Pet Urinary Tract Infections: Causes and Treatments
Drs. Foster & Smith Educational Staff

Urinary Tract Infections

When a pet is diagnosed with a urinary tract infection, owners often ask: What are the causes? Will it happen again?

The urinary tract in dogs and cats includes the kidneys, ureters, bladder and urethra. Kidneys remove waste materials from the blood, forming urine. Urine moves from the kidneys into the ureters and is collected in the bladder. When the animal urinates, urine leaves the body through the urethra.

Although kidneys can become infected, the term urinary tract infection (UTI) is most commonly used to refer to a simple bacterial infection of the urinary bladder. Normal urine in the bladder is sterile – it does not contain any microorganisms, so if bacteria make their way up through the urethra and into the bladder, problems occur.

How UTI's Develop
During self grooming, an animal may transfer fecal bacteria from the anal area to the opening of the vulva or prepuce, which then may move into the urethra. Most of the time, bacteria is washed back out of the urethra with urination. If not, it can enter the bladder, causing irritation so the animal feels an almost constant urge to urinate. One of the most common signs of a UTI in pets is frequent urination.

Which Pets are Susceptible?
Many dogs and cats will develop a UTI at least once during their lifetime. Puppies seem to be especially prone because they lick frequently or because their immune system, which helps fight infection is still immature. Females are more susceptible to UTIs than males, due to anatomy. The male urethra is long and narrow, while the female urethra is short and wide. It is much easier for bacteria to travel the short length of the female urethra to reach the bladder. In contrast, the long, narrow male urethra is more easily blocked due to inflammation and debris. This blockage of urine flow is called a urethral obstruction, and it is particularly common in male cats. A urethral obstruction is extremely painful and is an emergency situation: if the obstruction is not quickly relieved, it can lead to death.

In most cases, a UTI is a simple bacterial infection that can be successfully treated with appropriate antibiotics. Often the animal will live the rest of its life without developing another UTI. However, if the animal continues to develop urinary tract infections, then further investigation is needed to discover the cause.