Urinary Tract Infection

Urinary Tract Infection in Cats.


Bacterial infections of the bladder and kidneys are common in older cats but are almost always associated with an underlying condition - either diabetes or kidney disease. Because of these associated conditions, urinary tract infections in cats usually need to be treated with an effective antibiotic for at least six weeks.


Discussing urinary tract infections and cystitis in cats is confusing. This is because words are used differently by different people. This is a list of our use of the words. Be aware that other sources may use other definitions.

Cystitis: Inflammation of the urinary bladder regardless of cause.

Bacterial Cystitis: Inflammation of the urinary bladder due to bacterial infection.

Dysuria: Difficult or painful urination. This may manifest as squatting to urinate for long periods, making frequent trips to the litter box, urinating outside of the litter box, howling, or a number of other ways.

Stranguria: Straining to urinate. Since cats don't usually make a face or an odd noise when they strain, a lot of times humans don't recognize what they are doing to be straining.

House soiling: Urinating or defecating in the house, outside of the litter box. Some veterinarians use the term periuria or inappropriate urination.

Idiopathic: A medical condition with a cause that has not yet been established in the medical literature. 

iFLUTD, FIC, FUS; These are all initialisms that are used for idiopathic cystitis in cats. (iFLUTD=idiopathic feline lower urinary tract disease, FIC=feline idiopathic cystitis or feline interstitial cystitis, FUS=feline urologic syndrome.)

Hematuria: Blood in the urine. Sometimes the urine still looks yellow and the blood can only be detected microscopically or with chemical tests. Sometimes it looks like pure blood.

Crystaluria: Crystals in the urine. 

UTI: Urinary Tract Infection. Infection anywhere in the urinary tract including kidneys, ureters, bladder, or urethra. If it is in the bladder, it usually causes bladder inflammation (bacterial cystitis). If the infection is not in the bladder, there usually isn't cystitis.

Stress: Psychological stress. This is an internal reaction to usually external stimuli. Anything that causes a cat to become upset, including medicating them, can cause stress.

Bladder Stone: A concretion of minerals and other materials that forms within the bladder.

Urethral Spasm: Inappropriate and painful contraction of the muscle of the bladder / urethral sphincter. Urethral spasms can prevent a cat from being able to urinate or they may cause an unsteady or intermittent stream of urine.

Urinary Obstruction: Anything that obstructs a cat's urethra so that they can't urinate. This is sometimes a "plug" of debris (crystals, blood, etc.) and it is sometimes a urethral spasm. Urinary obstructions are life threatening.  

Causes of Bladder Infections Cats.

Bladder infections in cats are almost always due to a bacterial infection. Because cats normally have very concentrated urine and effective immune mechanisms, it is very rare for them to have a bladder infection unless there are underlying conditions that allow bacteria to grow.

Infection is a common cause of cystitis in cats with kidney disease or diabetes. Infection is rare in cats without one of these underlying diseases. Of young cats with cystitis who don't have kidney disease or diabetes, approximately 3% have an infection.  That means that about 97% of young, otherwise healthy, cats who are showing signs of dysuria (difficulty in urinating) don't have an infection and don't benefit from antibiotics. 

Our experience is that most young cats who have been diagnosed with a "UTI" actually had idiopathic cystitis that is not a true infection.

Signs of Bladder Infection

The signs of bladder infection are the same as the signs of other causes of cystitis in cats.


Humans with cystitis describe it as being very painful and we are confident that the same is true in cats. Cats show pain in a number of ways including hiding, not eating, and vocalizing. Frequently the signs of pain are subtle and humans don't know that their cat is in pain.

Frequent Urination:

With cystitis, the nerve endings in the bladder are stimulated, making it feel to the cat as though they have to urinate, even when the bladder is empty. Humans will see the cat squatting as though to urinate with nothing coming out. This is problematic in that the exact same thing is seen when a cat has a urinary obstruction. They squat to urinate and no urine comes out.

House Soiling:

For reasons that are variable and not fully understood, some cats will urinate outside the litter box when they have cystitis.

Complications of Bacterial Cystitis

Urinary Obstruction:

This is an uncommon complication in cats with a bacterial cystitis It is common in male cats with idiopathic cystitis and very uncommon in female cats. 

If your cat is squatting to urinate and no urine is coming out, you should consider it a life-threatening emergency. It cannot wait until morning.

Pain and Discomfort:

Cats with bacterial cystitis are in pain, even though it may not be obvious to people.

It is important to realize that if your cat is going in and out of the litter box, trying to urinate frequently with little success, they are in pain.

If an infection is localized to the kidneys, and not in the bladder, the cat will not have signs of bladder pain.

Treatments for Bacterial Cystitis

Treat underlying cause. Since bladder infection in cats is usually secondary to another problem, we always try to address the primary disease (usually diabetes or kidney disease).

Antibiotics. We usually recommend a culture to determine the best antibiotic to use and then treat with that antibiotic for a minimum of six weeks. 

Pain medication. We often recommend a narcotic to alleviate pain for the sake of relieving pain. 

Fluids. We sometimes recommend subcutaneous fluids. Since most cats with a bladder infection have diabetes or kidney disease, their urine is usually already dilute so this treatment is not as beneficial as it is in cats with idiopathic cystitis.

Antispasmodics.  We sometimes treat with drugs that can decrease urethral spasms. It is felt that this can help with some of the pain that cats experience.


It can be difficult to prevent a urinary tract infection in a cat.

If the infection is related to diabetes, we prevent recurrence by treating the diabetes.

If the infection is related to kidney disease, there is usually no good way to prevent further infections. The best we can do is look for infection before they cause significant clinical signs and then treat accordingly.

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