Surgery can be used for 3 purposes
- Making an incision in the bladder to obtain a tissue sample of the tumor
- Removing the tumor if it is not situated at the ureter outlet
- Maintaining or repairing urine flow.
Reducing the size of the tissue mass can theoretically render other treatments more successful. The smaller the tumor is, the easier it is for other treatment types to succeed. Complete removal of a transitional cell carcinoma in the bladder is often not possible because they occur a lot at the ureter outlet, or because the urethra is involved and, in some cases, because metastases are present. Surgery is rarely curative but has an important function as it opens the urinary tract, enabling the dog to urinate normally again. Another option is to place a deviation between the bladder and the urethra (because the passage to the urethra is blocked by the tumor).
How long the dog survives after placing these deviations or stents has not been extensively reported and varies between a few days to up to a year. As of note, this deviation means that most times the urinary flow is no longer controlled by a bladder sphincter and the dog becomes incontinent.
Information about the suitability of radiotherapy for transitional cell carcinomas in dogs is limited and is to be further examined.
The most common treatment of transitional cell carcinoma of the bladder consists of chemotherapy, administration of anti-inflammatory drugs or a combination of both.
Although administering this medication will not lead to a cure for most cases, certain medication can stabilize or make the disease disappear. It’s also possible that after a while, the cancer cells are no longer sensitive for the antitumoral medication. When this is the case, the treatment must be switched to the next medication. To be able to determine this moment in time, it is important to do a regular follow-up of the dog (every 1 to 2 months). In general, a treatment is maintained as long as the disease is under control, the side effects are acceptable, and the quality of life is ok. With this approach, in 75% of dogs with a transitional cell carcinoma of the bladder, the tumor can be kept under control. The quality of life is usually very good. The survival varies: it can be a year, although there are certainly dogs who do not make it this far. When anti-inflammatory drugs such as piroxicam are administered, one must be aware of the side effects of their long-term use, such as digestive issues (in particular ulcers). In case of vomiting, black diarrhea and a lack of appetite, the medication must be stopped, and the symptoms treated. After this and if appropriate, the veterinarian can advise to switch to another type of anti-inflammatory drug.
Local treatments consist of inserting chemotherapeutics into the bladder and photodynamic therapy.
Not much has been published about bladder chemotherapy in dogs. In a small study, it seemed to be well tolerated and the tumors did shrink or stopped growing after this treatment. However, serious side effects can occur when the chemo is absorbed from the bladder into the bloodstream. This treatment is therefore only advised when there are no other options left. Furthermore, after this treatment, precautions must be taken concerning the urine collection of the treated dog as the concentration of the chemotherapeutic in the urine after a bladder rinse with this chemotherapeutic is much higher than after the classic intravenous administration.
Photodynamic therapy of the bladder consists of administering a photodynamic agent (a compound that reacts with light) intravenously, after which it selectively accumulates in the tumor. After this, the tumor is illuminated via a light source inserted into the bladder. The illumination causes a chemical process in the cancer cells which have taken up the photodynamic agent after which they eventually die. The illumination can be painful.
In humans with high-grade superficial tumors of the bladder, a weakened bacterium, named bacille Calmette-Guérin, is applied into the bladder. This bacterium stimulates the immune system to recognize the tumor and to attack it. So far, few is reported about this in veterinary medicine.
Salmonella enterica serovar Typhimurium is a weakened bacterium that has been used in a similar way in dogs and led to results in some dogs. The treatment is mostly effective when only the superficial layer of the bladder wall is affected. Unfortunately, the tumor has often already penetrated the deeper tissue layers before the dog shows symptoms and is diagnosed.