A usable urine sample is 3 to 5 mL in a clean container, delivered within 30 minutes, and read against a specific gravity of 1.035 or higher for a well-concentrated cat. There are 3 ways to get one: non-absorbent litter, a midstream catch, or cystocentesis at the clinic. Pick by what the sample is for, because a culture needs a sterile draw and a screening dipstick does not.
Method 1: non-absorbent litter
Empty the box, wash it, dry it, then add 250 to 400 g of a litter that will not soak up liquid: washed aquarium gravel at 3 to 5 mm, commercial hydrophobic plastic beads, or plain unprinted newspaper pellets. Put the box back in its usual corner and wait. Most cats use it within 4 hours; a nervous cat may hold for 12, so do not stand and watch.
When the cat leaves, draw the pool up with a syringe or a pipette within 5 minutes and push it into a sterile screw-cap tube. A 3 mL draw is enough for a dipstick, a specific gravity reading and a sediment exam. Gravel leaves no fibers and no dust, which is why it beats plastic wrap stretched over the box: wrap tears, and shredded paper changes the color reading.
Method 2: midstream catch
Use a shallow foil tray, a clean ladle or a flat plastic lid, and slide it under the cat as soon as the tail lifts, not after the first drops land. Let the first 1 to 2 mL go, because that volume carries the urethral flush, then catch 3 to 5 mL from midstream. A litter box with 1 cm of litter can also be tilted so the urine runs to one corner and pools instead of soaking in.
This method is the fastest and the least stressful, and it is clean enough for a dipstick, a specific gravity reading and a sediment review. It is not clean enough for a bacterial culture, because hair, perineal skin and box residue all add organisms that will grow in the dish and mean nothing.
Method 3: cystocentesis at the clinic
A vet passes a fine needle through the abdominal wall into the bladder under ultrasound or by palpation, and pulls 5 to 10 mL. It takes 2 to 3 minutes, needs no sedation in most cats, and is the only route that gives a sterile sample. Ask for it when the question is a urinary infection, when a culture has already been run on a free-catch sample, or when the cat is a male with a history of blockage.
| Method | Typical volume | Contamination risk | Time cost | Good for |
|---|---|---|---|---|
| Non-absorbent litter | 3 to 8 mL | Low to moderate | 4 to 12 hours of waiting | USG, dipstick, sediment |
| Midstream catch | 2 to 5 mL | Moderate | 5 to 30 minutes | USG, dipstick, screening |
| Cystocentesis | 5 to 10 mL | None, sterile | 10 to 15 minutes at the clinic | Culture, resistant cases |
| Expression by hand | 1 to 3 mL | High | 2 to 5 minutes | Rarely acceptable |
| Catheter | 5 to 10 mL | Low | 15 to 20 minutes | Blocked males, hospital only |
Manual expression is on the list only so you can rule it out. Pressing a bladder raises pressure against a possibly obstructed urethra and can rupture it, and the sample is usually blood-tinged enough to ruin the red cell count.
Read the specific gravity first
A healthy cat on wet food usually lands at 1.035 to 1.050, and a cat on dry food can reach 1.060. Below 1.035 means the kidney is losing concentrating ability or the cat is drinking more than usual; 1.008 to 1.012 is isosthenuria, where urine is no more concentrated than plasma, and that single number is worth a full panel. A cat at 1.020 with a creatinine of 90 micromol per liter is not necessarily sick, but the pair should be repeated in 4 to 6 weeks rather than filed away.
Then read the rest of the strip, the part the home urine testing guide breaks down pad by pad: pH 6.0 to 6.5 in most cats, protein negative to trace, glucose negative, ketones negative, blood negative, bilirubin negative to trace. On sediment, more than 5 white cells per high-power field or more than 5 red cells suggests inflammation; struvite crystals are common at pH 7.0 and above, calcium oxalate at pH 6.0 and below. Bacteria seen on a free-catch slide is a maybe; bacteria on a sterile sample is a fact.
The 30-minute clock
Bacteria in urine double every 20 to 30 minutes at room temperature, so a sample left on a counter for 3 hours can read as an infection that is not there. Deliver within 30 minutes, or refrigerate at 2 to 8 Celsius and bring it in within 12 hours. Refrigeration preserves chemistry and specific gravity well and harms cells a little, so note the time of collection on the tube, not the time you get to the clinic.
Volume matters here too. 3 mL lets the lab run a strip, a USG and a spin; 1 mL is a strip only. If you only get 2 drops, do not drive 40 minutes with it: call and ask whether to try again tomorrow morning, when urine is most concentrated.
When home collection is the wrong move
- A male cat that has produced no urine for 12 hours, or is squatting with nothing coming out, needs the clinic now, not a sample.
- Visible blood, straining for more than 10 minutes, or crying in the box is a same-day visit.
- 3 failed attempts in 24 hours means stop trying and book a cystocentesis.
- A cat that stops eating, vomits twice, or hides after a failed attempt should be examined rather than sampled.
Do this in the next 7 days
- Buy 3 sterile screw-cap tubes and a 5 mL syringe before you need them.
- Wash 400 g of 3 to 5 mm gravel and keep it in a lidded jar as your sampling litter.
- Collect the morning sample, when specific gravity runs highest.
- Write the collection time on the tube and photograph the dipstick beside it.
- Book the urine culture in advance if the cat has had 2 or more episodes in 12 months.
Keep the strip photo with the date: 3 samples across 6 months at 1.045, 1.030 and 1.018 tell a story that any single result hides, and the trend is often visible weeks before creatinine moves.
Terms mentioned in this article
Frequently asked
Can I use a normal clumping litter and squeeze the clump?
No. Clumping litter binds liquid into a solid mass, and what you squeeze out is a slurry of clay dust, scent and bacterial load that clogs the strip and shifts the specific gravity reading. Use 250 to 400 g of washed 3 to 5 mm gravel, or ask the clinic for non-absorbent beads.
How long can a sample sit in the fridge?
Chemistry and specific gravity survive 12 hours at 2 to 8 Celsius, cells degrade faster. A sample for culture should reach the lab within 30 minutes, because bacteria double every 20 to 30 minutes at room temperature and a delay can turn a negative into a false positive. Write the collection time on the tube.
My cat's USG came back 1.020. Is that kidney disease?
Not by itself. 1.020 is dilute for a cat, and it can follow a wet diet, a busy morning, or a diuretic. Pair it with creatinine, SDMA and phosphorus, then repeat in 4 to 6 weeks on a morning sample. A single 1.020 with normal values is a reason to retest, not a diagnosis.