Urothelial Carcinoma (Transitional Cell Carcinoma of the Urinary Tract) in Dogs

  • Occurrence: rarer
  • Location of illness: Abdomen/pelvis
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Urothelial carcinoma, also known as transitional cell carcinoma, is a malignant tumor disease that affects the lining of the urinary tract in dogs. It is the most common form of bladder cancer in dogs and can also affect the urethra and prostate.

The most important facts at a glance

Urothelial carcinoma in dogs develops from the cells that line the mucous membrane of the urinary tract, and it is caused by genetic mutations that lead to uncontrolled growth. Although the exact causes are not known, genetic predispositions, environmental factors, and possibly nutrition play a role. Certain dog breeds such as Scottish Terriers, West Highland White Terriers, and Beagles are more susceptible. Contact with chemicals such as pesticides and herbicides, as well as passive smoking, increases the risk. Symptoms include difficulty urinating, frequent urination in small amounts, blood in the urine, uncontrolled urination, abdominal pain, and loss of appetite. Diagnosis includes a clinical examination, urinalysis, imaging, and a biopsy. Treatment often requires surgery, chemotherapy, and radiation therapy to control tumor growth and improve quality of life. The prognosis is guarded to poor because the cancer is aggressive and tends to metastasize. Early diagnosis and good response to treatment can improve the prognosis. Prevention measures include avoiding carcinogens and eating a healthy diet. Regular veterinary check-ups are important to detect early changes, especially in at-risk breeds.

Causes

Basically, urothelial carcinoma develops from the transitional cells that line the mucous membrane of the urinary tract. These cells have the ability to stretch and contract, which is crucial for the function of the bladder and urinary tract. During malignant transformation, the cells undergo genetic mutations that lead to uncontrolled growth and tumor formation.

The exact causes of urothelial carcinoma are not fully understood, but there are several factors that can increase the risk. These include genetic predispositions, environmental factors, and possibly nutritional influences. Certain breeds such as Scottish Terriers, West Highland White Terriers, and Beagles appear to have a higher susceptibility to this type of tumor.

Environmental factors also play a role. There is evidence that contact with certain chemicals, such as pesticides and herbicides, can increase the risk of developing urothelial carcinoma. In addition, tobacco smoke is a known risk factor for bladder cancer in humans and may also play a role in dogs who passively smoke.

Hormonal influences and chronic inflammatory conditions of the urinary tract are also discussed as possible risk factors. Chronic inflammatory conditions can lead to increased cell turnover, which increases the likelihood of genetic mutations that can ultimately lead to cancer.

Symptoms

Rare symptoms:

The symptoms of urothelial carcinoma in dogs can be varied and depend on the size and location of the tumor. The most common signs include bloody urine (hematuria), which can be both visible and microscopic. This is often one of the first symptoms noticed by owners.

In addition, dogs may show frequent urination (pollakiuria), pain or difficulty urinating (dysuria). In some cases, there may be a complete blockage of the urinary tract, which is a medical emergency because the dog cannot urinate.

Other symptoms may include general signs of discomfort such as loss of appetite, weight loss, lethargy, or changes in behavior. These non-specific symptoms are often an indication that the tumor is already advanced.

Diagnosis

The diagnosis of urothelial carcinoma usually begins with a thorough clinical examination and anamnesis. The veterinarian will ask about the symptoms and perform a physical examination to detect signs of urinary tract obstruction or other physical changes.

A urinalysis is an important first step to confirm the presence of blood or abnormal cells in the urine. A urine cytology can help identify tumor cells, although this is not always possible.

Imaging techniques such as ultrasound or X-rays of the abdomen can be used to determine the exact location and size of the tumor and to determine whether there are metastases. A contrast study of the urinary tract, known as urethrography, can also be helpful in assessing the extent of the disease.

A definitive diagnosis usually requires a biopsy of the tumor tissue. This can be done by cystoscopy, in which a flexible endoscope is inserted into the bladder, or by surgical biopsy. Histopathological examination of the tissue can confirm the presence of cancer cells and assess the degree of malignancy.

Therapy

The treatment of urothelial carcinomas in dogs is often complex and requires a multimodal approach. Surgery, chemotherapy, and radiation therapy are the mainstays of treatment.

Surgical interventions may be considered if the tumor is localized and complete removal appears possible. Since the bladder is a vital organ, the extent of resection may be limited, and complete removal of the tumor is often difficult.

Chemotherapy is often used to slow tumor growth and control metastasis. A combination of drugs such as mitoxantrone and piroxicam has proven effective, although the response to treatment may vary individually.

Radiation therapy may be an option for dogs in whom the tumor cannot be surgically removed. It can help relieve symptoms and control tumor growth.

Palliative treatments aimed at improving the dog’s quality of life are also important. These include pain management and the treatment of urinary tract infections, which are common with this type of cancer.

Prognosis and follow-up care

The prognosis for dogs with urothelial carcinoma is often guarded to poor, as the disease is typically aggressive and has a tendency to metastasize. Survival time can vary greatly and depends on factors such as tumor stage, treatment, and the dog’s individual response.

Dogs that are diagnosed early and respond well to treatment may have a better prognosis. However, it is important to note that a complete cure is rare, and treatment often aims to improve quality of life and control the disease.

Regular follow-up examinations are crucial to monitor the progress of the disease and adjust treatment accordingly.

Prevention

Since the exact causes of urothelial carcinoma are not fully known, there is no guaranteed way to prevent it. However, some measures can be taken to reduce the risk.

An important step is to minimize contact with known carcinogens. This includes avoiding pesticides and herbicides in the home environment and reducing exposure to tobacco smoke.

A healthy diet can also play a role in prevention. Feeding a balanced, high-quality diet can help strengthen the immune system and promote overall health.

Regular veterinary check-ups are important to detect changes in health early. In breeds that have an increased risk of urothelial carcinoma, closer monitoring may be useful.

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