Feline Lower Urinary Tract Disease (FLUTD) in cats


What is FLUTD?

FLUTD stands for feline lower urinary tract disease. This is a term used to describe a collection of conditions which can affect the bladder and/or urethra (tube from the bladder to the outside).

The most common conditions causing FLUTD are:

  1. Urolithiasis (stones in the bladder and/or urethra)- there are various different stones which can form in the urinary tract resulting in FLUTD due to irritation of the bladder/urethral lining.
  2. Structural defects- rarely some cats can be born with anatomical defects which can lead to signs of FLUTD. Alternatively a defect such as a stricture (narrowing of the urethra secondary to scar formation) can develop in older animals.
  3. Bacterial infection- this is a relatively uncommon cause of FLUTD. In some cases an infection can be present alongside another condition.
  4. Cancer- tumours of the bladder and/or urethra are thankfully rare in cats.
  5. Urethral plugs and urethral spasm- urethral plugs are accumulations of cells, cyrstals and other debris which, if formed in the urethra, can block urine output from the bladder in male cats. In addition spasm (muscular contraction and narrowing) of the urethra can occur which can also result in blockage of the urethra.
  6. Feline Idiopathic Cystitis (termed F.I.C.)- this is the most common cause of FLUTD (around 60-70% of cases). The exact cause of F.I.C. is unknown although there are studies which suggest that this condition results from an abnormal response to stress. This condition is diagnosed after excluding all other causes however many cats with other conditions (for example urethral plugs/spasm) will also have F.I.C.

What are the signs of FLUTD?

The most common clinical signs of FLUTD relate to abnormalities of urination. In some cats which only urinate outdoors signs may not be apparent at home. If observed signs would include:

  1. Straining to urinate
  2. Crying when urinating
  3. Urinating in inappropriate places
  4. Urinating more often than normal
  5. Smaller volumes of urine produced when urinating
  6. Inability to urinate (this can be life threatening, requiring immediate veterinary attention).
  7. Blood visible in the urine
  8. Over-grooming the perineum
  9. Signs of pain/inappropriate aggression particularly around the hind end.

How is FLUTD investigated?

Initially a thorough history including identification of any potential factors that could lead to stress (i.e. house move, new pet in the environment or building work at home) is taken. A physical examination will then be performed. In male cats the bladder size and texture will carefully be assessed to identify whether urethral blockage (obstruction) is present. Next a combination of some or all of the following tests may be performed:

  • Urinalysis: This may be collected at home (free-catch) or by taking a sample directly from the bladder using a needle. The urine concentration is assessed alongside checking for bacteria, blood, protein or crystals.
  • Blood tests: A blood sample may be taken, especially in cats with suspected urethral blockage. This is to assess kidney function and blood salt (electrolyte) concentration. In addition some cats can have alterations in blood calcium levels which could predispose to stone formation.
  • Abdominal ultrasound: This can be used to check for any signs of a tumour or stones in the bladder. The bladder wall thickness can also be assessed.
  • X-rays: Some bladder or urethral stones (uroliths) can be visible on an X-ray of the abdomen.

How is FLUTD treated?

The treatment of FLUTD will vary depending on the underlying cause. In general FLUTD is a painful condition and therefore in all cases pain relief is normally administered. A short summary of possible treatments for each cause is given below.


If bladder stones are causing clinical signs they may need to be removed. Some types of stones (e.g. struvite) can be dissolved by changing to a specifically manufactured prescription diet. Others are normally removed surgically. If a urethral stone is present and causing blockage then additional, emergency treatment is required. This is discussed in more detail in the “Urethral plugs and urethral spasm” section.

Structural defects

Often surgery is required to correct structural defects. In cats with urethral strictures, dependent on the location, a procedure called perineal urethrostomy can be performed to open the urethra above the narrowing, creating a permanent new location for urine to exit.

Bacterial infection

Bacterial infections are treated with antibiotics. Due to the increasing prevalence of resistance, antibiotics should only be used in cats where there is either a very strong suspicion of infection or confirmed infection (particularly as this is less common).


The most common type of cancer found in the bladder is called transitional cell carcinoma. This is generally treated with a combination of chemotherapy and non-steroidal anti-inflammatories. Other benign tumours may be treated by surgical removal.

Urethral plugs and urethral spasm

Urethral plugs or spasm resulting in blockage of the urethra (normally in male cats due to the diameter, shape and length of the urethra) can be life threatening. This is because if it is left untreated the kidneys can become damaged and blood salts can become deranged leading to heart problems and even death.

Cats with urethral blockage are rapidly assessed. Normally pain relief and muscle relaxants are administered alongside fluid therapy into the vein. The patient is then either anaesthetised or heavily sedated and removal of the blockage is performed (normally by flushing and placement of a catheter through the urethra into the bladder). After the catheter is passed into the bladder it is often secured in place for a few days. This is prevent immediate re-blockage and to allow time for the spasm and associated inflammation/swelling of the urethra to improve. The catheter is then removed and the patients are observed to ensure that they are able to urinate.

In cats with kidney problems due to the blockage fluid therapy into the vein will need to be continued until the kidneys improve. Sadly in some cases permanent damage to the kidneys can occur resulting in chronic kidney failure. Thankfully this is uncommon.

Rarely it is not possible to unblock the urethra with a catheter. In addition some cats have recurrent episodes of urethral blockage despite preventative therapy. In this specific but small group of patients a perineal urethrostomy can be performed (as discussed in structural defects). It is important to understand that there can be serious complications associated with the surgery and it does cure the condition.

Feline Idiopathic Cystitis (F.I.C.)

The management of F.I.C. is complex as the cause is multifactorial. Factors thought to contribute to the condition include a defective bladder lining, stress (specifically an individual’s inappropriate reaction to stress) and inflammation caused by the central nervous system. In humans a similar condition exists called ‘interstitial cystitis’. Changes in the bladder lining and brain of cats with F.I.C. are similar to those found in humans with this disease.

There are various different treatments available, with evidence behind each recommendation varying in quality and quantity. A short summary of each therapy area is given below:

  1. Dietary medication
    Simply changing from dry to wet (sachet or tinned) food can help to increase the amount of water consumed. This can result in the production of more dilute urine. There are various prescription urinary diets available which may be recommended in specific circumstances (particularly if struvite stones are present or high blood calcium).
  2. Increasing water intake
    In addition to changing to wet food, cats with F.I.C. should be encouraged to drink more water to enhance the production of dilute urine. This can be achieved by providing a water fountain, ensuring fresh water is always available in multiple locations or adding water to food.
  3. Litter tray number and location
    There should be at least one litter tray for each cat in the household. These should be placed in different locations, preferably in less busy areas of the home. The type of litter can also have an impact and therefore providing a few different types to evaluate which is preferred can help. Cats that normally urinate outside should not be forced to use a litter tray.
  4. Identification and modification of stressful stimuli
    This is a very important part of management but is often the most difficult to practically achieve. If an event that would be anticipated to cause stress is to occur (i.e. house move or new pet) then measures to minimise the impact should be considered. It is thought that conflict with another cat in the same household is the most common cause of stress in cats with F.I.C. Signs of this may not be immediately obvious and resolving or improving this can be difficult.Encouraging play and the addition of new toys to the environment can help. In cats that are indoors only, allowing some outdoor access can help (if safely possible). Consultation with a behaviourist can also be required to identify and improve causes of stress.
  5. Painkillers
    Chronic or intermittent pain relief can be prescribed. There are various types available including non-steroidal anti-inflammatories and opiods.
  6. GAG replacers
    GAG replacers theoretically help cats with F.I.C. by improving the abnormal bladder lining. There are multiple different formulations available and some are present in prescription diets targeted for urinary tract disease.
  7. Synthetic pheromone therapy
    Feliway® is a feline synthetic pheromone which may help to reduce stress and anxiety. There are various ways this can be used (either a spray or a plug-in diffuser). Further advice is available from the website and there are different products available to use in different scenarios (i.e. in multi-cat homes or during times of anticipated stress).
  8. Anti-depressants
    In extreme cases human anti-depressants can be used. These are normally reserved for severely affected cats that are refractory to all other forms of therapy.


If you have any questions about your cat’s condition, or his or her treatment, please do not hesitate to contact us.

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