Q: My dog keeps having urinary tract infections, and our vet wants to do a biopsy to see if the cause may be transitional cell carcinoma. What can you tell me about this disease?

A: Invasive TCC is a rare disease overall, but it's the most common cancer of the urinary tract in dogs. Certain breeds are at higher risk: Scottish terriers, Shetland sheepdogs, beagles, West Highland white terriers and wirehaired fox terriers.

We don't know exactly what causes the disease, but researchers suspect a combination of genetic predisposition and environmental factors, including exposure to lawns treated with herbicides and insecticides. At highest risk are obese female dogs.

Symptoms can mimic those of urinary tract infections: blood in the urine, straining to urinate and frequently recurring urinary tract infections. The disease is diagnosed through a tissue biopsy, obtained with a fiber-optic scope inserted into the bladder.

If the tissue sample is determined to be cancerous, your veterinarian or the oncologist (cancer specialist) can follow up with radiographs (X-rays), ultrasound or a CT scan to determine the location and size of the tumor and whether the disease has spread to other areas of the body.

If possible, the tumor is removed surgically. Otherwise, chemotherapy drugs and cox inhibitors may help to shrink it or prevent it from growing. With treatment, dogs have a good chance of living two years or more.