse
• Profuse bleeding from anywhere
• Whining or crying

 Types

• Primary transitional cell carcinoma is cancer that starts in your dog’s urinary tract system
• Secondary transitional cell carcinoma is cancer that started somewhere else in your dog’s body

Dogs that have transitional cell carcinoma have a thicker urinary bladder wall than other dogs, and there are almost always (98.9%) papillary lesions visible. Other causes are:

• Breed predisposition - Scottish Terriers (most commonly affected), Wirehaired Fox Terriers, West Highland White Terriers, Beagles, Shetland Sheepdogs, Airedale Terriers, mixed breed dogs
• Female dogs are 50% more commonly diagnosed with bladder transitional cell carcinoma. The reason for this may be that male dogs tend to urinate more often than females, meaning your dog has an increased time exposed to the cancer cells
• Obesity

It is common for transitional cell carcinoma to be found by your veterinarian during a routine examination, in which case the prognosis is usually much better than what it would be if the cancer is not found until symptoms are visible. For this reason, taking your dog to be examined at least once per year is essential, such as with most diseases. The sooner it is found, the better the chance for survival. Your veterinarian will do a comprehensive physical examination, which may include weight, height, body temperature, heart rate, and blood pressure. Some of the tests that may need to be done are a urinalysis, CBC (complete blood count), blood chemistry panel, urinalysis, and several images done with x-rays, MRI, ultrasound, and CT scan. A sample of the tumor(s) for microscopic evaluation can be done with a fine needle biopsy by inserting a thin needle into the tumor or the lymph nodes. The veterinarian may also need to get a larger sample for biopsy, which he can take with surgery if necessary. A test called a cystourethrogram is also performed to determine the severity of the disease. In this test, your dog will get radiologic images while urinating by inserting a tiny flexible tube (urinary catheter) to inject dye while x-rays are taken. This test can show the veterinarian how well your dog can urinate and if there are any blockages.

The best treatment for transitional cell carcinoma is to remove the tumor and any questionable tissue and lymph nodes in the area of the cancer. The problem with this is the placement of the tumor, which is usually in the neck of the bladder where it is harder to get at. Even with a skilled surgeon it is sometimes just not possible to remove all of the tumor. This surgery is usually done with an endoscopic laser guided by ultrasound, but this is not often successful. As a matter of fact, the cancer returns in almost all cases, so even if the surgeon believes he got the whole tumor, the average length of survival is less than six months. Many veterinarians get better results by removing all or a portion of the bladder, but survival rates are similarly lower in this case. Sometimes, chemotherapy combined with surgery can get better results, although the rate of survival is still not long.

Since transitional cell carcinoma is a fatal disease with no cure, many pet owners decide to just make their dog comfortable with the time he has left. If your dog is obviously in extreme pain, euthanasia may be the only answer to relieve his suffering. Your veterinarian can give you suggestions, but you are the only one who knows what is best for your dog and for you.