Bladder Infections and Stones
Bladder infections are common in both dogs and cats. The urinary bladder is a sac-like organ for storing urine. It is found within the abdomen in the area between the rear legs. When the muscles in the bladder wall contract, the urine then flows through the urethra, which is the narrow tube that carries the urine outside the body. A ring or "donut" of muscle called a sphincter surrounds the urethra near the bladder, closing off the flow of urine until it's time to go.
Normally, urine is sterile, which means that it doesn't contain any bacteria or other microorganisms. However, bacteria can sometimes travel up the urethra into the bladder, causing an infection. Infection leads to irritation, which causes the muscles in the bladder wall to spasm and an urge to urinate more often than usual. Pets with a bladder infection typically strain to urinate frequently, often passing only a small amount of cloudy or bloody urine. If you pet needs to urinate more frequently than usual or starts having accidents, these are signals to see your veterinarian for evaluation and treatment.
In some bladder infections, minerals in the urine crystallize and form bladder stones, which can be as small as grains of sand or larger than marbles or small rocks. Stones can also create areas where bacteria can hide from antibiotics, leading to long-term infections that are difficult to treat. Your veterinarian may be able to feel stones by palpating the bladder (ie, feeling it through the abdominal wall), but an x-ray or ultrasound is usually needed for a definite diagnosis. In some cases, the stones can be dissolved by feeding your pet a special diet that changes the mineral content of the urine. In other cases, your pet may need surgery to remove the stones or treatment with sonic vibrations that "crushes" the stones.
What causes a bladder infection?
Usually bacteria travel up the urethra to the bladder, where they multiply and cause pain and inflammation.
Do all dogs and cats get bladder infections?
Any dog or cat can get a bladder infection, but they are most common in females. Female animals have a shorter urinary tract and a weaker sphincter muscle, which makes it easier for bacteria to work their way up the tract.
Can bladder infections lead to more serious problems?
Bladder infections can cause crystals or stones, which can obstruct urinary outflow and make infections more difficult to treat. Urinary obstruction is especially a problem in male cats, and these animals should be seen by a vet immediately when showing signs of pain or straining during urination.