A cat's urine can be screened at home in about 20 minutes with a strip that costs under $1. Four values carry most of the information: specific gravity, glucose, protein, and blood. The strip is the easy part. The hard parts are getting a sample less than 30 minutes old from a cat who resents your interest in the box, and reading the pads without falling for the false positives that make healthy cats look sick.
Why urine shows trouble before behavior does
Kidney disease and diabetes both leave traces in urine weeks before a cat looks unwell. A cat with chronic kidney disease (CKD) loses concentrating ability first, so urine stays pale and voluminous while blood creatinine is still inside the reference range. Glucose appears in urine only after blood glucose passes roughly 250 mg/dL, the renal threshold, which makes a positive glucose pad late but hard to argue with. Losing 300 g over 2 months while eating normally is usually when owners start looking; the strip would have flagged it 4 to 6 weeks earlier.
Three collection methods that actually work
- Bare box. Wash and dry the box, leave it empty, and wait. Most cats use it within 10 to 20 minutes of a meal or a long drink. Pour the sample off and test it. Highest success rate, zero contamination, but a stubborn cat may hold urine for 12 hours rather than step on plastic.
- Non-absorbing litter. Plastic beads, glass beads, or the hydrophobic pellets sold for sampling. Two centimeters deep, box in its usual corner, checked every 15 minutes. Rinse and dry the beads between uses; the same batch lasts years.
- Pad or cling film. Line a clean box with an absorbent pad or plastic wrap. Fast and cheap, worst to read: fibers and plasticizers lift the protein and blood pads. Keep it as the fallback when the first two fail.
The 30-minute rule
Bacteria double roughly every 20 to 30 minutes at room temperature. Inside an hour a sample can drift alkaline, dissolve struvite crystals that were genuinely there, and eat the glucose, turning a true positive into a clean negative. Test within 30 minutes of collection. If that is impossible, refrigerate at 2 to 8 C for no more than 2 hours and note the delay, because cold storage precipitates some crystals and nudges specific gravity upward.
The four readings that fool people
Protein. The pad is pH sensitive. Urine above pH 8, common in a sample that sat out or came from a cat just fed a high-protein meal, reads trace to 1+ with no disease at all. Re-test a fresh sample; if protein is 1+ or more at pH 6.5 to 7.0, ask for a urine protein-to-creatinine ratio (UPC). Under 0.2 is normal, above 0.4 is a conversation.
Blood. Litter dust, bleach residue, and oxidized cleaners all trip the hemoglobin pad. A genuinely bloody sample usually looks pink and comes from a cat who has been straining.
Glucose. Peroxide and chlorine give a false positive; bacteria give a false negative. Confirm with a blood glucose meter before you believe either.
Leukocyte. Validated on human urine and unreliable in cats. Ignore this pad entirely. A cat with a bladder infection may show only a rising pH and a few crystals.
Specific gravity: the number to track
Specific gravity says how concentrated the urine is, and in cats it is the most informative single value on the strip. On dry food a healthy cat runs 1.035 to 1.060. On wet or raw food, 1.020 to 1.035 is normal because the food is already 75 to 80 percent water. Below 1.020 on repeated samples is dilute and needs a reason: CKD, diabetes, hyperthyroidism, or infection. Above 1.060 points to dehydration, common in winter and in cats who barely drink. A flat 1.008 to 1.012 across 3 samples is the classic signature of lost concentrating ability, and it earns bloodwork within a week.
Reading the pads
| Strip value | Normal for a cat | What a deviation suggests |
|---|---|---|
| Specific gravity | 1.035-1.060 on dry food; 1.020-1.035 on wet | Low and fixed: CKD, diabetes, thyroid. High: dehydration |
| pH | 6.0-6.5 on meat-based food | Above 7.0 favors struvite; below 6.0 favors calcium oxalate |
| Protein | Negative to trace | 1+ or more on a fresh sample: request a UPC ratio |
| Glucose | Negative | Positive means blood glucose near or above 250 mg/dL |
| Blood | Negative | Positive with straining: cystitis, stones, or blockage |
| Ketones | Negative | Positive in a diabetic cat: call the clinic today |
| Bilirubin | Negative | Any positive in a cat is abnormal; liver or red-cell workup |
When it has to go to a laboratory
Send the sample the same day for protein at 1+ or more, glucose at any level, ketones, bilirubin, unexplained blood, or specific gravity under 1.020. A lab adds sediment examination, which is the only way crystals, casts, and cells get identified; a strip cannot see any of them. Go in immediately, not tomorrow, if a male cat makes repeated unproductive trips to the box, cries while urinating, or has passed no urine in 12 hours. Urethral obstruction can kill within 24 to 48 hours. The full set of signs is in urinary blockage signs.
A 20-minute routine, once a month
- Collect on a morning after wet food; urine usually arrives within 30 minutes.
- Test immediately, before coffee, not after.
- Write specific gravity, pH, and any positive pad into a phone note with the date.
- Repeat on 2 consecutive mornings before drawing conclusions from one dirty strip.
- Photograph the strip beside the note and take the picture to the next exam.
Run it monthly for any cat over 8, and every 3 months for a cat already diagnosed with CKD or diabetes, because the trend beats any single result. What the blood side of the picture looks like is covered in kidney disease early signs and diabetes in cats.
Frequently asked
Can I use the litter my cat already uses to collect a sample?
No. Clumping clay absorbs the urine within seconds and contaminates it with dust that trips the blood and protein pads. Use a washed, dried, empty box, non-absorbing beads, or a pad, and test within 30 minutes of collection so bacteria do not change the pH and dissolve any crystals.
What urine specific gravity is normal for a cat?
Between 1.035 and 1.060 on dry food, and 1.020 to 1.035 on wet or raw food, because those diets are already 75 to 80 percent water. Repeated readings below 1.020, or a flat 1.008 to 1.012 across three samples, mean the kidney has lost concentrating ability and deserves bloodwork within a week.
The strip says protein but the cat seems fine. What now?
Re-test a fresh sample first. Protein pads react to pH, so urine above pH 8 or a sample left standing can read trace to 1+ with no disease present. If protein stays at 1+ or higher on a fresh sample at pH 6.5 to 7.0, ask the vet for a urine protein-to-creatinine ratio, where under 0.2 is normal.