Urinary tract infection in dogs (bacterial cystitis)
Bacterial cystitis is an infection of the bladder. Bacteria from the skin and genital area travel up the urethra, the small channel that carries urine out of the body, and settle in the bladder. The bladder wall becomes irritated: the dog n...
What is it?
Bacterial cystitis is an infection of the bladder. Bacteria from the skin and genital area travel up the urethra, the small channel that carries urine out of the body, and settle in the bladder.
The bladder wall becomes irritated: the dog needs to urinate very frequently, passing only small amounts each time, straining or appearing uncomfortable, and blood may appear in the urine. The dog's overall condition usually remains good.
It occurs more often in females. A single infection responds well to treatment; a recurring infection warrants investigation into underlying causes that favor bacterial colonization.
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 urination, with only small amounts passed each time.
Straining to urinate, the dog remaining in position for a long time or appearing distressed.
Urine tinged with blood, appearing pink or red.
Small leaks of urine or urination indoors in a previously housetrained dog.
Frequent licking of the vulva or prepuce.
Appetite and energy levels usually remain normal; fever or lethargy suggest infection has spread to the kidney or prostate.
Some dogs show no signs: the infection is discovered during 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
The infection is caused by bacteria traveling from outside into the bladder; Escherichia coli, a bacterium present in the intestines, is the most common culprit.
Normally the bladder defends itself: urine flowing out flushes away bacteria, and the bladder wall prevents them from attaching. Cystitis develops when these defenses are weakened.
A recurring infection prompts investigation for an underlying cause: urinary stones, diabetes mellitus, Cushing's syndrome, prolonged corticosteroid therapy, incomplete bladder emptying, urine leakage, vulva sunken into skin folds, or a mass in the bladder.
Female: a shorter urethra facilitates bacterial ascension.
Diabetes mellitus, Cushing's syndrome, prolonged corticosteroid therapy.
Urinary calculi.
Incomplete bladder emptying, urine leakage, nerve damage.
Vulva sunken into skin folds, remaining damp.
Dog unable to go outside frequently enough to urinate.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The veterinarian examines the dog, palpates the bladder, and confirms that urination is normal.
Diagnosis is based on urine analysis. The ideal method is a sample collected directly from the bladder using a fine needle to avoid bacteria from the skin.
Urine culture identifies the bacteria and shows which antibiotics are effective; this is especially useful when the infection recurs.
If recurrence occurs, ultrasound or X-rays look for stones or a mass, and a blood test checks for diabetes or Cushing's syndrome.
In an intact male, the prostate is examined.
Treatment
Treatment is based on an antibiotic chosen by your veterinarian for the duration specified.
Do not use leftover antibiotics from home and do not stop treatment sooner than advised, even if signs have disappeared.
Pain relief medication may be prescribed for the first few days.
If recurrence occurs, treating the underlying cause is essential: stones, diabetes, Cushing's syndrome, or vulval abnormality.
Bacteria found in urine in a dog with no signs do not always warrant antibiotics: your veterinarian will decide.
A urine recheck may be requested after treatment.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Leave fresh water available to your dog at all times and take him outside frequently so he can empty his bladder.
If your female dog has a vulva that sits in a skin fold, keep the area clean and dry according to your veterinarian's instructions.
Have any diabetes or Cushing's syndrome monitored regularly.
Seek veterinary advice at the first signs: a urinary tract infection caught early is easier to treat.
Possible complications
Recurrence, especially when the underlying cause is not treated.
Kidney infection, with fever, lethargy, and pain in the flanks.
Prostate infection in an intact male.
Some bladder stones can develop as a result of infection.
Bacteria becoming resistant to antibiotics when treatments are repeated or not followed properly.
When to see a veterinarian
Your dog, especially if male, strains to urinate and nothing comes out: immediate emergency, the bladder may be blocked.
He has a fever, is lethargic, no longer eats, or seems to have pain in the back or flanks: consult the same day.
He urinates very frequently in small amounts or strains to urinate.
His urine is red or pink.
He urinates in the house despite being housetrained, or constantly licks his genitals.
Signs return after treatment.
Prognosis
A simple urinary tract infection generally heals well with appropriate treatment that is followed correctly.
Recurring urinary tract infections require finding and treating their cause; they can usually be controlled once the cause is addressed.
Frequently asked questions
Cystitis or Urinary Stones: How to Tell the Difference?
The signs are the same: frequent urges, straining, blood in the urine. Only urinalysis and imaging can tell the difference, and both conditions can coexist. Simple cystitis does not block urine flow: a male straining without passing anything suggests an impacted stone, which is an emergency.
My dog urinates frequently: is it necessarily an infection?
No. Frequent urination of very small amounts suggests a bladder problem: cystitis or stones. Urinating large amounts while drinking heavily points more toward diabetes, Cushing's syndrome, kidney disease, or in an unspayed bitch, pyometra. These situations require different tests.
Can I give him the antibiotic that worked well for him last time?
No. The bacterium is not necessarily the same; treatment must be chosen for this particular episode, and inadequate treatment promotes resistance. Recurrent cystitis should indeed be investigated, with a urinalysis and often a urine culture.
Can my dog's cystitis be transmitted to my family?
Bacterial cystitis in dogs is not considered a disease that spreads from animals to humans. Standard hygiene rules are sufficient: wash your hands after cleaning up its urine.
References
Content reviewed by the TunisieVet editorial team · Updated 11 October 2026
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