When to see a vet urgently
Seek veterinary attention promptly if urinary symptoms are accompanied by any of the following:
- Your cat strains but passes no urine or only drops.
- Your cat vomits, becomes weak or stops eating.
- Pain is severe or your cat's general condition deteriorates rapidly.
- Your cat collapses or cannot stay on its feet normally.
Particularly in a male cat, failure to pass urine may be caused by a life-threatening urethral blockage. You can find a vet near you.
Overview
Cystitis inflames the bladder wall, causing pain and frequent, painful urination. In cats, it often begins suddenly and appears as restless behaviour. Infection may remain confined to the bladder, but without treatment it can spread to the ureters and kidneys.
Bladder inflammation and bacterial infection do not mean the same thing. Lower urinary tract signs are common in cats, but bacteria are only one possible cause. Particularly in an otherwise healthy young adult, pain and blood in the urine may also be associated with idiopathic cystitis or urinary stones.
Conversely, bacteria can be found in urine without symptoms of a urinary tract infection. This is called asymptomatic, or subclinical, bacteriuria. Its significance and treatment needs differ from symptomatic bacterial cystitis. Diagnosis therefore combines the sample result with the cat's clinical situation.
Causes
Common causes of bacterial cystitis include:
- bacteria entering the bladder, such as Escherichia coli, Staphylococcus, Proteus and Enterococcus
- secondary infections associated with urinary stones
- weakened immune defences in older cats
- chronic kidney disease
- bladder catheterisation or surgery
- poor hygiene in animal care
Bacteria usually ascend through the urethra into the bladder. E. coli, for example, is an intestinal bacterium that can cause a urinary tract infection when it enters the urinary tract under suitable conditions. However, the finding alone does not reveal the source of exposure in an individual cat.
Predisposing factors may include unusually dilute urine, impaired bladder emptying or a structural change in the urinary tract. Diabetes and other underlying diseases are also considered. An infection should not automatically be attributed to poor owner hygiene or insufficient grooming by the cat.
Risk factors
- Cats over 8–10 years of age.
- Females, which have a shorter urethra.
- Animals with urinary stones or chronic kidney insufficiency.
- Overweight and inactive cats.
- Pets that have undergone urinary tract surgery.
Risk factor associations vary between bacterial inflammation and other lower urinary tract diseases, and cat-specific evidence for every item listed is limited. Being female and certain diseases can increase the likelihood of finding bacteria, but age or excess weight alone does not confirm diagnosis. The actual cause of symptoms is investigated even in an at-risk cat.
Symptoms
You may notice the following symptoms:
- frequent urges to urinate but little urine passed
- pain and straining during urination
- blood in the urine, called haematuria
- foul-smelling urine
- restlessness and meowing in the litter tray
- urine leakage or urinating outside the tray
- reduced appetite and activity
Urine smell or blood alone does not establish bacteria, and urinating outside the tray is not simply a behavioural habit. Your cat may have pain, urgency or difficulty reaching the tray. Some cats lick their genital area more than usual. Report these observations at the appointment.
Frequent small urinations are distinguished from producing more urine overall than usual. Large urine volumes and thirst may be associated with kidney disease or diabetes, for example. Leakage can also result from a problem either with storing urine or with emptying it normally. Your observations help select the necessary investigations.
Complications
Without treatment, bacterial cystitis can lead to:
- chronic bladder inflammation
- pyelonephritis, or kidney infection
- formation of stones and crystals
- declining kidney function
- significantly reduced quality of life
Not every infection causes stones, and not every urinary stone is caused by bacteria. However, certain bacteria can alter urine acidity and promote struvite crystal formation. Any link between a stone and inflammation is investigated because an antibiotic alone does not always remove a factor maintaining recurrence.
In pyelonephritis, inflammation is within the kidney tissue. Symptoms may include weakness, failure to eat, vomiting or other signs of systemic illness. Not every patient has fever or abdominal pain, so their absence does not rule out kidney infection. Impaired kidney function and bacteria in the urine then require broader assessment.
Diagnosis at the vet
Diagnosis is based on investigations including:
- a urine sample for routine analysis and bacterial culture
- ultrasound of the bladder and kidneys
- blood tests to assess kidney function
- X-rays where necessary
At the appointment, your vet establishes when symptoms began, previous urinary problems and antibiotic use, and any catheterisation or surgery. Also report changes in drinking and urine volume and other diseases. The examination assesses whether urine can pass normally and whether your cat has local pain or more extensive illness.
A culture sample is preferably obtained directly from the bladder with a needle, called cystocentesis. This reduces interpretation problems caused by bacteria entering the sample from outside. A sample collected from a litter tray or floor is not equivalent when assessing bacterial culture. Ask the clinic for sampling instructions before collecting urine at home.
Routine urine analysis assesses concentration, cells, blood, crystals and bacteria, among other things. The white blood cell pad on a urine dipstick alone is not reliable for diagnosing infection in a small animal. Other sediment in a sample can also be mistaken for bacteria, so sample handling and microscopic assessment are essential.
Culture and susceptibility testing help identify the bacterium and select an effective medicine. A positive result shows bacteria are present in the sample, but the distinction between asymptomatic bacteriuria and symptomatic infection is made clinically. If a sample is needed, the aim is to obtain it before starting antibiotics, following the clinic's plan.
Blood tests and imaging add to assessment, particularly in recurrent, severe or otherwise unusual cases. Ultrasound and X-rays can look for stones, bladder changes or another predisposing problem. An image alone does not identify bacteria, and urine acidity alone does not determine the cause of infection.
Treatment and antibiotic selection
Treatment of a symptomatic bacterial infection includes an antibiotic selected for the situation and pain relief where necessary. Medication may need to start before the final culture result, but the result can alter the choice. As well as the bacterium, infection location and your cat's other health conditions affect medicine suitability.
An infection of the bladder lining and one within kidney tissue are different treatment situations. A seriously ill patient may need hospital care and other supportive treatment. A medicine being excreted well into urine does not, by itself, determine treatment for every kidney tissue infection. Tell the treating vet about systemic symptoms and changes in kidney values.
Do not give antibiotics left from an earlier course or prescribed for another animal. Follow the instructions for this particular cat, and contact the clinic if administration is not possible or side effects occur. Avoiding unnecessary medication reduces the risks of adverse effects and selection of resistant bacteria.
Asymptomatic bacteriuria does not usually need an antibiotic. An underlying risk disease or bacterial resistance alone does not turn a symptom-free finding into symptomatic cystitis either. The treating vet assesses possible exceptions. Do not interpret a decision not to treat as equivalent to overlooking a painful infection.
Recurrence and monitoring
Monitor pain, litter tray visit frequency, urine output and general wellbeing. If symptoms fail to improve or return, contact the clinic for reassessment. The need for a follow-up sample is agreed separately according to symptoms, the original finding and treatment response.
A new bacterial episode may be a new infection or persistence of the previous one. Comparing culture results helps distinguish these situations. Recurrent problems prompt a search for a stone, bladder change, retained urine or another disease maintaining infection. Repeating the same antibiotic without investigating the cause can leave a predisposing factor untreated.
Support in the home environment
Keep water easily accessible and follow the agreed diet. Provide quiet, clean and sufficiently spacious litter trays. A tray must also be easy to reach for a cat with joint pain or mobility difficulties. A lower side may help an older cat step inside.
In a multi-cat home, position trays so another animal cannot block access. Avoid strong fragrances around the tray and retain litter your cat accepts. A positive litter tray experience supports normal urination, but environmental measures alone do not eliminate a confirmed bacterial infection.
Prevention
Cystitis can be prevented through:
- always providing clean drinking water and good-quality food
- regular litter tray cleaning
- avoiding excess weight and inactivity
- prompt treatment of urinary stones
- regular veterinary visits to monitor urinary tract health
Prevention targets identified predisposing factors. Stone disease and bacterial infection do not always need the same diet or monitoring. Do not add products that change urine acidity on your own initiative: factors other than bacteria also affect urine pH. The cause of new painful urination is assessed even if a previous episode was bacterial.
This text provides general information and does not replace veterinary care. Contact a vet if your cat develops symptoms.
Frequently asked questions
Does blood in the urine always mean bacterial infection?
No. Idiopathic cystitis, stones and other urinary diseases can also cause blood and pain. Identifying the cause guides treatment.
Does a bacterial finding without symptoms need an antibiotic?
Usually not. The significance of asymptomatic bacteriuria is assessed separately, and a positive culture alone does not establish symptomatic infection.
Is urine collected from a litter tray suitable for culture?
It may contain external bacteria, making interpretation difficult. For culture, your vet usually prefers a sample taken directly from the bladder. Ask for sampling instructions beforehand.
Why do symptoms need investigating again if they return?
The cause may be persistence of the previous infection, a new bacterium or an entirely different urinary disease. Reassessment also helps identify possible stones or other predisposing factors.
This article is for general information only and is not a guide to treatment. If you notice the first signs of illness, contact your vet.
Paw4care editorial team
Sources
- Bacterial Cystitis in Small Animals, Merck Veterinary Manual, accessed 2026-11-03.
- Urinary Tract Infections in Cats, VCA Animal Hospitals, accessed 2026-11-03.
- Diagnostic testing, American Animal Hospital Association, accessed 2026-11-03.
- Overview of Infectious Diseases of the Urinary System in Small Animals, Merck Veterinary Manual, accessed 2026-11-03.
- Pyelonephritis in Small Animals, Merck Veterinary Manual, accessed 2026-11-03.
- Feline Lower Urinary Tract Disease, Cornell Feline Health Centre, accessed 2026-11-03.
- Litter Boxes, The Ohio State University, Indoor Pet Initiative, accessed 2026-11-03.