Urinary Tract Infections (UTIs) in Cats

By Courtney Barnes, BSc, DVM; Malcolm Weir, DVM, MSc, MPH; Robin Downing, DVM, DAAPM, DACVSMR, CVPP, CRPP

My cat suddenly began using the litterbox very frequently. A sample of urine revealed a bladder infection. How did this happen?

While urinary tract disorders are common in cats, urinary tract infections (UTIs) are fairly uncommon. Cats with UTIs try to urinate frequently, may pass only small amounts of urine, may strain to urinate, and may cry or whine when urinating. Sometimes, blood may be visible in their urine. Urinating outside the litterbox is also a red flag that something is wrong in the bladder. Finally, frequent licking around the rear end may signal that a UTI is present.

Generally, a UTI occurs when bacteria travel up the urethra (the tube through which urine exits the body) and into the bladder. Urine in the bladder is sterile, but once bacteria find their way there, they can grow and reproduce, causing a UTI. Additionally, some cats will develop bladder stones with or without a UTI, which opens the door for additional health issues.

What does a urinalysis look at?

If your cat presents to your veterinarian with urinary signs, your veterinarian will first perform a urinalysis. There are several urinary tract disorders that can mimic the signs of a UTI, so it is important to do this test. The urinalysis reveals important information about the urine. Your veterinarian will look for the following:

  • urine-specific gravity (how well the cat is concentrating their urine)
  • pH (certain pH levels can indicate infection or other problems)
  • ketones (sometimes seen in cases of diabetes or body-wasting)
  • glucose (sugar in the urine, usually a sign of diabetes)
  • bilirubin (a breakdown product of blood)
  • blood
  • protein

Once these levels are measured, the urine specimen is “spun down” in a machine called a centrifuge to allow cells and other debris to accumulate at the bottom of the sample tube. That debris can then be evaluated under a microscope. This examination can reveal the presence of red blood cells, white blood cells, bacteria, and crystals.

What is seen under the microscope can lead to the next steps in assessing your cat’s urinary tract disease. For example, if there are crystals in the urine, your veterinarian may recommend X-rays or an ultrasound of the abdomen to look for bladder stones.

My veterinarian sent a urine sample to a laboratory for a culture and sensitivity test. What is this test?

All urinary tract infections are different. The most common organism to cause UTIs in cats is Escherichia coli (a bacteria found in feces), but there are many other possibilities. Sometimes there is more than one type of bacteria involved in the infection. The only way to identify which bacteria is involved is to grow it in a laboratory. At the same time, the lab can also test which antibiotic is best suited to treat the infection.

"The only way to identify which bacteria is involved is to grow it in a laboratory."

Often, a veterinarian will prescribe an antibiotic that should be effective against most common bacteria (first line drug) to try to provide immediate relief to the cat. Pain medication may also be prescribed, as UTIs can be uncomfortable, and a diet change may be recommended.

Once the culture and sensitivity results are received, your veterinarian may change the antibiotic if a more appropriate medication is identified. After the course of antibiotics is completed, it is important to recheck the urinalysis to confirm that the infection is resolved. If it is not, then it is important to investigate additional issues that may contribute to a persistent UTI.

If the infection is not treated, your cat will experience ongoing discomfort. Complications can also occur, such as bladder stones or a kidney infection called pyelonephritis.

Are some cats predisposed to UTIs?

Female cats are more prone to UTIs than male cats due to their smaller, wider urethras. Older female cats are more highly represented among cats with UTIs.

Certain medical conditions can predispose a cat to UTIs, including diabetes mellitus (sugar diabetes), kidney disease, hyperthyroidism, bladder cancer, and immunosuppression. Cats with bladder stones are also more prone to recurrent UTIs. The variety of underlying causes of UTIs highlights the importance of getting a complete diagnosis whenever there is evidence of disease in the urinary tract. Bladder stones must be removed or dissolved to restore bladder health.

Certain anatomic issues can also predispose a cat to UTIs, such as ectopic ureters. Obesity can also play a role, as overweight cats cannot groom well, and the skin folding around the genitals traps moisture and bacteria.

If predisposing factors are not addressed, UTIs can become difficult to resolve and may be a recurring problem.

What can I do to prevent a UTI from occurring in the future?

Your veterinarian will inform you if anything can be done to prevent your cat’s UTI from recurring. There is evidence that specific diets can support health of the lower urinary tract. It is best to discuss UTI prevention and bladder health with your veterinarian to enact an effective plan.

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