Bacterial urinary tract infection (cystitis) in cats
Bacterial cystitis is an infection of the bladder caused by bacteria, usually intestinal bacteria that travel up through the urethra, the tube that carries urine out of the body. Contrary to common belief, it is uncommon in young, healthy c...
What is it?
Bacterial cystitis is an infection of the bladder caused by bacteria, usually intestinal bacteria that travel up through the urethra, the tube that carries urine out of the body.
Contrary to common belief, it is uncommon in young, healthy cats: in them, urinary problems are usually non-infectious in origin, such as idiopathic cystitis. Infection becomes more frequent in older cats, from around ten years of age onward, and in cats with a disease that makes urine more dilute or weakens their defenses: kidney disease, diabetes, or hyperthyroidism.
Its signs resemble those of other bladder diseases: only a urinalysis with culture can confirm the infection.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
Related signs — each one links to its page:
Frequent trips to the litter box, passing only small amounts of urine each time.
Straining to urinate, with the cat remaining in a crouched position for extended periods.
Pink or red-tinged urine, or blood traces in the litter box.
Urine passed outside the litter box, often on smooth surfaces or fabrics.
Involuntary urine leakage, with drops left where the cat was lying.
Persistent licking of the genital area.
In older cats, the infection can go unnoticed, with no visible signs, and may only be discovered during a urinalysis.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
Bacteria, usually from the intestines, travel up the urethra and establish themselves in the bladder.
Normally, concentrated urine, complete bladder emptying, and natural defenses prevent this colonization.
Infection occurs when these protective mechanisms are weakened: dilute urine (kidney disease, diabetes, hyperthyroidism), incomplete bladder emptying, presence of calculi, urinary catheterization or urethral surgery, or treatments that reduce immunity.
Older cats, from around ten years of age onward.
Chronic kidney disease, diabetes, or hyperthyroidism.
Poor bladder emptying: incontinence, nerve damage, urine retention.
Urinary calculi.
Recent urinary catheterization or urethral surgery in males.
Treatment with corticosteroids or other causes of weakened immunity.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The veterinarian first checks that the bladder is not blocked, particularly in males.
He palpates the abdomen and analyzes a urine sample, ideally collected directly from the bladder using a fine needle passed through the abdominal wall: this quick and minimally painful procedure prevents contamination of the sample.
Urine culture confirms the infection, identifies the bacteria, and reveals which antibiotics are effective against it.
Ultrasound or radiographs are used to detect bladder stones or abnormalities.
Blood work is performed to identify any underlying disease, such as kidney disease or diabetes.
Treatment
The infection is treated with an antibiotic chosen by your veterinarian, preferably based on the urine culture results.
The antibiotic must be given in full for the prescribed duration, even if signs disappear quickly.
For recurring infections, a new culture is performed during or after treatment to confirm that the infection has cleared.
Any underlying disease is managed in parallel: poorly controlled diabetes or kidney disease perpetuates relapses.
Bacteria found in the urine of a cat with no signs generally do not require antibiotic treatment: your veterinarian will decide.
Never use leftover antibiotics from a previous treatment: this promotes antibiotic-resistant bacteria.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Encourage your cat to drink: offer wet food, multiple water bowls, and a water fountain if he enjoys it.
Keep the litter box clean and easily accessible, particularly for an older or arthritic cat.
Arrange regular checkups for senior cats, diabetic cats, or those with kidney disease; a urine analysis is often part of this monitoring.
Consult your veterinarian at the first signs of urinary problems rather than waiting for them to resolve on their own.
Possible complications
Spread of infection to the kidneys (pyelonephritis), causing fever, lethargy, and back pain.
Recurrent infections, especially if the underlying disease is not well controlled.
Development of antibiotic-resistant bacteria following repeated or incomplete treatments.
In males, inflammation that can lead to urethral blockage, which is a life-threatening emergency.
When to see a veterinarian
Your male cat strains in the litter box with no urine passed: seek immediate emergency care, as urinary blockage may be present.
Your cat has fever, is lethargic, vomits, or shows signs of back pain: consult within the day, as the infection may have reached the kidneys.
He uses the litter box very frequently to pass small amounts of urine or shows signs of straining to urinate.
You see blood in his urine.
He urinates outside his box or dribbles urine.
Your senior cat, diabetic cat, or cat with kidney disease shows any of these signs.
Prognosis
A simple bacterial bladder infection generally heals well with appropriate and complete treatment.
Recurrent infections are more difficult to treat; the prognosis then depends mainly on the underlying disease and whether it can be controlled.
Frequently asked questions
How can it be distinguished from idiopathic cystitis?
The signs are identical: frequent urination, straining, blood in the urine, urination outside the litter box. Idiopathic cystitis mainly affects adult cats under ten years old, often in a context of stress, and their urine contains no bacteria. Bacterial cystitis is more common in older cats or those with kidney disease, diabetes, or hyperthyroidism. Only urine culture can determine which one it is.
What if they were calculations?
Urinary calculi produce the same signs and may coexist with infection. They are visible on radiography or ultrasound: this is why the veterinarian often recommends imaging in addition to urine analysis, especially when symptoms recur.
Why perform a urine culture rather than giving an antibiotic directly?
Because most urinary disorders in cats are not infectious, and unnecessary antibiotics do not relieve them. Culture confirms the infection and indicates which antibiotic will be effective against the causative bacterium, thereby limiting treatment failures and resistance.
My cat is straining but nothing comes out: could it be a urinary tract infection?
Not necessarily, and this is not the time to look for it. In a male, straining without results often indicates a urethral blockage, a life-threatening emergency that needs immediate veterinary attention. Any infection, if present, will be investigated afterward.
References
Content reviewed by the TunisieVet editorial team · Updated 11 October 2026
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