Cancer in Scottish Terriers: Bladder Cancer, Risk Factors, and Early Detection

The cancer that defines Scottish Terrier health is bladder cancer, specifically invasive urothelial carcinoma, also called transitional cell carcinoma or TCC. Scotties have roughly 20 times the risk of mixed-breed dogs, the highest breed risk reported in North American veterinary teaching hospital data (Knapp et al., 2014). In a Purdue University screening study of 120 Scotties aged six and older with no urinary symptoms, 27% were found to have bladder cancer over three years (Dhawan et al., 2022).

That is the discouraging part. The encouraging part is that bladder cancer in Scotties is one of the few canine cancers where owners have evidence-based things to do: limit exposure to herbicide-treated lawns (Glickman et al., 2004), consider adding vegetables to the diet (Raghavan et al., 2005), and talk with a veterinarian about screening, which in the Purdue study found cancer before any symptoms appeared (Dhawan et al., 2022).

This article focuses on bladder cancer because that is where the Scottie-specific evidence is strongest. Scotties can develop any cancer that affects dogs.

Key Points

• Scottish Terriers have about 20 times the risk of bladder cancer compared with mixed-breed dogs (Knapp et al., 2014).
• In most breeds, female dogs are affected about twice as often as males, but in Scotties that difference largely disappears, so male Scotties are not protected (Knapp et al., 2014).
• Scotties exposed to lawns treated with herbicides had higher odds of bladder cancer in a case-control study, and the authors advised minimizing access to lawns treated with phenoxy herbicides (Glickman et al., 2004).
• Scotties that ate vegetables at least three times a week had about 70% lower odds of bladder cancer in a separate case-control study (Raghavan et al., 2005).
• The early signs, such as blood in the urine and straining, look like a urinary tract infection, and delayed diagnosis after repeated antibiotic courses is common (Ackley, 2026).
• In screened Scotties, cancer was often found before blood appeared in the urine at all (Dhawan et al., 2022), so a normal urinalysis does not rule it out.

Detailed Explanation

What Bladder Cancer Is

Invasive urothelial carcinoma arises from the cells lining the bladder. In dogs, most of these tumors are intermediate to high grade, they are most often found in the trigone, the region near the bladder's outlet, and more than half of dogs have spread to distant sites by the time of death (Ackley, 2026). Location matters: advanced disease can obstruct the ureters that carry urine from the kidneys, and complete surgical removal is often not possible at later stages (Ackley, 2026).

The mean age at diagnosis across dogs is 9 to 11 years (Ackley, 2026). In the Purdue screening study, Scotties whose cancer was found through screening had a median age of 9.7 years at diagnosis, with a range of 6.3 to 12.9 (Dhawan et al., 2022).

How High Is the Scottie Risk?

Very high, and consistently so across sources. A review of cases from the Veterinary Medical Database at North American veterinary teaching hospitals placed Scottish Terriers at the top of the breed risk list, and earlier estimates put the increase at 16 to 20 times that of mixed-breed dogs (Knapp et al., 2014). Other breeds with increased risk, though far lower than the Scottie, include West Highland White Terriers, Shetland Sheepdogs, and Beagles (Knapp et al., 2014; Dhawan et al., 2022).

The most striking number comes from the screening study itself. The researchers planned the study expecting, based on a Scottie breed health survey, that 25% to 33% of enrolled dogs would develop bladder cancer within three years. They found biopsy-confirmed cancer in 32 of 120 dogs, or 27% (Dhawan et al., 2022). Those were dogs aged six and older whose owners had volunteered for screening, so the figure describes that group rather than every Scottie, but it is a sobering one.

Male Scotties Are Not Protected

Across dogs generally, bladder cancer affects females roughly twice as often as males. In the Veterinary Medical Database analysis, the female to male ratio among affected mixed-breed dogs was 1.9 to 1, but among 79 affected Scottish Terriers it was 0.8 to 1, so males slightly outnumbered females (Knapp et al., 2014). General advice that bladder cancer is mainly a concern in older spayed females does not apply to this breed.

Why It Gets Missed

The classic signs of bladder cancer are blood in the urine, difficult or painful urination, and frequent urination (Ackley, 2026). Every one of those signs is also a sign of a urinary tract infection, and the two often occur together: an estimated 55% of dogs with this cancer have at least one positive urine culture (Ackley, 2026).

The result is a predictable pattern. A dog with bladder cancer is treated for an infection, improves temporarily, relapses, and is treated again while the tumor grows. The MSPCA-Angell internal medicine service advises that persistent or recurrent urinary signs despite appropriate antibiotics warrant further investigation, and that in middle-aged and older dogs of high-risk breeds, it is appropriate to evaluate for bladder cancer at the first presentation (Ackley, 2026).

For a Scottie owner, the practical translation is this: a urinary tract infection in a middle-aged or older Scottie deserves a conversation about imaging, not only a prescription.

Blood in the Urine Is Not a Reliable Early Warning

Many owners assume they will see blood before anything serious happens. The screening study found otherwise. Among Scotties diagnosed with cancer through screening, only five had more than a trace of red blood cells in the urine at the time of diagnosis (Dhawan et al., 2022). Most were found because an ultrasound showed a mass or a thickened bladder wall, sometimes together with abnormal cells in the urine.

A normal urinalysis is useful information, but it does not rule out bladder cancer in this breed.

Lawn Chemicals: What the Evidence Shows

In a case-control study comparing 83 Scotties with bladder cancer to 83 Scotties with other conditions, the odds of cancer were higher in dogs exposed to lawns or gardens treated with both herbicides and insecticides (odds ratio 7.19) or with herbicides alone (odds ratio 3.62). Exposure to lawns treated only with insecticides was not significantly associated with increased risk. Lawns treated with phenoxy herbicides, the class that includes 2,4-D, which the authors discuss, were associated with increased risk (odds ratio 4.42), while non-phenoxy herbicides were not significantly associated (Glickman et al., 2004).

The authors were careful about what this does and does not prove. The study relied on owner recall and showed an association, not cause and effect. Their recommendation was that, until further studies resolved the question, Scottie owners should minimize their dogs' access to lawns or gardens treated with phenoxy herbicides (Glickman et al., 2004).

That is a low-cost precaution. It can mean not treating your own lawn with these products, keeping your dog off neighbors' treated lawns and public areas that have been recently sprayed, and asking any lawn service which products it uses.

What About Flea and Tick Products?

Older insecticidal dips were linked to bladder cancer risk in earlier research on dogs generally (Ackley, 2026). A companion Purdue study in Scotties examined topical flea and tick products and did not find an increased risk with the spot-on products then in use (Raghavan et al., 2004). That finding is reassuring for owners worried that routine parasite prevention is harming their dog, though it applies to the products studied at that time. Newer products should be discussed with your veterinarian rather than assumed to be covered.

Vegetables and Bladder Cancer Risk

The same research group compared the diets of 92 Scotties with bladder cancer and 83 Scotties without it. After adjusting for age, weight, neuter status, and coat color, Scotties that ate vegetables at least three times a week had about 70% lower odds of bladder cancer (odds ratio 0.30). Green leafy vegetables (odds ratio 0.12) and yellow-orange vegetables such as carrots (odds ratio 0.31) were each associated with lower odds. Cruciferous vegetables showed a similar trend that did not reach statistical significance, and the study did not have enough statistical power to evaluate vitamin supplements (Raghavan et al., 2005).

This is an observational finding in one breed. It does not prove vegetables prevent cancer, and dogs that ate more vegetables may have differed in other ways. Still, adding vegetables is inexpensive and low risk for most dogs. Ask your veterinarian which vegetables and amounts are appropriate for your individual Scottie, particularly if your dog has other health conditions or a special diet.

Screening: What the Purdue Study Found

The most important Scottie cancer research of recent years is the Purdue screening study. Scotties aged six and older with no urinary symptoms were screened every six months for three years with a physical exam including a rectal exam, a urinary tract ultrasound, and a urinalysis. Dogs with abnormal findings had a cystoscopic biopsy (Dhawan et al., 2022).

The findings:

• Cancer was confirmed in 32 of 120 dogs, 13 of them at the very first screening visit (Dhawan et al., 2022).
• Tumors found by screening were much smaller, with a median volume of 1.1 cubic centimeters, compared with 5.4 cubic centimeters in Scotties from earlier studies who were already having urinary problems (Dhawan et al., 2022).
• Dogs treated early with an oral anti-inflammatory drug from the COX inhibitor class had a 42% remission rate, compared with 17% to 25% for similar drugs used alone in dogs with more advanced cancer in earlier studies (Dhawan et al., 2022).
• Median overall survival in the early-treated dogs was 615 days (Dhawan et al., 2022).

That survival figure needs a caution the authors themselves gave. When cancer is found earlier, dogs will appear to live longer after diagnosis even if treatment changes nothing, simply because the clock started sooner. The researchers treated survival as an exploratory measure for exactly this reason (Dhawan et al., 2022). The remission rate comparison is more meaningful, though it compares against earlier studies rather than a randomized control group.

The screening was also done at a university with specialist ultrasound, following a standardized protocol. Whether and how often to screen your own dog, and with what tests, is a decision to make with your veterinarian.

The BRAF Urine Test: Useful, With Caveats

Most canine bladder cancers carry a mutation in a gene called BRAF, and a commercial urine test, the CADET BRAF Mutation Detection Assay, detects it in cells shed into the urine. According to MSPCA-Angell, the mutation is found in about 85% of these tumors, a positive result is more than 99% specific, and the test is not affected by blood or bacteria in the urine. A negative result does not rule out cancer, because around 15% of tumors lack the mutation and early tumors may shed too few cells to detect (Ackley, 2026).

The Purdue screening study adds an important complication. At the end of the study, banked urine from the symptom-free Scotties was tested with a droplet digital PCR assay for the same mutation, based on published methods. In that setting, the mutation was detected in 22 of 23 dogs with high-grade cancer, but also in 33 of 80 dogs in which no cancer or precancerous change was found during a median of 18 months of follow-up. The positive predictive value was only 44%, rising to 66% when a higher mutation threshold was applied (Dhawan et al., 2022). The authors called for more research into why the mutation appeared in dogs without detectable cancer.

The two sources describe different groups of dogs, and the screening study does not state whether its assay was identical to the commercial test, so the numbers cannot be compared directly. What they suggest together is that a BRAF result is one piece of evidence to interpret with your veterinarian, not a stand-alone answer, particularly in a dog without symptoms.

How Bladder Cancer Is Diagnosed

Ultrasound is commonly used to examine the bladder wall, kidneys, and ureters and to look for spread in the abdomen, but a definitive diagnosis requires a biopsy obtained by cystoscopy or surgery (Ackley, 2026). MSPCA-Angell also notes that blind needle collection of urine directly from the bladder carries a risk of seeding tumor cells along the needle track (Ackley, 2026). If your Scottie is being evaluated for a possible bladder mass, it is reasonable to ask how the urine sample will be collected.

Treatment

Treatment is often medical, because complete surgical removal is frequently not possible once the disease is advanced (Ackley, 2026). In the Purdue data comparing earlier studies, dogs with more advanced cancer treated first-line with a COX inhibitor alone had a median survival of about 243 days across breeds, and 310 days among Scotties (Dhawan et al., 2022). Chemotherapy drugs used in the screening study after COX inhibitor treatment stopped working included carboplatin, vinblastine, mitoxantrone, and chlorambucil (Dhawan et al., 2022).

Your veterinarian or a veterinary oncologist will tailor treatment to your dog's tumor, kidney function, and overall health. [INTERNAL LINK: bladder cancer treatment overview, when published] Because this cancer affects urination, quality of life often hinges on whether your dog can urinate comfortably. The Joys of Life Scale from the Drake Dog Cancer Foundation can help you track how the good days and hard days are balancing out.

Keeping a Record

With a cancer whose early signs look like everyday urinary problems, a written record is especially valuable. Note each episode of straining, accidents, blood, or increased urination, and every antibiotic course and whether signs came back afterward. The Dog Cancer Tracker (dogcancertracker.com) is one way to keep that history in one place, and it can make the pattern of recurring "infections" visible to your veterinary team.

When to Contact a Veterinarian

Seek emergency veterinary care immediately if your Scottie is straining to urinate but producing little or no urine. Advanced bladder cancer can obstruct urine flow (Ackley, 2026), and an inability to urinate is an emergency.

Schedule a prompt appointment if your Scottie shows:

• Blood in the urine, even once.
• Straining, discomfort, or taking longer to urinate.
• Urinating more often, or accidents in a previously house-trained dog.
• Urinary signs that return after a course of antibiotics.
• Abdominal discomfort, reduced appetite, or lethargy alongside any urinary change.

For Scotties aged six and older with no symptoms, ask your veterinarian at the next routine visit whether periodic bladder ultrasound makes sense.

Questions to Ask Your Veterinarian

• My Scottie has urinary signs. Given the breed, should we do a bladder ultrasound now rather than treating for infection first?
• If this is treated as an infection and the signs return, what is the next step?
• How will the urine sample be collected, and is there any concern about needle collection if a mass is possible?
• Would a BRAF urine test be useful for my dog, and how would we interpret a positive or negative result?
• Would periodic screening ultrasound make sense for my dog, and how often?
• Which vegetables, and how much, are safe to add to my dog's diet?
• Is the flea and tick product my dog uses one that has been studied for bladder cancer risk?
• If cancer is found, what are the treatment options, and would a referral to a veterinary oncologist help?

Sources

Ackley, D. V. (2026, March 2). A new approach to diagnosing transitional cell carcinoma in dogs. MSPCA-Angell. https://www.mspca.org/clinical/a-new-approach-to-diagnosing-transitional-cell-carcinoma-in-dogs/

Dhawan, D., Ramos-Vara, J. A., Utturkar, S. M., Ruple, A., Tersey, S. A., Nelson, J. B., Cooper, B. R., Heng, H. G., Ostrander, E. A., Parker, H. G., Hahn, N. M., Adams, L. G., Fulkerson, C. M., Childress, M. O., Bonney, P. L., Royce, C., Fourez, L. M., Enstrom, A. W., Ambrosius, L. A., . . . Knapp, D. W. (2022). Identification of a naturally-occurring canine model for early detection and intervention research in high grade urothelial carcinoma. Frontiers in Oncology, 12, Article 1011969. 

Glickman, L. T., Raghavan, M., Knapp, D. W., Bonney, P. L., & Dawson, M. H. (2004). Herbicide exposure and the risk of transitional cell carcinoma of the urinary bladder in Scottish Terriers. Journal of the American Veterinary Medical Association, 224(8), 1290-1297. 

Knapp, D. W., Ramos-Vara, J. A., Moore, G. E., Dhawan, D., Bonney, P. L., & Young, K. E. (2014). Urinary bladder cancer in dogs, a naturally occurring model for cancer biology and drug development. ILAR Journal, 55(1), 100-118. 

Raghavan, M., Knapp, D. W., Dawson, M. H., Bonney, P. L., & Glickman, L. T. (2004). Topical flea and tick pesticides and the risk of transitional cell carcinoma of the urinary bladder in Scottish Terriers. Journal of the American Veterinary Medical Association, 225(3), 389-394. 

Raghavan, M., Knapp, D. W., Bonney, P. L., Dawson, M. H., & Glickman, L. T. (2005). Evaluation of the effect of dietary vegetable consumption on reducing risk of transitional cell carcinoma of the urinary bladder in Scottish Terriers. Journal of the American Veterinary Medical Association, 227(1), 94-100.