Ketone Strips for Cat Urine: What They Detect and When to Use

Name: Ketone Strips for Cat Urine: What They Detect and When to Use
Creator: Dr. Zubair Khalid

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-10-03

Cat urine ketone strips are small plastic dipsticks that change color when ketones are present in your cat's urine. They are a useful at-home screening tool for owners of diabetic cats, and they can help you decide whether a cat needs to be seen right away. This article is educational and is not a substitute for veterinary diagnosis or treatment.

Quick Answer

Ketones are byproducts of fat burning. High levels in a diabetic cat can signal diabetic ketoacidosis, a medical emergency.
You can collect urine at home with a clean, non-absorbent litter or a collection tray, then dip the strip and read it at the exact time printed on the bottle.
A negative or trace result on a well cat is usually not concerning. A moderate or large positive result means call your veterinarian now, or go to an emergency clinic.
Home strips are a screening tool, not a diagnosis. Your veterinarian confirms results with a urinalysis and blood tests [1].
Some collection litters can interfere with dipstick readings for ketones and glucose, so use them only for rough screening [2].

What Are Cat Urine Ketone Strips and What Do They Detect?

Ketone strips are reagent pads on a plastic stick. When you dip the pad in urine, a chemical reaction causes a color change. The color is compared to a chart on the bottle to estimate how much ketone is present.

The strips most owners buy detect acetoacetate, one of the three ketone bodies the body makes when it burns fat for energy instead of glucose. The other two are beta-hydroxybutyrate and acetone. This matters because blood ketone meters, which some owners use, measure beta-hydroxybutyrate instead. The two tests do not always agree, so a urine strip and a blood meter can give you different pictures on the same day.

Ketones show up in urine when the body cannot use glucose properly and starts breaking down fat quickly. In cats, the most common reason is poorly controlled diabetes. Ketones can also appear with prolonged poor appetite, severe illness, or starvation, but diabetes is the situation where home testing matters most.

Why Owners Test at Home

For a diabetic cat, urine ketone testing is a way to catch a problem between veterinary visits. If your cat's insulin dose is too low, if an infection is brewing, or if your cat has stopped eating, ketones can rise before you notice other signs. Catching that early gives you time to call your veterinarian instead of rushing to an emergency room.

Ketone testing is not the same as glucose testing. Urine glucose tells you what blood sugar was doing hours ago. Urine ketones tell you whether the body is in a metabolic crisis mode. Both can be useful, but ketones are the more urgent number.

If your cat is drinking and urinating more than usual, that is often the first sign of a diabetic problem. You can read more about that pattern in Cat Urinating a Lot and Drinking a Lot: Causes and When to Test.

How to Test Cat Urine Ketones at Home

Gather Your Supplies

You need fresh ketone strips, a way to collect urine, and good lighting. Check the expiration date on the bottle. Expired strips can give false results. Keep the bottle closed between uses, because moisture and air degrade the pads.

For collection, you have a few options:

Non-absorbent litter. Special plastic beads or specially designed collection litter let urine pool at the bottom of the box. These are practical, but they can affect some dipstick results. In one study, ketone and glucose readings were inconsistent after urine sat in polypropylene-based collection litter, and sediment samples were more contaminated [2]. Use this method for screening, not for a result you plan to act on alone.
A clean, empty litter box. Some cats will urinate in a bare box, especially if you place it where their normal box sits. This gives you the cleanest sample.
A ladle or shallow cup. Slide it under your cat while she urinates. This takes timing and a calm cat.
Plastic wrap over the litter. Some owners lay a sheet of plastic over the litter so urine pools on top. Remove it right after your cat finishes.

Avoid clumping clay litter for collection. It absorbs urine and contaminates the sample.

Dip and Read the Strip

Follow the instructions on your strip bottle exactly. The timing matters. Most strips require you to dip the pad briefly, shake off excess urine, then wait a set number of seconds before reading the color. Reading too early or too late gives a wrong result.

Read the pad under bright white light, not a colored bulb. Compare the pad to the chart on the bottle. Write down the result and the time you tested. If you are unsure about a color, ask your veterinarian to show you a chart at your next visit, or bring the strip with you.

Visual reading of dipsticks varies between people. In one study, agreement between experienced and inexperienced observers on dipstick results was only fair for several parameters, though agreement was better for some measurements than others [3]. That is a polite way of saying two people can look at the same strip and see different colors. When in doubt, treat a borderline result as a reason to call your vet.

Keep a Simple Log

Write down the date, time, result, and anything unusual that day, such as a skipped meal or a dose of insulin given late. This log is genuinely useful to your veterinarian. Patterns matter more than a single reading.

What a Positive Result Means

The strip chart usually runs from negative to trace, small, moderate, and large. The exact labels depend on the brand.

Negative. No ketones detected. Keep testing on the schedule your veterinarian recommends.
Trace. A faint reaction. This can happen with mild appetite loss or a minor insulin shortfall. Call your veterinarian for advice, especially if your cat is not eating well or seems off.
Small. Ketones are present. Call your veterinarian the same day. Your cat may need a dose adjustment, a check for infection, or a recheck of blood work.
Moderate or large. This is an emergency. Diabetic ketoacidosis can develop quickly and becomes life threatening. Go to a veterinary emergency clinic now, even if your cat seems alert.

Do not wait for your cat to look sick before acting on a moderate or large result. Cats hide illness well, and ketoacidosis can progress over hours.

What Diabetic Ketoacidosis Looks Like

Warning signs include vomiting, not eating, weakness, wobbling, heavy or rapid breathing, a fruity or acetone smell on the breath, and lethargy. Some cats become dehydrated and collapse. If you see these signs along with a positive ketone strip, treat it as an emergency.

Recovery Timeline and Home Care

If your cat is treated for high ketones or ketoacidosis, the hospital stay and home recovery follow a general pattern. Your veterinarian sets the actual plan based on your cat's condition.

Timeframe	What Usually Happens
First 24 to 48 hours	Hospital care with intravenous fluids, insulin, and frequent blood and urine monitoring. Your cat may stay overnight.
Days 2 to 4	Ketones should be falling. Your cat may start eating again. Insulin dosing is adjusted based on test results.
First week at home	Recheck visit with blood work. You resume home urine testing. Feed the prescribed diet on a consistent schedule.
Weeks 2 to 4	Insulin dose is often fine tuned. Ketone strips may be needed daily or a few times a week, depending on your vet's plan.
Ongoing	Regular monitoring for the rest of your cat's life. Some cats need testing more often during illness or diet changes.

At home, keep meals and insulin on a steady schedule. Stress and skipped meals both raise the risk of ketones. If your cat refuses food, call your veterinarian the same day instead of waiting.

If your cat has other urinary signs, such as straining or peeing outside the box, those may be separate problems. Blood in the urine is a different red flag and is covered in Cat Peeing Blood: What Should You Do?. Peeing on the bed can be medical or behavioral, and the difference matters, as explained in Cat Peeing on the Bed: Medical or Behavioral?.

Possible Complications and Warning Signs

The main complication is missing ketoacidosis until it is advanced. Home strips help, but they are not perfect. A cat can have rising blood ketones before urine ketones climb, and collection litter can blur the reading [2].

Other issues to know about:

False negatives. Expired strips, poor storage, or a dilute sample can hide ketones.
False positives or confusing colors. Some medications and some sample conditions can affect dipstick pads. Your veterinarian can sort this out with a proper urinalysis [1].
Interference from litter. Ketone and glucose results were inconsistent in samples exposed to polypropylene collection litter [2].
Reader error. People reading the same strip do not always agree on the color [3].

Call your veterinarian the same day if your cat has a small ketone reading, is eating less, or has had a recent insulin change. Go to an emergency clinic now if you see moderate or large ketones, repeated vomiting, weakness, trouble breathing, or a cat who will not eat at all.

Questions to Ask Your Veterinarian

Bring these to your next visit or ask them by phone:

How often should I test my cat's urine for ketones?
Which strip brand and reading method do you recommend for my cat?
What result should make me call you, and what result means I should go to the emergency clinic?
Should I also track urine glucose, or is ketone testing enough for my cat?
What should I do if my cat will not eat or I cannot collect a sample?
How do I adjust testing when my cat is sick or on a new insulin dose?

Limitations and When to Contact a Veterinarian

Home ketone strips are a screening tool. They cannot tell you why ketones are present, and they cannot replace a urinalysis, blood glucose testing, or a physical exam [1]. Dipstick testing in general has real limits, and results vary between observers and methods [3]. Even glucose testing by dipstick, which is a related technology, has imperfect sensitivity in cats [4].

Contact your veterinarian the same day if:

Your cat has a small ketone reading.
Your cat is eating less than usual or has vomited once or twice.
You missed an insulin dose or gave it late.
Your cat seems tired or is hiding more than usual.

Go to an emergency clinic now if:

Ketones read moderate or large.
Your cat is vomiting repeatedly or cannot keep water down.
Your cat is weak, wobbly, breathing fast, or unresponsive.
Your cat has not eaten for more than 24 hours.
You cannot get a urine sample and your cat looks unwell.

Schedule a routine visit if your cat is stable but you want to review your home testing routine, your log, or your cat's diet. Diet changes can affect glucose and ketone patterns, and your veterinarian can help you choose the right food. General information on urinary diets is available in Cat Urinary Tract Diet.

Every cat is different. Your veterinarian needs to examine your cat and review test results to decide what is right for your pet.

Frequently Asked Questions

Can I use human ketone strips on my cat?

Yes, many owners use human urine ketone strips because the reagent pads detect the same ketone, acetoacetate, in cat urine. Check with your veterinarian about the brand and read the bottle instructions carefully, since timing and color charts differ between products.

What causes ketones in a cat's urine besides diabetes?

Prolonged not eating, severe illness, and starvation can all raise ketones. In a diabetic cat, the most common cause is not enough insulin or a stress event like infection. Your veterinarian can sort out the cause with blood work and a urinalysis [1].

How do I collect urine from a cat who will not use a bare box?

Try non-absorbent collection litter, a ladle, or plastic wrap over the litter. Keep in mind that collection litter can affect ketone and glucose readings, so treat those results as a rough screen [2]. If you cannot collect a sample and your cat seems sick, call your veterinarian instead of waiting.

Do I need to fast my cat before testing urine ketones?

No. Urine ketone testing does not require fasting, and fasting a diabetic cat is dangerous. Test when you can catch a fresh sample, and keep your cat on her normal feeding and insulin schedule unless your veterinarian says otherwise.

How accurate are home urine ketone strips?

They are useful for screening but not perfect. Reading the color can vary between people, and agreement between observers on dipstick results is only fair for some parameters [3]. Collection litter can also make ketone results inconsistent [2]. Use the strip to guide your next step, not to make a diagnosis.

References

Detecting Disorders of the Kidneys and Urinary Tract of Cats - Cat Owners. Merck Veterinary Manual.
Evaluating the impact of polypropylene-based cat litter on urinalysis reliability in feline patients. Polish journal of veterinary sciences, 2025.
Assessment of inter-observer agreement among experienced and inexperienced observers and an automated device for dipstick urinalysis in dogs and cats. Journal of veterinary diagnostic investigation : official publication of the American Association of Veterinary Laboratory Diagnosticians, Inc, 2023.
Accuracy of urine dipstick tests and urine glucose-to-creatinine ratios for assessment of glucosuria in dogs and cats. Journal of the American Veterinary Medical Association, 2020.