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Canine Bladder Infections

  • A bladder infection occurs when microbes (usually bacteria) get into the bladder and proliferate.
  • Bladder infections are more common in females than in males; however, any dog can have a bladder infection.
  • Frequent squatting or straining without producing much urine is the most common sign of bladder infection.
  • Treatment for the infection includes a course of antibiotics.
  • Bladder stones must be removed through surgery, broken up by sound waves, or eliminated using a special diet.

What Is a Bladder Infection?

The bladder is an expandable sac, like a balloon, that lies toward the back of the abdomen and is part of the system that removes waste from the body. 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 microbes (usually bacteria) travel up the urethra and proliferate, causing an infection. These bacteria may come 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.  

What Are the Signs of a Bladder Infection?

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 frequently pass small amounts of urine that are often tinged with blood. Constant squatting and straining without passing much urine and having urinary accidents in the house are typical signs of potential bladder infection. Bladder infections are more common in females than in males; however, any dog can have a bladder 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 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!

How Is a Bladder Infection Diagnosed?

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 radiography (x-rays) or ultrasound imaging is sometimes needed to look for stones, tumors, or other abnormalities involving the bladder.

How Are Bladder Infections Treated?

Treatment for a simple bladder infection usually consists of 1 or 2 weeks of antibiotics. Chronic or severe infections may require longer treatment. Infections that clear up and then come back 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 inserted through the urethra to crush the stones using sound waves and flush out the resulting stone fragments. This is a specialized procedure that may require referral to a specialty practice.
  • Your veterinarian may recommend a specialized, prescription diet that changes the chemical makeup of the urine and causes the stones to dissolve. This is the least invasive technique, but it takes more time and commitment and is not effective for all bladder stones. Specialized, prescription diets are also used to help prevent bladder stone recurrence in pets.