By The Pawline veterinary teamVeterinary-reviewed by Alastair Greenway, BVM&S MRCVS · 25 July 2026
A urinalysis is three tests in one — concentration, a chemical dipstick, and microscopic sediment — and it transforms the meaning of blood results. Without a urine sample, kidney blood markers can only ever be half-interpreted, which is why a urinalysis is the most under-requested test in veterinary medicine.
Blood tests tell you what is circulating; urine tells you what the kidneys are doing about it. That is why a urinalysis so often changes the meaning of a blood result — and why running kidney bloods without urine is, in a real sense, working with half the information.
A urinalysis is three tests in one — concentration, chemistry, and microscopic sediment — and it transforms how blood results are read.
A complete urinalysis has three parts, and each answers a different question.
1. Concentration (specific gravity)
Urine specific gravity measures how concentrated the urine is — how well the kidneys conserve water. This is the part that most often reframes the bloods: a raised creatinine with concentrated urine suggests dehydration, while the same creatinine with dilute urine points at the kidneys themselves. It is measured with a refractometer, not the dipstick (the dipstick's gravity pad is unreliable in animals).
2. The chemical dipstick
The dipstick pads screen for several things at once. In pets, some are genuinely useful and others should be ignored:
Protein — useful as a screen, but must be interpreted against concentration and confirmed with a UPC, which is the real quantitative test.
Glucose — should be absent. Its presence suggests either diabetes (blood glucose exceeding what the kidneys can reabsorb) or, less commonly, a kidney tubular disorder.
Ketones — should be absent; their presence with glucose points to diabetic ketoacidosis, an emergency.
Blood — flags bleeding or, sometimes, muscle pigment; the sediment then distinguishes them.
pH — relevant to crystal formation and some metabolic states.
Bilirubin — small amounts can be normal in dogs (especially concentrated urine); in cats any bilirubin in urine is abnormal and significant.
Leukocytes and nitrite pads — unreliable in dogs and cats and should not be used. Infection is judged on sediment and culture.
3. The sediment (the microscope)
Spinning the sample and examining the deposit is where much of the diagnostic value lives:
White blood cells — inflammation, and with bacteria, suggest infection.
Red blood cells — bleeding anywhere along the urinary tract.
Bacteria — suggestive of infection, but culture is the definitive test, since sediment can mislead in both directions.
Casts — cylindrical moulds formed in the kidney tubules; their presence points specifically at kidney (rather than bladder) disease.
Crystals — struvite, calcium oxalate and others. Important caveat: crystals can form in the sample after collection, especially if refrigerated or left standing, so crystals on a stale sample may mean nothing. They are also not the same thing as stones.
Cells — abnormal epithelial cells occasionally raise the question of urinary tract cancer.
Why collection matters so much
How the sample is obtained changes what the results mean. A cystocentesis sample (taken directly from the bladder with a needle) is the gold standard for culture because it avoids contamination; a free-catch sample inevitably collects some debris and bacteria from the lower tract and skin. And because crystals precipitate and cells degrade with time, a fresh sample analysed promptly is far more reliable than one that has sat for hours.
Cat vs dog
Both species get the same three-part analysis, with two notable differences. Cats normally produce very concentrated urine, so a dilute feline sample is a more striking finding. And urinary signs in cats — straining, blood, frequent trips to the tray — often reflect feline idiopathic cystitis (a stress-associated, sterile inflammation) rather than infection, which is comparatively uncommon in young cats; in dogs, bacterial cystitis is a far more likely explanation for the same signs.
About the reference range
This page shows no range strip — a urinalysis is a panel of qualitative and quantitative findings rather than one number with a band. Individual quantitative components have their own pages (USG, UPC). Read each finding against the reference on your own report.
What to do next
If your pet is having kidney or urinary blood tests, ask whether a urine sample can be collected at the same time — it frequently changes the interpretation. Where infection is suspected, ask about a cystocentesis sample for culture rather than relying on sediment alone. And treat dipstick protein as a screen to be confirmed with a UPC, not an answer in itself.
This page is educational and is not a diagnosis. Lab results are interpreted in the full clinical context by your veterinary surgeon; a single value rarely tells the whole story.
