Feline lower urinary tract disease (FLUTD) is the umbrella name for problems that affect a cat's bladder and urethra, the tube that carries urine out of the body. You see it in the litter box: straining, lots of small pees, pink or red urine, or peeing somewhere else. The most common cause is feline idiopathic cystitis, a painful, stress-linked bladder condition, but stones, plugs and, less often, infection look exactly the same from the outside. So every cat with these signs needs a vet to find out which one it is.
One situation is always an emergency.
If your cat keeps squatting in the litter box and little or nothing comes out, get to a vet or emergency clinic now. Male cats are most at risk, because their urethra can plug up completely. Other warning signs: crying while straining, licking under the tail, vomiting, refusing food or hiding. Many owners think the cat is constipated. A completely blocked cat can die in less than 24 to 48 hours according to the Cornell Feline Health Center, or within 2 to 3 days according to International Cat Care. Don't wait until morning.
What Is FLUTD?
FLUTD describes what a cat is going through, not why. The 2025 consensus guidelines from International Cat Care (iCatCare) say it outright: "FLUTD" is not a diagnosis and doesn't name a cause. Your vet's job is to find the cause underneath, because that decides the treatment.
You may also see the older term feline urologic syndrome (FUS), which meant roughly the same thing. Feline idiopathic cystitis (FIC) is not another name for FLUTD. It is one cause, the most common one.
FLUTD can happen at any age. FIC is most common in young to middle-aged adult cats, while infections and some other causes get more likely as cats age.
Signs of FLUTD in Cats
Whatever the cause, an irritated bladder and urethra show it in the same few ways:
- Straining to urinate, often mistaken for straining to poop
- Frequent or long attempts to urinate
- Small amounts: drops or coin-sized puddles
- Discolored urine: red, pink or brown from blood
- Peeing in odd places, like the sink, the bathtub or right in front of you
- Crying out while urinating
- Overgrooming the genital area or belly
- Behavior changes: irritability, hiding or lethargy
A cat who suddenly pees on the bath mat isn't being spiteful. Pain teaches cats to avoid the box, and scolding only adds stress, which feeds the most common cause.
Is It a Blockage? Why Male Cats Are at Risk
Male cats have a long, narrow urethra, and that is where things get stuck. Cornell notes that male and neutered male cats are at greater risk of obstruction than females for this reason, and iCatCare says urethral obstruction happens almost exclusively in males. Females can block too, but it's rare because their urethra is wider.
Three things can block the urethra:
- A urethral plug: a soft, toothpaste-like mix of protein, inflammatory cells and crystals
- A small stone that has moved down from the bladder
- Swelling or spasm of the urethra itself
With the exit closed, urine has nowhere to go. Waste the kidneys would normally clear builds up in the blood, potassium climbs high enough to upset the heart rhythm, and the overstretched bladder can rupture. iCatCare says that after about 24 hours of blockage, cats get sick all over: vomiting, not eating, weak and lethargic.
Watch out for the constipation mix-up. A blocked cat hunched in the litter box looks just like a constipated one, and the iCatCare guidelines specifically warn about it. Our guide to cat constipation says the same from the other side: if you can't tell, assume it's the bladder and call.
What Causes FLUTD?
When vets work up cats with urinary signs, the iCatCare guidelines summarize what they find like this:
- Feline idiopathic cystitis (FIC): about 55-65% of cases
- Urinary stones: about 10-23% of cases
- Bacterial infection: under 3% in otherwise healthy adult cats
- Everything else (urethral plugs, bladder tumors, injuries, birth defects): uncommon
Merck puts it in one line: most cats with lower urinary tract signs have FIC.
Feline idiopathic cystitis (FIC)
"Idiopathic" means the vet looked for a cause and didn't find one. The pain is real even when the urine tests come back clean. In cats with FIC the bladder seems to react to stress, so flare-ups often follow a change at home: a new pet, building work, visitors or tension between cats. Our cystitis in cats guide covers FIC in depth, from why it flares to the full home plan.
Urinary stones (urolithiasis)
Stones are hard clumps of minerals, from sand-like grit to pebbles. They irritate the bladder lining and can slip into the urethra and block it. In cats, struvite (magnesium ammonium phosphate) and calcium oxalate make up about 90% of stones, according to iCatCare.
Crystals in a urine sample don't always match the stone a cat actually has. Only a lab analysis of the stone tells you its type for sure, and that matters because the two main types are treated differently.
Urethral plugs
Plugs are mostly a male-cat problem. They're softer than stones, made of protein, cells and crystals, and FIC itself can trigger them. That's one reason a cat with FIC can go on to block.
Bacterial infection (UTI)
A urinary tract infection is one possible cause of FLUTD signs, not another word for FLUTD. It's uncommon in healthy young and middle-aged cats. Infections are more likely in cats over 10, in females, and in cats with kidney disease, diabetes or an overactive thyroid. That's why antibiotics only belong in the plan when an infection is found or strongly suspected.
Other causes
Bladder tumors, injuries and birth defects can also cause urinary signs. They're uncommon, but they're part of why a senior cat with new urinary signs needs a fresh workup, even if the same cat had FIC years ago.
Risk factors
Cornell and iCatCare link these to a higher chance of FLUTD, and of FIC in particular:
- Being overweight and not very active
- Living indoors with little to do, or with limited outdoor access
- A mostly dry diet and low water intake
- Sharing the house with other cats, especially ones that don't get along
- A nervous personality, frequent diet changes or upheaval like a move
- Being male (for blockages, and for FIC in most studies)
How Vets Diagnose FLUTD
Since FLUTD is a description, the visit is about narrowing down the cause. Expect some or all of these:
- Your story. When it started, what changed at home, what your cat eats and whether it has happened before. Jot it down before the visit.
- Feeling the belly. A bladder that is big, hard and painful points to a blockage.
- A urine test (urinalysis) for blood, crystals, bacteria and how concentrated the urine is. Vets often draw urine straight from the bladder with a fine needle (cystocentesis). If you're asked to bring a sample, here's how to get a urine sample from a cat.
- A urine culture when infection is on the list, so the right antibiotic can be chosen.
- X-rays or ultrasound to look for stones, plugs or masses in the bladder.
- Blood tests, especially for older and blocked cats, to check the kidneys and electrolytes and look for diabetes or an overactive thyroid.
If none of that turns up a stone, an infection or a mass, the diagnosis is FIC.
Treatment Depends on the Cause
There's no single FLUTD treatment. Your veterinarian chooses every medicine and dose based on what the tests show.
If your cat is blocked
A blocked cat is stabilized first. Then, under sedation or anesthesia, the vet passes a thin catheter into the urethra to clear the blockage and empty the bladder. IV fluids bring potassium back down and rehydrate the cat, and pain relief is part of it. In severe cases the catheter stays in for a few days while the cat recovers in hospital, and Cornell puts typical stays anywhere from a few days to several weeks.
For a cat that keeps blocking, a surgery called perineal urethrostomy can widen the opening. Cornell treats it as a last resort.
If it's FIC
Pain relief is strongly recommended because FIC hurts, and your vet picks the drug. Most of the rest happens at home: less stress, more water and litter boxes your cat likes. iCatCare notes that antibiotics don't help without an infection.
If it's stones
It hinges on the type. Struvite stones can often be dissolved with a prescription diet your vet chooses. Calcium oxalate won't dissolve on any diet, so it has to be flushed out or surgically removed. Skip over-the-counter acidifiers and supplements: Cornell cautions that pushing urine too acidic creates new problems.
If it's an infection
The antibiotic is chosen from the urine culture results, so it matches the bacteria. Your vet will tell you if a recheck is needed.
Long-Term Care Your Vet May Set Up
Once the emergency or flare is over, the aim is fewer and milder episodes. Talk through which of these fit your cat before you change anything.
- More water. Dilute urine is the goal. iCatCare says a wet diet and more water may help prevent repeat episodes, though studies aren't conclusive. Extra bowls in different rooms and a fountain help some cats drink more. Cornell suggests small, frequent meals. Change food gradually, and don't mix other foods into a prescribed stone diet without asking.
- Less stress. For FIC, iCatCare calls environmental changes (MEMO) the standard of care: perches, hiding places, daily play and separate resources for each cat. Our cystitis guide, linked above, walks through it room by room.
- Good litter boxes. At least one more box than you have cats, in quiet spots away from food and water, with a litter your cat likes, kept clean. Switch litter gradually if you switch at all.
- Weight and play. Your vet can plan safe weight loss; wand toys, puzzle feeders and a safe outdoor space like a catio give an indoor cat something to do.
- Rechecks. Keep the follow-ups your vet sets, especially after a blockage or stones, since both can come back.
A cat who suddenly drinks much more than usual and makes big puddles has a different problem, often kidney disease, diabetes or an overactive thyroid. See why your cat might be drinking a lot of water.
When to Call Your Vet
How urgent | What you notice |
|---|---|
Go now, day or night | Squatting with drops or nothing coming out (male or female); crying in the box; a male licking his penis area while straining; urinary signs plus vomiting, not eating, weakness or hiding; you can't tell if your cat is trying to pee or poop |
Book a visit for today or tomorrow | Pink or bloody urine; many small pees, or peeing outside the box while still passing normal amounts; a first episode; a repeat episode in a senior cat |
Bring it up at the next routine visit | Your cat had FIC before, is fine now, and you want help with the home plan, weight or diet |
Stuck between two rows? Pick the more urgent one. Vets would much rather see a cat who turns out fine.
Outlook and Recurrence
Once the cause is known, the outlook is mostly good. FIC flares usually settle within 2 to 7 days, treated or not (iCatCare), and a 2022 review in Frontiers in Veterinary Science found that 80-90% of non-obstructive cases never come back. The vet visit still matters: the cat is hurting, and a stone or blockage has to be ruled out.
Most blocked males pull through with prompt care. Studies cited by iCatCare put survival to discharge at 91-94%, but 11-58% block again at some point, and Cornell adds that cats who have had stones are more likely to form new ones. Keeping the rechecks and sticking with the plan is how you tilt those odds.
FAQ
Is FLUTD an emergency? That depends on whether urine is getting out. Straining with little or none, especially in a male, is an emergency. A cat still passing normal amounts needs a vet visit soon, not tonight.
Is FLUTD the same as a UTI? No. FLUTD is the set of signs. A urinary tract infection is one possible cause, and an uncommon one in healthy adult cats.
Do female cats get FLUTD? Yes. Females get FIC and stones too, and infections are more common in females than males. A full blockage is the rare part, since a female's urethra is wider.
Can FLUTD come back? It can. FIC often recurs, stones can re-form and blocked cats can block again, which is why your vet plans for the long term instead of only treating the flare.
Sources
- iCatCare (formerly ISFM): 2025 consensus guidelines on the diagnosis and management of lower urinary tract diseases in cats (Taylor et al., J Feline Med Surg, 2025)
- Cornell Feline Health Center: Feline Lower Urinary Tract Disease
- Merck Veterinary Manual: Lower Urinary Tract Disease in Cats
- International Cat Care: Urethral obstruction in cats
- He C et al.: Prevalence, risk factors, pathophysiology, potential biomarkers and management of feline idiopathic cystitis: an update review (Front Vet Sci, 2022)
- VCA Animal Hospitals: Cystitis and Lower Urinary Tract Disease in Cats
This article is for general information and is not a substitute for advice from your veterinarian.
