Malignant Tumor of the Urinary Tract in Dogs (Urothelial Carcinoma)

  • Occurrence: rarer
  • Location of disease: Abdomen/pelvis
Author: Dr. med. vet. Gisa Löwe | Last modified: 12.08.2026
Open table of contents

When to visit the vet?

Non-urgent see a veterinarian within 2–3 days

?

If the condition worsens / symptoms persist, consult a veterinarian.

Download/Print

Definition

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.

Das Wichtigste auf einen Blick

Urothelial carcinoma in dogs develops from the cells lining the urinary tract and is caused by genetic mutations leading to uncontrolled growth. Although the exact causes are unknown, genetic predispositions, environmental factors, and possibly diet play a role. Certain dog breeds such as Scottish Terriers, West Highland White Terriers, and Beagles are more susceptible. Exposure to chemicals like 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 clinical examination, urine analysis, imaging, and biopsy. Treatment often requires surgery, chemotherapy, and radiation therapy to control tumor growth and improve quality of life. The prognosis is guarded to poor, as the cancer is aggressive and prone to metastasis. Early diagnosis and good response to treatment can improve the prognosis. Prevention measures include avoiding carcinogens and a healthy diet. Regular veterinary examinations are important to detect early changes, especially in at-risk breeds.

Ursachen

Urothelial carcinoma fundamentally develops from the transitional cells that line the mucous membrane of the urinary tract. These cells can 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 development are not fully understood; however, several factors can increase the risk. These include genetic predispositions, environmental factors, and possibly dietary 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 exposure to certain chemicals, such as pesticides and herbicides, can increase the risk of developing urothelial carcinoma. Similarly, tobacco smoke is a known risk factor for bladder cancer in humans and could also play a role in dogs exposed to passive 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. 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 as 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 often indicate that the tumor is already advanced.

Diagnose

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

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

Imaging procedures such as ultrasound or X-rays of the abdomen can be used to determine the exact location and size of the tumor and to establish whether there are metastases. A contrast study of the urinary tract, urethrocystography, 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 through a cystoscopy, where a flexible endoscope is inserted into the bladder, or through a surgical biopsy. The histopathological examination of the tissue can confirm the presence of cancer cells and assess the degree of malignancy.

Therapie

The treatment of urothelial carcinoma 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 is 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 frequently used to slow tumor growth and control metastasis. A combination of medications such as mitoxantrone and meloxicam has proven effective, although the response to treatment can vary individually.

Radiation therapy may be an option for dogs where the tumor cannot be surgically removed. It can help alleviate 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 frequently occur with this type of cancer.

Prognose und Nachsorge

The prognosis for dogs with urothelial carcinoma is often guarded to poor, as the disease is generally 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 diagnosed early and responding 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 disease progression and adjust treatment accordingly.

Prävention

Since the exact causes of urothelial carcinoma are not fully understood, there is no guaranteed prevention method. Nevertheless, some measures can be taken to reduce the risk. An important step is minimizing contact with known carcinogens. This includes avoiding pesticides and herbicides in the home environment as well as 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 examinations are important to detect changes in health status early. For breeds with an increased risk of urothelial carcinoma, closer monitoring may be advisable.

Ausblick auf aktuelle Forschung

Urothelial carcinoma in dogs is the most common malignant tumor of the lower urinary tract, predominantly in the area of the bladder, trigone, and proximal urethra. The disease is clinically insidious because it often initially resembles chronic cystitis. The most important advance in recent years therefore lies in earlier and less invasive diagnosis, especially through molecular urine tests. (pubmed.ncbi.nlm.nih.gov, pubmed.ncbi.nlm.nih.gov)

A central research field is tumor biology. Many canine urothelial carcinomas carry a BRAF mutation that can be detected in urine. This has significantly changed diagnostics and is increasingly directing research toward molecular subgroups, i.e., the question of which Tumors are biologically different and should therefore also be treated differently. In parallel, liquid biopsy methods are being investigated to better monitor progression, treatment response, and relapses. (pubmed.ncbi.nlm.nih.gov, pubmed.ncbi.nlm.nih.gov)

Therapeutically, the focus is on targeted and combined treatments. Standard approaches such as NSAID (non-steroidal anti-inflammatory drug) and chemotherapy can often slow tumor growth but usually do not cure. Therefore, research is testing new strategies, including targeted signaling pathway therapies, better combinations, and immuno-oncological approaches. At the same time, the dog is an important model in comparative oncology because canine urothelial carcinoma shows many biological parallels to invasive bladder carcinoma in humans. (pubmed.ncbi.nlm.nih.gov, pubmed.ncbi.nlm.nih.gov)

Overall, the outlook is good: Research is clearly moving toward molecular diagnostics, more precise monitoring of progression, and individualized therapy.

Frequently Asked Questions (FAQs)

1. What is urothelial carcinoma?
Urothelial carcinoma (also transitional cell carcinoma or TCC) is a malignant tumor that originates from the mucosal cells of the urinary tract. In dogs, the bladder is most commonly affected, followed by the urethra, ureter, and renal pelvis. It is the most common tumor of the lower urinary tract in dogs.
2. Which dogs are particularly at risk?
Predisposed are older female dogs, neutered animals, and certain breeds such as Scottish Terriers (with the highest known risk), West Highland White Terriers, Shetland Sheepdogs, Beagles, and Wire Fox Terriers. Overweight, pesticide/herbicide exposure, and a lack of vegetable-rich diet are considered risk factors.
3. What symptoms do affected dogs show?
Typical are hematuria (bloody urine), frequent urinary urgency, painful urination, and sometimes difficulty urinating up to complete urinary retention when the tumor obstructs the urethra. The symptoms are often initially misdiagnosed as a urinary tract infection but do not respond permanently to antibiotics.
4. How is the diagnosis made?
Ultrasound of the bladder usually shows a nodular or polypoid thickening of the bladder wall, frequently in the trigone area. Cytological examination of the urine sediment, the CADET BRAF test (mutation-based urine test), and ultimately histology from a biopsy confirm the diagnosis. CT or X-ray clarify the extent of spread.
5. How is urothelial carcinoma treated?
Complete surgical removal is usually not possible because the tumors often sit at the trigone. Medical therapy with non-steroidal anti-inflammatory agents (piroxicam, meloxicam) and chemotherapy with mitoxantrone, vinblastine, or toceranib is standard. In selected cases, stent implantation or radiation therapy may be considered.
6. What role does the CADET BRAF test play?
In about 85 percent of urothelial carcinomas, a specific BRAF mutation can be detected in the urine. The CADET BRAF test is non-invasive, highly specific, and allows early diagnosis before the tumor mass is visible on ultrasound. It is increasingly recommended as a screening test in predisposed breeds.
7. What is the prognosis for urothelial carcinoma?
The prognosis is limited. With chemotherapy and non-steroidal anti-inflammatory agents, the median survival time is about 8 to 12 months. Tumors at the bladder apex have a better prognosis because they are more amenable to surgical removal. Without treatment, the disease usually leads to death within a few months.
8. How high is the risk of metastasis?
At the time of diagnosis, about 20 percent of dogs already have metastases, especially in the sublumbar lymph nodes and lungs. Over the course of the disease, around half of the patients develop metastases. Complete staging with thoracic X-ray or CT before starting therapy is therefore important.
9. When is a urethral stent necessary?
A stent is placed when the tumor obstructs the urethra so severely that urination is no longer possible. The stent is placed minimally invasively under fluoroscopy and creates an open channel. It significantly improves quality of life but can lead to incontinence as it disrupts sphincter function.
10. How can the risk be addressed?
For predisposed breeds such as the Scottish Terrier, regular screening examinations with urine analysis and CADET BRAF test from middle age are advisable. Avoiding pesticide exposure (especially herbicides on lawns), weight control, and a vegetable-rich diet can reduce the risk.

Literatur

  • Chu, K. T., Nekouei, O., & Giuliano, A. (2025). Treatment outcomes of dogs with transitional cell carcinoma. Frontiers in Veterinary Science, 12, Article 1486786. https://doi.org/10.3389/fvets.2025.1486786
  • Maeda, S., Sakai, K., Kaji, K., Iio, A., Nakazawa, M., Motegi, T., Yonezawa, T., & Momoi, Y. (2022). Lapatinib as first-line treatment for muscle-invasive urothelial carcinoma in dogs. Scientific Reports, 12, Article 4. https://doi.org/10.1038/s41598-021-04229-0
  • Griffin, M. A., Culp, W. T. N., & Rebhun, R. B. (2018). Lower urinary tract neoplasia. Veterinary Sciences, 5(4), Article 96. https://doi.org/10.3390/vetsci5040096
  • Fulkerson, C. M., & Knapp, D. W. (2015). Management of transitional cell carcinoma of the urinary bladder in dogs: A review. The Veterinary Journal, 205(2), 217–225. https://doi.org/10.1016/j.tvjl.2015.01.017
  • Mochizuki, H., Shapiro, S. G., & Breen, M. (2015). Detection of BRAF mutation in urine DNA as a molecular diagnostic for canine urothelial and prostatic carcinoma. PLOS ONE, 10(12), Article e0144170. https://doi.org/10.1371/journal.pone.0144170
  • Decker, B., Parker, H. G., Dhawan, D., Kwon, E. M., Karlins, E., Davis, B. W., Ramos-Vara, J. A., Bonney, P. L., McNiel, E. A., Knapp, D. W., & Ostrander, E. A. (2015). Homologous mutation to human BRAF V600E is common in naturally occurring canine bladder cancer—Evidence for a relevant model system and urine-based diagnostic test. Molecular Cancer Research, 13(6), 993–1002. https://doi.org/10.1158/1541-7786.MCR-14-0689