CONDITION
Transitional Cell Carcinoma
Transitional cell carcinoma is the most common bladder cancer in dogs, arising from the cells lining the urinary tract, typically occurring in older dogs and causing urinary signs that can initially resemble infection or other bladder conditions.
Why this matters now
Transitional cell carcinoma predominantly affects older dogs, typically over nine years of age. Scottish Terriers have a dramatically increased risk—estimated at 18-20 times higher than other breeds. Shetland Sheepdogs, West Highland White Terriers, Beagles, and Wire Fox Terriers also show breed predisposition. Females are affected more often than males.
The tumour typically develops in the bladder wall, often at the trigone—the area where the ureters enter and the urethra exits. As it grows, the tumour invades the bladder wall and may obstruct urine flow. Local spread to nearby lymph nodes is common, and metastasis to distant sites including lungs and bones can occur as the disease progresses.
Signals & patterns
Early signals
Blood in the urine
Pink, red, or brown discolouration of urine, which may be intermittent initially.
Frequent urination attempts
Straining to urinate or making frequent trips to urinate with small volumes produced.
Apparent urinary infections that recur
Signs that improve temporarily with antibiotics but return, or fail to fully resolve.
Urinary accidents
Previously house-trained dogs may have accidents due to urgency or discomfort.
Later signals
Difficulty urinating
Straining with minimal urine production as the tumour obstructs the outflow.
Complete urinary obstruction
Inability to urinate despite repeated attempts, representing a significant complication.
Weight loss
Progressive weight loss as the cancer advances and affects overall health.
Hind limb weakness or lameness
May occur if the tumour spreads to the spine or pelvis, affecting nerves or bones.
Click to read about the biological mechanisms
How this is usually investigated
Assessment aims to confirm the diagnosis, determine the extent of the tumour, and evaluate for spread to other organs, informing discussions about management options and prognosis.
Urinalysis
Urine cytology
Abdominal ultrasound
BRAF mutation test
Cystoscopy
CT scan
Chest radiographs
Options & trade-offs
Management depends on tumour location, extent of disease, and overall health, with various approaches aimed at controlling tumour growth, maintaining urinary function, and supporting quality of life.
Non-steroidal anti-inflammatory drugs
COX-inhibiting medications that may have direct anti-tumour effects
Trade-offs: Can slow progression; well tolerated by most dogs; foundation of many treatment protocols; gastrointestinal side effects possible.
Chemotherapy
Drugs to slow tumour growth and control disease spread
Trade-offs: Can provide meaningful disease control; side effects generally manageable; various protocols available; requires monitoring.
Metronomic chemotherapy
Low-dose, continuous oral chemotherapy combined with NSAIDs
Trade-offs: Convenient home administration; fewer side effects than conventional dosing; sustained disease control possible.
Surgery
Removal of the tumour when location permits
Trade-offs: Rarely curative due to typical trigone location; may help selected cases; specialist surgical techniques expanding options.
Urethral stent placement
Metal mesh tube placed to relieve urinary obstruction
Trade-offs: Restores urination when tumour blocks outflow; does not treat the cancer; complications possible; maintains quality of life.
Radiation therapy
Targeted radiation to control local tumour growth
Trade-offs: May help control local disease; requires specialist facilities; can cause urinary side effects; palliative benefit possible.
Palliative care
Focus on comfort and quality of life as priority
Trade-offs: Appropriate when other treatments not suitable; emphasises comfort over disease control; supports dignified remaining time.
Common misconceptions
"Blood in the urine in older dogs is always just a urinary tract infection"
While infections are common, persistent or recurrent bloody urine in older dogs, especially predisposed breeds, warrants investigation for underlying bladder tumours.
"Bladder cancer means only days to weeks of survival"
With appropriate treatment, many dogs with transitional cell carcinoma live comfortably for months, and some survive a year or longer.
"Nothing can be done for dogs with bladder cancer"
Multiple treatment options can provide disease control and maintain quality of life; palliative approaches support comfort when curative intent is not possible.
Owners of older dogs experiencing urinary problems, particularly those with breeds at higher risk, may recognise the value of thorough investigation when signs persist or recur. Understanding that bladder cancer, while serious, can often be managed to maintain quality of life helps frame realistic expectations and supports informed discussions about care.
Last reviewed: 24 April 2026 · Dr Alastair Greenway MRCVS