A bladder infection occurs when microbes (usually bacteria) get into the bladder and proliferate. Any dog can get a bladder infection, though females are more likely to get one. Because the disease irritates the organ, it increases the pet’s urge to urinate. Frequent squatting or straining without a lot of results is the biggest sign a pet has a bladder infection. Urine might also be cloudy or tinged with blood. Bladder infections can even lead to bladder stones (and vice versa). Treatment for the infection includes a course of antibiotics. If stones occur they must be removed through surgery, broken up by sounds waves, or eliminated via a special diet.


The bladder is an expandable sac, like a balloon, that lies toward the back of the abdomen. Urine flows from the kidneys, through the tube-shaped ureters, and into the bladder, where it is stored before being eliminated from the body through a tube called the urethra.

Urine in the bladder is normally sterile unless bacteria travel up the urethra and cause an infection. Bacteria may be introduced from the nearby rectal area or from the genital tract. Conditions such as diabetes can increase the risk of developing bladder infections, as can medications that depress the immune system, including high-dose or long-term corticosteroids.

In long-standing infections, the bladder tissue can thicken and scar, creating more places for bacteria to grow. Long-term infection also increases the chances that infection will spread upstream to the kidneys or cause bladder stones to form.

Symptoms and Identification

Urinary infections irritate the walls of the bladder, so pets with bladder infections have the urge to go even when there is little urine present. They will frequently pass small amounts of urine, often tinged with blood. Constant squatting and straining without passing much urine, or having urinary accidents in the house are typical indicators of potential urinary tract infection.

Bladder infections change the chemical makeup of the urine, which makes it easier for minerals in the urine to crystallize and form stones. Bladder stones add to the irritation and create places for bacteria to hide from bodily defenses and antibiotics.

On some occasions, bladder stones can also block the outflow of urine, which is a serious emergency situation. Pets with urinary obstruction can have a swollen, painful abdomen and strain repeatedly without passing urine. This is a medical emergency!

Your veterinarian can usually diagnose an uncomplicated bladder infection based on your pet’s history and a urinalysis. In some cases, a urine sample might be sent to a laboratory to determine the specific bacteria involved (through a culture and sensitivity test) as well as an effective antibiotic for treatment. Abdominal X-rays or ultrasound imaging are sometimes needed to look for stones, tumors, or other abnormalities involving the bladder.


Treatment for a simple bladder infection usually consists of a week or two of antibiotics. Chronic or severe infections may require longer treatment. Infections that clear up and then recur may suggest an underlying problem requiring additional diagnostic testing and treatment.

If bladder stones are present, there are several options for eliminating them:

  • A veterinarian can perform surgery to open the bladder and remove the stones.
  • A veterinarian can use a sterile probe routed up the urethra to crush the stones using sound waves and then flush out the pulverized crystals. This is a specialized procedure that may require referral to a specialty practice.
  • You can feed your pet a specialized, prescription diet that changes the chemical makeup of the urine and causes the stones dissolve. This is the least invasive technique but takes more time and commitment and is not effective for all bladder stones.
  • Specialized, prescription diets are also used to help prevent recurrence in pets prone to bladder stone formation.

This article was reviewed by a Veterinarian.