Transitional cell carcinoma (bladder cancer) in dogs.

What it is

Transitional cell carcinoma (TCC), now formally known in human medicine as urothelial carcinoma, arises from the cells lining the urinary tract. In dogs it most often originates in the trigone region of the bladder — anatomically inconvenient for surgery, since that's where the ureters and urethra meet.

Scottish Terriers have a markedly elevated breed risk; West Highland White Terriers, Shetland Sheepdogs, Beagles, and Wire Fox Terriers are also over-represented. Exposure to older-generation lawn herbicides has been associated in epidemiologic studies, particularly in predisposed breeds.

Signs to watch for

• Frequent straining to urinate, with small amounts. Often misdiagnosed as recurring UTI initially.
• Blood in the urine. Can be visible or only detected on urinalysis.
• Urinary accidents in a previously house-trained dog.
• Lameness or stiffness in some cases — TCC can metastasize to bone.

How veterinarians diagnose it

A urinalysis showing red blood cells and atypical cells raises suspicion. The CADET BRAF mutation test (urine-based, non-invasive) detects the BRAF V595E mutation present in roughly 80% of canine TCC and is a useful screening tool for high-risk breeds.

Imaging — abdominal ultrasound is the standard, and the radiologist can usually visualize the mass and measure its size. Cystoscopy with biopsy gives histopathology when needed; traumatic catheterization or 'catch' samples are alternatives.

Staging includes chest radiographs and abdominal ultrasound of regional lymph nodes; bone radiographs if the dog is lame.

What treatment usually looks like

• NSAIDs (piroxicam or meloxicam) have direct anti-tumor activity in canine TCC and are often a backbone of therapy — particularly important because surgical cure is rarely feasible.
• Chemotherapy — vinblastine, mitoxantrone, or carboplatin in various combinations or sequences with NSAIDs.
• Toceranib (Palladia) is used by some oncologists, sometimes combined with NSAIDs.
• Stereotactic radiation to the bladder is an emerging option at referral centers.
• Stenting if the tumor causes urethral obstruction — a quality-of-life intervention.

Prognosis

Bladder TCC is rarely curable but is often manageable. Published median survival with combination therapy (NSAID + chemo) is in the range of about 6–12 months from diagnosis with substantial individual variation — many dogs feel well during treatment.

Tumor location, ureteral or urethral obstruction at diagnosis, and presence of metastasis are the main negative prognostic factors. Early intervention before obstruction develops generally improves the journey.

Questions to ask your vet

• Has the diagnosis been confirmed — by cytology, biopsy, or CADET BRAF testing?
• What's the tumor's location and is it threatening the ureters or urethra?
• Are we starting an NSAID (piroxicam)? Will we add chemotherapy?
• What signs of obstruction should I watch for? Who do I call after hours?
• Is stereotactic radiation available within reach?

Where to learn more

Veterinary teaching hospitals at most accredited US vet schools maintain owner-facing fact sheets on common cancers. Peer-reviewed journals — JAVMA, Veterinary and Comparative Oncology, Frontiers in Veterinary Science — are accessible through PubMed. The American College of Veterinary Internal Medicine (ACVIM) and the Veterinary Cancer Society publish consensus statements you can ask your vet to walk you through.

For clinical trials enrolling dogs with this diagnosis, see the SciRouter Vet trial finder — we index AVMA, NCI COTC, and twelve university registries.