FrançaisDifferent situations, different meanings
- Sporadic bacterial cystitis: an occasional bladder infection in an otherwise healthy animal [1, 2].
- Recurrent cystitis: repeated infections; in the 2011 guidelines, 3 or more episodes in 12 months. Vets then look for an underlying cause [2].
- Pyelonephritis: infection that has reached the kidneys, a more serious situation [1].
- Subclinical bacteriuria: bacteria grow in the urine, but the animal has no signs. Treatment is generally not recommended [2, 3].
What the urinalysis shows
The sediment is examined under the microscope. Fewer than 5 white cells per high-power field is commonly accepted as normal, and up to 5 red cells is acceptable; a needle sample from the bladder can itself add a few red cells [4]. White cells and bacteria together support an infection, but the sediment alone is not enough to diagnose it [2]. See the urinalysis guide.
- Abbreviation WBC or leukocytes in the urine sediment section of the report.
- Result 20–30 per field in this illustrative line: clearly increased (pyuria).
- Unit /HPF: per high-power microscope field. Results are often given as a range.
- Laboratory interval Fewer than 5 per field is commonly accepted as normal [4].
- Flag H: above the interval. Points to inflammation; a culture tells whether bacteria are the cause [2].
Urine culture: the confirming test
- Sample: cystocentesis is preferred; free-catch urine should not be used for culture [2, 3].
- Handling: the urine is refrigerated and cultured within 24 hours [2, 3].
- Reading: the culture counts colonies (CFU/mL). From a cystocentesis sample, an infection typically gives at least 1,000 CFU/mL; higher thresholds apply to catheter and free-catch samples [2, 3].
- Sensitivity test: shows which antibiotics work on the bacteria found [1].
In cats, think idiopathic cystitis first
Bacterial infection causes fewer than 3% of lower urinary signs in otherwise healthy adult cats, but it is more common in older cats and cats with kidney disease [5]. Idiopathic cystitis (FIC) is the most common cause; the signs usually settle in 2 to 7 days but often come back [5]. In a study of 77 European cats with urinary signs, 57% had idiopathic cystitis, 22% stones, 10% urethral plugs and 8% an infection [6].
Male cats can develop a blocked urethra, which is life-threatening: high potassium is the most dangerous complication [5]. Owners may mistake straining in the litter box for constipation [5]. See potassium in dogs and cats.
Related articles
En français : l’infection urinaire du chat et du chien.
Questions to ask your veterinarian
- Was the urine sample taken by cystocentesis?
- Does the sediment show white cells and bacteria?
- Should we run a urine culture and sensitivity test?
- If infections keep coming back, what underlying cause should we look for?
- For my cat: could this be idiopathic cystitis or stones rather than an infection?
Get your pet’s urinalysis explained, line by line.
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Frequently asked questions
How do vets diagnose a UTI in dogs?
With the signs, a urinalysis and, ideally, a urine culture from a sample taken directly from the bladder [2, 3].
Do bacteria in the urine always need treatment?
No. Bacteria without signs (subclinical bacteriuria) generally do not need treatment, with some exceptions your vet will assess [2, 3].
Do cats get UTIs often?
Not when they are young and healthy: infection causes fewer than 3% of urinary signs in these cats. It is more common in older cats and cats with kidney disease [5].
What are the early signs of a UTI?
Peeing often and in small amounts, straining, blood in the urine, accidents in the house, or licking the genital area.
Why does my vet want a needle sample of urine?
A sample taken straight from the bladder is not contaminated by skin bacteria, so the culture result can be trusted [2].
Sources
- Weese JS et al. International Society for Companion Animal Infectious Diseases (ISCAID) guidelines for the diagnosis and management of bacterial urinary tract infections in dogs and cats. Vet J. 2019;247:8-25. doi.org/10.1016/j.tvjl.2019.02.008
- Weese JS et al. Antimicrobial use guidelines for treatment of urinary tract disease in dogs and cats. Vet Med Int. 2011;2011:263768. doi.org/10.4061/2011/263768
- Dorsch R et al. Urinary tract infection and subclinical bacteriuria in cats: a clinical update. J Feline Med Surg. 2019;21(11):1023-1038. doi.org/10.1177/1098612X19880435
- eClinPath, Cornell University College of Veterinary Medicine. Urinalysis: cellular constituents. eclinpath.com/urinalysis/cellular-constituents
- Taylor S et al. 2025 iCatCare consensus guidelines on the diagnosis and management of lower urinary tract diseases in cats. J Feline Med Surg. 2025;27(2):1098612X241309176. doi.org/10.1177/1098612X241309176
- Gerber B et al. Evaluation of clinical signs and causes of lower urinary tract disease in European cats. J Small Anim Pract. 2005;46(12):571-577. doi.org/10.1111/j.1748-5827.2005.tb00288.x
Laboratory methods and reference intervals vary. This article explains; it does not diagnose. For a decision about your pet, use the original report and talk to your veterinarian. Our editorial policy.