Feline Lower Urinary Tract Disease (FLUTD)

At a glance

  • About: Feline lower urinary tract disease (FLUTD) is a group of conditions affecting the cat’s bladder and urethra.
  • Causes: Dry cat food diets can promote the formation of crystals and stones, stress, bacterial infection and tumours. Up to 65% of cats with FLUTD have no known cause.
  • Symptoms: Straining to urinate, frequent genital licking, crying in the litter tray, going to the toilet in other places, frequent trips to the litter tray, inability to urinate.
  • Diagnosis: Thorough physical examination along with baseline tests which include complete blood count, biochemical profile, urinalysis, ultrasound and, x-rays.
  • Treatment: A completely blocked cat will need to have his bladder emptied, fluid therapy, stone dissolving diets,
    antibiotics, and encourage water consumption to dilute the urine.

What is FLUTD?

Formerly known as FUS (Feline Urologic Syndrome), FLUTD (feline lower urinary tract disease) is a group of conditions affecting the cat’s lower urinary system and bladder, including urolithiasis (stones in the urinary tract), cystitis (inflammation of the bladder), urinary tract infection and urethral obstruction.

Approximately 1% of the cat population in the United States will experience FLUTD. The condition is more serious in males than females as they have a narrower urethra, this makes them more prone to blockages. Urethral obstruction is a medical emergency.

All cases of FLUTD have the same symptoms, but there are numerous causes, some of which are not fully understood yet.

Risk factors include neutering, obesity, dry diets, not drinking enough, stress and sedentary lifestyles.


Feline Idiopathic Cystitis (FIC) or unknown cause:

Cystitis is an inflammation of the bladder, and in cases with FIC, the cause is unknown. FIC is the most common cause of FLUTD in cats under the age of ten.

Urinary stones (uroliths):

Struvite crystals
Struvite crystals

Struvite or calcium oxalate are the most common form of urinary stones, and uroliths that occur are seen in 10 – 20% of cases. Your veterinarian will be able to perform an ultrasound or x-ray to detect urinary stones in your cat. Depending on the type of stone, it is possible to prescribe a stone-dissolving diet for cats with struvite crystals. Diet is believed to play an important role in the development of urinary stones and crystals.

Urethral obstruction:

Urethral plugs are usually composed of large quantities of matrix (protein) mixed with minerals. Some urethral plugs are predominantly composed of matrix, some may contain tissue fragments, blood cells, and cellular debris, and a few may be composed primarily of crystalline minerals.

An obstruction is a medical emergency and requires urgent veterinary treatment. A complete blockage can cause death within 3-6 days if left untreated.


Reducing stress in the household can help some cats. Inappropriate litter tray maintenance, inter-cat issues, changes in the home (new baby or housemate, increased hours at work).

Other causes:

Cancer, hyperthyroidism, diabetes, trauma or congenital defects, bacterial infection (5-10% of cases).



Your veterinarian will be able to give a tentative diagnosis based on a physical examination. Signs such as straining to go to the toilet, licking genitals. The bladder may feel large, full and distended, or small and thickened.

Baseline tests: Biochemical profile, complete blood count, and urinalysis (best collected by cystocentesis) to check the pH and concentration of the urine as well as look for crystals, blood or bacteria.

Urine culture: If the cat has a history of catheterisation or evidence of a urinary tract infection (pus in the urine).

Ultrasound or x-ray: These imaging techniques help the veterinarian evaluate the bladder and look for signs of cancer or stones.


It will be necessary to stabilise the cat and correct biochemical and electrolyte disturbances before anesthesia.

Unobstruct the cat:

If the cat is completely blocked, then the veterinarian may extract urine by placing a syringe through the abdomen and directly into the bladder and draw out the urine (cystocentesis). This is a fast and effective way of emptying the bladder in an emergency. Alternatively, he may choose to catheterise the cat immediately. See below for info on catheterisation.


The cat is placed under heavy sedation, and a thin plastic tube (catheter) is inserted into the penis and up to the bladder. A sterile solution is flushed through the catheter to push the obstruction back into the bladder where it can be dissolved or surgically removed. The bladder is flushed thoroughly to remove any remaining sediment. The catheter will remain in place for several days until the urine is clear, and the swelling has subsided.

Fluid therapy:

To correct electrolyte imbalances and replace lost fluids due to post-obstructive diuresis (increased production of urine once the cat has been unblocked, which results in the loss of water and salts).


Male cats who experience repeated bouts of FLUTD can benefit from a perineal urethrostomy. This surgery involves a partial amputation of the penis to the point where the urethral opening is larger to reduce the risks of blocking. It is still possible a small number of cats will become blocked even after the perineal urethrostomy.

Supportive care:

  • Urine output will be monitored to ensure IV fluid administration is correct.
  • Monitor kidney function.
  • Nutritional support.
  • Analgesics where necessary.

Drug therapies:

  • Medications to support normal urination by relaxing the smooth muscles (phenoxybenzamine or prazosin) and a skeletal muscle relaxant (diazepam or dantrolene) as well as relieving urethral spasms (spasmolytics).
  • Tricyclic antidepressants (TCAs) and Selective Serotonin Reuptake Inhibitors (SSRIs) to manage stress.
  • The decision to prescribe antibiotics depends on the severity of the case. Most cases of FLUTD resolve themselves within five days. However, since FLUTD has been known to cause severe pain and damage in many cats, it is better to be safe than sorry. Antibiotics can help in some cases.

When can the cat home?

Once the catheter is removed, the cat will be released once he can urinate on his own.

Home care

Treatment depends on the cause and severity of the condition and will also vary according to the type of crystals your cat has, should he/she have crystals.

Dietary changes: Cats can benefit from diets with a moisture level that is over 60%. Feed moist food such as canned or raw (or both).

Increase water consumption: Stone build-up is caused by urine which is too concentrated. It is important to try and get more fluids into your cat, to reduce this concentration. It is beneficial to aim for a pH below 6.5. pH. A cat’s urine usually ranges from 5.5 to 8.0, but diets that result in < 6.5 decreases the chances of struvite crystals forming. Empty and wash bowls at least once a day as water bowls develop a bacterial biofilm, with several pathogenic strains of bacteria and cause the water to smell.

Therapeutic diets: With the use of prescription diets such as Hills c/d or s/d, which support urinary health, maintains urine pH, dissolves stones, manage stress, and reduces inflammation.

Amino acids: L-tryptophan is a precursor for serotonin that inhibits neurotransmitters in the brain to stabilise mood.

Omega-3 and 6 fatty acids: These nutraceuticals can help by reducing inflammation, which plays a role in FLUTD.

Encourage litter tray use: To encourage frequent urination, provide enough litter trays for your household. One tray per cat, plus one extra. Remove solids twice a day and replace them with fresh litter once a week. Place in easy to access locations.

Reduce stress: Stress can cause the cat to hold onto its urine for longer than necessary, which can enhance the formation of crystals or stones. Address inter-cat issues with the help of your veterinarian or a certified animal behaviourist. Ensure there are multiple zones and resources for each cat. That includes litter trays, food bowls, beds, and where perches. Maintain a stable routine in which cats need to feel safe.


  • Julia Wilson, 'Cat World' Founder

    Julia Wilson is the founder of Cat-World, and has researched and written over 1,000 articles about cats. She is a cat expert with over 20 years of experience writing about a wide range of cat topics, with a special interest in cat health, welfare and preventative care. Julia lives in Sydney with her family, four cats and two dogs. Full author bio

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