Canine Cancer: Transitional Cell Carcinomas- What Does It Mean For Your Dog?

Last updated:
April 25, 2023
A woman gently holding her dog at a park

Transitional cell carcinoma isn’t the kind of diagnosis that most people are aware of. What does it mean? How do you help? What will happen to your dog? This blog is here to help answer some of your questions.

What is transitional cell carcinoma?

Transitional cell carcinoma (TCC) is a tumor that arises in the urinary tract of your dog. TCC can develop anywhere from the bladder to the urethra, and the growth of the tumor can create issues with letting urine pass out of the tract.1,2 On top of the health detriment that comes from the cancer itself, the blockage of the urinary tract can also cause damage to the liver. Urinary bladder cancer makes up 2% of all canine cancer, meaning tens of thousands of dogs are affected every year worldwide.3

Signs and symptoms 

Signs of transitional cell carcinomas are often very similar to many other, less-threatening ailments such as bladder stones, UTIs, and bladder infections: having a difficult time urinating, blood in their urine, and not being able to urinate.1 

Often the diagnosis of TCC will start with a diagnosis of an infection, treatment for a UTI or a bladder infection will include antibiotic therapy. If a dog is diagnosed with an infection and given antibiotics but only sees temporary, or no improvement, a vet will re-evaluate and look closer for signs of a tumor.4 

As with many cancers, there is no clear cause for developing transitional cell carcinoma, although some correlation has been found between the cancer and smaller breed dogs such as Scottish terriers, West Highland terriers, dachshunds, and Shetland sheepdogs. As with any cancer, the expectation is that exposure to carcinogens has an impact on the development of the disease, with herbicide-treated lawns being the main suspect in this particular cancer.2 

There is also a higher rate of female dogs developing TCC than their male counterparts, which has been attributed to the male dog’s likelihood of using urine marking more often than females.2 

How is it diagnosed? 

Depending on the location of the tumor there are different factors in how the tumor is found and diagnosed. For some patients, the tests needed will be obvious because their parent has brought them in due to signs of urinary tract issues—like bloody urine or difficulty urinating. Tests will be performed on urine samples for anything that may cause those issues, be that a urinary tract infection, bladder infection, or TCC. Blood work also helps to identify the overall health status of the patient.1,5 

For the majority of transitional cell carcinomas cases, the location of the tumor is not one that a vet would be able to feel through a physical exam. It’s possible for an ultrasound to identify the mass and find the location on the body. If the growth is accessible, a biopsy will be done to confirm the nature of the cells in the mass. TCC is typically diagnosed through histopathology of tissue gathered by cystoscopy, surgery, or catheter.3 The veterinary oncologist will examine the samples in very thin layers to see how the tissue changes under a microscope.

If there are clear signs of a tumor your vet may also have some x-rays done to check for any cancer that may have spread to other areas of the body, commonly the lungs. 

What is the treatment for TCC?

For a majority of dogs that develop transitional cell carcinomas, the tumors develop in a location that doesn’t lend itself to positive outcomes for surgical removal. The most common location for TCC to develop in a dog’s urinary tract is at the neck of the bladder, which if removed or operated on can lead to issues of incontinence, meaning your dog would lose the ability to control when they use the bathroom. And, more significantly, in a majority of cases where surgery is an option, it would not be able to cure or effectively treat the tumor. Surgery may be used as a supplemental treatment to make further treatment methods more effective by removing mass from the tumor where possible, but complete removal is unlikely.1

Dogs that are unable to urinate may require the insertion of a urethral stent. A stent is a small tube that allows the dog to be able to pass urine and can be placed using a moving x-ray machine in a relatively simple procedure. 

Some dogs will be treated with chemotherapy as the main attack on the tumor. Unfortunately, as with most of the other treatments for TCC, the response to treatment through chemotherapy is almost always partial. But the quality of life that a dog has while going through chemotherapy treatment is likely to be as close to the quality they had before the development of TCC. Maintaining their quality of life is one of the benefits of choosing chemotherapy treatment.

Another common treatment is the use of radiation therapy to target the tumor. The results of radiation therapy are often an improvement in symptoms and a decrease in the size of the tumor. Though there is no way to completely remove it, a decrease in size can make the dog’s life with the tumor more bearable, especially when paired with improved or lessened symptoms. Some dogs treated with radiation therapy will also be given a chemotherapy treatment that works as a sensitizer for the radiation therapy, amplifying the cancer-killing effects of the radiation therapy.1,4 

Prognosis—What should you expect from TCC?

The sad truth is that transitional cell carcinoma is not curable and is a fatal disease. While there is treatment available, the goal of that treatment is to uphold the quality of life for the dog receiving it.1,5 

TCC impacts patients more than just having a tumor. Depending on the location of the tumor, there is potential for it to create a blockage from the urethra or the ureters, which can lead to kidney failure because the patient is unable to release urine effectively—or at all—from their body. And, as with all cancers, there is also the potential for the disease to spread and impact other parts of the body. Canine TCC is often locally advanced at the time of diagnosis. For about 20% of cases, the cancer has spread to areas away from the urinary tract, called distant metastasis, which is, unfortunately, associated with a worse prognosis. More than half of dogs with TCC have distant metastases at death.3

The average span of time that a dog can survive after a TCC diagnosis with treatment is anywhere from six to nine months, with a decent quality of life. 

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