Feline Lower Urinary Tract Disease

What is feline lower urinary tract disease?

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 will experience FLUTD, it is more serious in males than females as they have a narrower urethra, making them more prone to becoming blocked. Urethral obstruction is a medical emergency.



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

He may also investigate further by performing a urinalysis, blood work, ultrasound or x-ray.


Feline Idiopathic Cystitis (FIC) or unknown cause:

The most common cause of FLUTD in cats and makes up 50 – 65% of cases. Cystitis means bladder inflammation. Even with extensive testing, much of the time a cause of the symptoms cannot be determined.

Urinary stones (uroliths):

Struvite or calcium oxalate are the most common forms of urinary stones. Uroliths account for 15 – 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. This appears to have worked well for struvite crystals, but not for calcium oxalate crystals. Diet plays an important role in the formation of urinary stones and crystals.

Urethral obstruction:

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


FLUTD has been linked to stress in some cases. So reducing stress in the household may be of help. This includes providing enough litter trays in hour household. A general rule of thumb is one litter tray per cat, plus one extra. So, if you have two cats, three trays. Obviously, this isn’t always practical, and if you have fewer litter trays try scattering them around the house, and ensure they are cleaned frequently.


With an incidence of less than 1%.

Trauma or anatomical defects of the urethra:

This occurs in less than 1% of cases.

Bacterial infection:

An uncommon cause of FLUTD with an incidence of 1 – 3% of cases.

Home treatment

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

  • As 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 the concentration of the urine. It is also beneficial to aim for a pH below 6.5. pH in 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.
  • Diet: Moisten dry food or change to canned/raw food. Dry food contains approximately 10% water, whereas canned or raw food contains approximately 70% water. Avoid fish flavoured food. Feed a diet that increases the acidity of urine or increases thirst.
  • Increase water consumption: Encourage drinking by other means, such as providing a drinking fountain for your cat.
  • Urine pH: Try to feed a diet that keeps the urine pH below 6.5. Unfortunately, long-term use of an acidifying does carry some risks, one of which is the increased chances of developing calcium oxalate urolithiasis.*2
  • Antibiotics: This form of treatment is used for mild cases of FLUTD and the decision to prescribe antibiotics will depend on the severity of the case. Most cases of FLUTD resolve themselves within 5 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.
  • Medications: Amitriptyline is an antidepressant and analgesia (painkillers) are two medications that can help a cat with FLUTD.



If the cat is completely blocked then the veterinarian will 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 to empty the bladder. Alternatively, he may choose to catheterise the cat immediately. See below for info on catheterisation.


A urinary catheter is placed in the cat’s urethra to flush out any crystals or debris. Catheterisation on a cat takes place while the cat is under anaesthesia.

Fluid Therapy:

Intravenous fluids are administered to flush out the cat’s urinary system (particularly the bladder).


A procedure is performed on male cats who experience repeated bouts of FLUTD. It is also performed on cats whose systems were not fully flushed during the catheterization process. This surgery is known as a perineal urethrostomy and involves a partial amputation of the penis to the point where the urethral opening is larger. This will help reduce the risks of blocking, although it is still possible a small number of cats will become blocked even after the perineal urethrostomy.

Julia Wilson 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. She enjoys photography, gardening and running in her spare time. Full author bio Contact Julia