# Bladder Cancer in Dogs: Causes and Early Signs Bladder cancer in dogs causes are not fully understood, but genetics, breed, age, and environmental exposures all appear to play a role. The most common form, transitional cell carcinoma, often hides behind signs that look exactly like a urinary tract infection. This article is educational and is not a substitute for veterinary diagnosis or treatment. ## Quick Answer - Transitional cell carcinoma (TCC), also called urothelial carcinoma, is the most common malignant tumor of the canine bladder and urethra [1]. - The most frequent early signs are blood in the urine, straining to urinate, and urinating small amounts very often [2]. - Bladder cancer is uncommon overall, making up less than 1% of all canine tumors [3]. - A urinary tract infection that keeps coming back after treatment, or one that clears on paper but not in symptoms, deserves a closer look. - Early diagnosis matters because the disease can often be controlled and dogs can keep a good quality of life [4]. ## What Bladder Cancer in Dogs Actually Is Your dog's bladder is lined with a stretchy tissue called transitional epithelium. Tumors that grow from this lining are called transitional cell carcinomas, or urothelial carcinomas [2]. These tumors can start in the bladder, the tube that carries urine out (the urethra), or less often in the upper urinary tract [2]. Most bladder tumors in dogs are malignant, meaning they can invade deeper into the bladder wall and spread to other parts of the body [3]. They tend to grow slowly and spread late, but when they do spread, roughly half of cases develop metastases, most often to nearby lymph nodes and the lungs [3]. Rare sites like bone, the skull, and even the cornea of the eye have been reported [3][5]. This is different from a urinary tract infection. An infection is bacteria in the urine. A tumor is a growing mass of tissue. The two can look identical from the outside, and sometimes they occur together. ## Early Signs of Bladder Cancer in Dogs That Owners Miss The tricky part of bladder cancer is that early symptoms overlap almost completely with a UTI. Many owners assume a course of antibiotics will fix it. Sometimes it does, at least for a while. ### The classic urinary signs The most common clinical signs of lower urinary tract tumors are hematuria (blood in urine), dysuria (painful or difficult urination), stranguria (straining to urinate), and pollakiuria (urinating very frequently) [2]. You might see your dog squatting many times on a walk and producing only a few drops. You might notice pink or red tinge in the urine, or blood that comes and goes. If you are seeing these patterns, our guide to [Dog Urinating Small Amounts Frequently: Causes and When to Worry](/knowledge/veterinary-medicine/digestive-and-urinary-care/dog-urinating-small-amounts-frequently) walks through what each pattern can mean. ### Signs that point away from a simple infection A few details should raise your suspicion: - Symptoms that improve on antibiotics and then return within weeks of finishing them. - Blood in the urine that is visible to the eye, not just on a dipstick. - Straining that gets worse over time instead of better. - A palpable mass or a thickened bladder wall found during a physical exam [2]. - A urethra that feels firm or cordlike on rectal exam, or a mass that can be felt [2]. Visible blood in the urine is never something to wait out. Our article on [Dog Blood in Urine: Causes and Emergency Steps](/knowledge/veterinary-medicine/digestive-and-urinary-care/dog-blood-in-urine-causes-emergency-steps) explains when this becomes urgent. ### When the tumor blocks urine flow As a tumor grows, it can narrow the urethra or press on the ureters, the tubes that carry urine from the kidneys to the bladder. This causes obstruction. Dogs with ureteral obstruction can show abdominal pain and may have an enlarged kidney that a veterinarian can feel [2]. If both ureters or the urethra are blocked, signs of uremia (waste buildup in the blood) can appear, and the dog can become very sick [2]. Obstruction is a medical emergency. A dog who cannot pass urine, is straining with nothing coming out, or is vomiting and lethargic needs to be seen right away. ## What Causes Bladder Cancer in Dogs? Known Risks and Suspects No one can point to a single cause of bladder cancer in dogs. What veterinarians and researchers have identified is a set of risk factors that make some dogs more likely than others. ### Breed and genetics Certain breeds show up again and again in bladder cancer cases. Scottish Terriers are studied closely because of their high risk. In one screening program, 41 of 120 Scottish Terriers aged 6 and older were found to have biopsy-confirmed urothelial carcinoma, including high-grade tumors, low-grade tumors, carcinoma in situ, and dysplasias that progressed to high-grade cancer [6]. That is a striking number for a cancer that is otherwise uncommon. A specific mutation called BRAF V595E has been detected in dogs with this cancer, and it can be found across the spectrum from non-cancerous urothelium to invasive carcinoma [6]. This finding matters because it may eventually help with earlier detection and prevention research [6]. Other breeds commonly mentioned by veterinarians include Shetland Sheepdogs, West Highland White Terriers, Beagles, and Wire Fox Terriers. ### Age and sex Bladder cancer is mostly a disease of middle-aged to older dogs. It can occur in either sex, though some studies suggest females may be slightly overrepresented for urethral involvement. ### Environmental exposures This is the area owners ask about most. Certain chemicals, including some herbicides and insecticides, have been discussed as possible contributors to what causes dog cancer in the urinary tract. The evidence is not as clean as we would like, and no single product has been proven to cause bladder cancer in a pet dog. Still, limiting unnecessary lawn chemical exposure and preventing your dog from licking treated surfaces is reasonable common sense. ### Chronic inflammation Long-standing irritation of the bladder lining, including repeated infections or bladder stones, is often mentioned as a possible contributor. The exact role is still being sorted out. ### What does not cause it Bladder cancer is not contagious between dogs. It is not caused by holding urine too long on a rainy day. It is not something you did wrong. ## How Veterinarians Tell Bladder Cancer Apart From a Stubborn UTI This is the central question for most owners, because the symptoms are so similar. ### Step 1: Urinalysis and urine culture A urine sample checks for blood, bacteria, crystals, and abnormal cells. A culture tells the vet whether bacteria are actually growing and which antibiotic will kill them. If your dog has been treated for a UTI more than once or twice in a short period, ask whether a culture was done. ### Step 2: Imaging Ultrasound is the most common next step. It lets the vet see the bladder wall, look for a mass, and check the kidneys and ureters. Contrast radiographs can also show tumors, particularly in the trigone region at the base of the bladder [2]. ### Step 3: Sampling the tissue The only way to confirm cancer is to look at the cells or tissue. This can be done with a catheter-assisted biopsy, cystoscopy, or surgery. A pathologist then classifies the tumor. This matters because canine urothelial carcinoma comes in several subtypes, including conventional, glandular, sarcomatoid, squamous, large nested, and tubular/microcystic forms [7]. Knowing the subtype helps guide treatment. ### Step 4: Staging If cancer is confirmed, your vet will check whether it has spread. This usually means chest X-rays and possibly lymph node sampling. | What you notice at home | What it can mean | What to do | |---|---|---| | Straining, frequent small urinations, no blood | UTI, stones, or early tumor | Routine vet visit within a few days | | Visible blood in urine, once or twice | UTI, stones, or tumor | Vet visit within 24 to 48 hours | | Symptoms return after every antibiotic course | Tumor more likely | Ask for urine culture and ultrasound | | Cannot urinate at all, vomiting, lethargic | Urethral or ureteral obstruction | Emergency visit now | ## Treatment Options for Canine Bladder Cancer Treatment depends on where the tumor is, how big it is, and whether it has spread. ### Chemotherapy Chemotherapy is generally considered the primary management for transitional cell carcinoma [1]. It is usually given as a pill or injection and is often better tolerated in dogs than in people. Your veterinarian will calculate the dose based on your dog's weight, kidney function, and overall health. ### Surgery Surgery is an option in selected cases. In two female dogs with urethral transitional cell carcinoma, surgeons removed the entire urethra and part of the bladder, then diverted urine from the bladder to the vagina [1]. Both dogs recovered without complications, and no recurrence was seen for about one year in one dog and one and a half years in the other [1]. This is a specialized procedure, not a routine option, but it shows what is possible in the right hands. ### Radiation therapy Radiation can help when a tumor is blocking urine flow. In one group of 25 dogs treated with radiation for urethral or ureteral obstruction, obstruction relief was achieved in 15 of 25 dogs (60%) [8]. Dogs treated with definitive-intent protocols had higher overall efficacy (83% versus 53%) and longer survival times than those treated with palliative protocols [8]. Relief of obstruction took a median of 8 days with definitive protocols versus 4 days with palliative ones [8]. ### Palliative care When cure is not possible, the goal shifts to comfort. Pain control, anti-inflammatories, and sometimes a stent or catheter to keep urine flowing can make a real difference. ## Recovery, Outlook, and Long-Term Management The outlook for bladder cancer in dogs varies widely. Some tumors are slow growing and can be managed for many months or longer. Others are aggressive and spread quickly, as in one case where a 15-year-old dog had metastatic lesions in 14 different sites, including the cornea [5]. The single most important factor is how early the cancer is found. With early diagnosis, the disease can be controlled in most dogs, and they can maintain a good quality of life [4]. That is why a UTI that will not quit deserves a second look. Long-term management usually includes: - Regular rechecks with ultrasound and bloodwork. - Monitoring for signs of obstruction, which can develop suddenly. - Watching for spread to the lungs or lymph nodes. - Adjusting treatment as the disease changes. - Keeping your dog comfortable, hydrated, and eating well. If your dog has other cancer concerns, our article on [Symptoms Of Dogs With Pancreatic Cancer](/knowledge/veterinary-medicine/symptom-guides/symptoms-of-dogs-with-pancreatic-cancer) covers a different set of warning signs worth knowing. ## Can You Prevent Bladder Cancer in Dogs? There is no proven way to prevent bladder cancer. You can lower some risks and catch problems earlier. - Know your breed's risk. If you have a Scottish Terrier or another high-risk breed, talk to your vet about screening. In one program, screening included urinalysis, urinary tract ultrasound, and follow-up cystoscopic biopsy [6]. - Do not ignore recurring UTIs. Repeated infections in an older dog should trigger imaging, not just another antibiotic. - Limit chemical exposure. Rinse paws after lawn treatments, and keep your dog away from freshly sprayed areas. - Keep fresh water available. Dilute urine is less irritating to the bladder lining. - Schedule senior wellness visits. A yearly exam with a urine sample catches a lot. ## Limitations and When to Contact a Veterinarian This article gives general information. Your dog's individual case needs a veterinarian who can examine, test, and treat your pet directly. **Contact an emergency clinic now if your dog:** - Cannot pass any urine despite straining - Is vomiting, weak, or collapsing - Has a distended, painful abdomen - Is crying out while trying to urinate **Contact your veterinarian the same day if your dog:** - Has visible blood in the urine for the first time - Has not urinated in 12 or more hours - Is straining with only drops coming out **Schedule a routine visit within a few days if your dog:** - Has had three or more UTIs in a year - Has symptoms that return after every antibiotic course - Is drinking and urinating more than usual - Has unexplained weight loss ## Frequently Asked Questions ### Is bladder cancer in dogs painful? It can be. Straining to urinate, bladder spasms, and tumor invasion into the bladder wall all cause discomfort. Pain management is a core part of treatment, and veterinarians have several options to keep dogs comfortable. ### Can a urinary tract infection turn into bladder cancer? No. An infection does not become cancer. However, a tumor can cause repeated infections by irritating the bladder lining, so a UTI that keeps coming back can be the first clue that something else is going on. ### How long can a dog live with bladder cancer? It depends heavily on the tumor type, location, and how early it is found. Some dogs live many months to over a year with treatment. Dogs with obstruction that is relieved by radiation have documented survival times, and outcomes are better with definitive-intent protocols [8]. ### Are some dog breeds more likely to get bladder cancer? Yes. Scottish Terriers have a notably high risk, with 41 of 120 screened dogs aged 6 and older having biopsy-confirmed urothelial carcinoma [6]. Shetland Sheepdogs, West Highland White Terriers, Beagles, and Wire Fox Terriers are also commonly mentioned. ### Does pet insurance cover bladder cancer treatment? Coverage depends on your specific policy, when it was purchased, and whether the cancer is considered pre-existing. Call your insurer directly to ask about diagnostics, chemotherapy, radiation, and surgery before you commit to a treatment plan. ## Related Articles - [Signs Of Uti In Dogs](/knowledge/veterinary-medicine/clinical-methods/signs-of-uti-in-dogs) - [Symptoms Of Dogs With Pancreatic Cancer](/knowledge/veterinary-medicine/symptom-guides/symptoms-of-dogs-with-pancreatic-cancer) - [Dog Uti Symptoms](/knowledge/veterinary-medicine/symptom-guides/dog-uti-symptoms) - [Dog Urinating Small Amounts Frequently: Causes and When to Worry](/knowledge/veterinary-medicine/digestive-and-urinary-care/dog-urinating-small-amounts-frequently) - [Dog Blood in Urine: Causes and Emergency Steps](/knowledge/veterinary-medicine/digestive-and-urinary-care/dog-blood-in-urine-causes-emergency-steps) - [Why Is My Dog having bloody urine? Cystitis Bladder Stones and UTI Guide](/knowledge/veterinary-medicine/symptom-guides/why-is-my-dog-having-bloody-urine-cystitis-bladder-stones-and-uti-guide) - [Bladder Cancer in Dogs: Survival Rate and Prognosis](/knowledge/veterinary-medicine/senior-and-chronic-care/bladder-cancer-dogs-survival-prognosis) - [Bladder Cancer in Dogs: Medication Options Explained](/knowledge/veterinary-medicine/senior-and-chronic-care/bladder-cancer-dogs-medication) - [Bladder Cancer vs Bladder Stones on Dog Ultrasound](/knowledge/veterinary-medicine/vet-visit-decisions/bladder-cancer-stones-dog-ultrasound) ## References 1. [Case Report: Surgical excision of urethral transitional cell carcinoma by total urethrectomy combined with partial cystectomy and vesicovaginal urinary diversion in two female dogs](https://pubmed.ncbi.nlm.nih.gov/42158320/). Frontiers in veterinary science, 2026. 2. [Neoplasia of the Urinary System in Dogs and Cats - Urinary System](https://www.merckvetmanual.com/urinary-system/noninfectious-diseases-of-the-urinary-system-in-small-animals/neoplasia-of-the-urinary-system-in-dogs-and-cats). Merck Veterinary Manual. 3. [A case of canine urothelial carcinoma of the urinary bladder with skull and skeletal metastases](https://pubmed.ncbi.nlm.nih.gov/41992979/). Australian veterinary journal, 2026. 4. [A review of the current standing of microRNA expression in canine urothelial carcinoma](https://pubmed.ncbi.nlm.nih.gov/39047791/). American journal of veterinary research, 2024. 5. [Corneal stromal metastasis of urothelial carcinoma in a dog](https://pubmed.ncbi.nlm.nih.gov/42636554/). Research in veterinary science, 2026. 6. [BRAFV595E mutation detected across the disease spectrum from non-neoplastic urothelium to invasive urothelial carcinoma in dogs](https://pubmed.ncbi.nlm.nih.gov/42716084/). Journal of the American Veterinary Medical Association, 2026. 7. [Histologic and immunohistochemical characterization and frequency of rare subtypes of canine invasive urothelial carcinoma](https://pubmed.ncbi.nlm.nih.gov/41879030/). Veterinary pathology, 2026. 8. [Radiation therapy as a treatment for urinary obstruction secondary to urothelial carcinoma in dogs](https://pubmed.ncbi.nlm.nih.gov/41742557/). Journal of veterinary internal medicine, 2026. ## Further Reading - [Noninfectious Diseases of the Urinary System in Dogs - Dog Owners (Merck Veterinary Manual)](https://www.merckvetmanual.com/dog-owners/kidney-and-urinary-tract-disorders-of-dogs/noninfectious-diseases-of-the-urinary-system-in-dogs) - [Merck Veterinary Manual: Dog Owners](https://www.merckvetmanual.com/dog-owners) - [Cornell Richard P. Riney Canine Health Center: Canine Health Information](https://www.vet.cornell.edu/departments-centers-and-institutes/riney-canine-health-center/canine-health-information)