Although only about one to two percent of all cancers reported in dogs are bladder cancer, this type of cancer is potentially life threatening and is often very difficult to diagnose, especially at the early stages when treatment would be most effective. The most common type of bladder cancer in dogs is transitional cell carcinoma and the exact method of the development of this type of cancer is unknown. Females are more commonly found with bladder cancer and spayed females have a slightly higher risk than intact females, which is the opposite of most types of canine cancers. The breeds most commonly found with bladder cancer include the West Highland White, Shetland Sheepdog, Wirehaired Fox Terriers, Beagles and Scottish Terriers.
There are several theories as to why this type of cancer is more problematic in females than males, and many researchers believe that since male's urinate more frequently than females, there is less build up of carcinogens in the bladder, resulting in a decrease in the likelihood of developing transitional cell carcinoma. This would seem to be a logical assumption as the cancer is most commonly found on the inner lining of the bladder and in the urethra where urine is most commonly present. There are fewer incidents of tumors or cancerous cells in the muscles of the bladder or in the other parts of the urinary tract. There is also clear linkage of the development of the cancer to exposure to carcinogens in the environment such as insecticides and pesticides as well as the old flea dip solutions that used to be popular. Since this same type of cancer is also found in humans that smoke, there may be some link between second hand smoke and the chance of a dog developing bladder cancer.
The signs and symptoms of bladder cancer tend to mimic many other diseases and conditions that affect the kidneys and bladder. Blood test are needed to rule out other possible diseases and infections that may be causing the same type of symptoms. The most common symptoms owners will notice are a lethargic and inactive dog, frequent urination of very small amounts, often with blood present, straining to urinate or defecate, inability to exercise or increased coughing and wheezing when exercising. While these signs may also be present with a urinary tract infection antibiotics will not treat the condition and the dog will progressively become worse.
The only way to determine if bladder cancer is present is for the vet to do a biopsy and look for cancerous cells. A fiberoptic scope is inserted up the urinary tract into the bladder and a very minute tissue sample is taken for examination. In addition other body organs are also checked through x-rays and other ultrasound to ensure that the cancer is localized only in the bladder. Depending on the size of the tumor and the other test results treatment may be a surgical removal of the tumor or radiation treatments. Radiation treatment is usually very successful, however there are further complications from the treatment that may impeded bladder functioning and ultimately pose other severe health risks. Drug therapies have also been used with mixed results. Typically they are most effective when the tumor is small, in the early stages, and there is no spread of the cancer to other organs, tissues or bones.