FIC/FLUTD/FUS(Urinary Tract Irritation in Cats)

FIC/FLUTD/FUS(Urinary Tract Irritation in Cats)

Animals Affected



FIC, FLUTD, and FUS are synonyms for a painful syndrome in cats. FIC is currently the most commonly used name. Its symptoms, listed below, mimic those of bladder infections. FIC is characterized by inflammation of the bladder and urinary tract which can be chronic or recurrent. The urine of these cats often is very strong, and may have an abnormal pH. As well, the syndrome has been correlated with crystals in the urine.

In male cats, FIC has the potential to lead to a life-threatening emergency situation known as urinary obstruction.

FIC stands for feline idiopathic or interstitial cystitis.  FUS stands for feline urologic syndrome. FLUTD stands for feline lower urinary tract disease. The three acronyms are used to describe one syndrome.


Cats with FIC may show one or more of the following symptoms.

  • Urinating outside of the litter box
  • Straining to urinate
  • Urinating with increased frequency and decreased output
  • Bloody urine
  • Vocalizing or howling in pain while urinating
  • Licking or excessively grooming genitals
  • Personality changes such as aggression or hiding
  • Attempting to urinate without producing urine

Risk Factors

  • Young cats suffer FIC at higher rates than elderly animals.  Cats aged three to seven years are at highest risk.
  • Hereditary factors (genetics) play a role in the syndrome.  Persians and Himalayans are disproportionately affected.
  • Poor quality diets may contribute to the syndrome. However, diet is not the cause of the syndrome; see below.
  • Some evidence suggests that overweight cats and cats that are kept strictly indoors suffer higher rates of FIC.
  • Nervous cats, aggressive cats, and individuals living in multiple-cat households are more likely to suffer from FIC.

It should be emphasized that the primary cause of FIC is related to the cat’s internal body chemistry. The interaction of a cat’s diet with its body contributes to the development of the syndrome. A change in diet can contribute to the resolution of the syndrome. However, a cat’s diet does not on its own cause or cure FIC.


  • Pain: FIC is an extremely uncomfortable syndrome.
  • House soiling can lead to damage to property and reduced bond between the cat and people in the house.
  • Some experts belive FIC can trigger bladder infections.  However, this matter is debated.
  • FIC is correlated with urinary obstruction in male cats. Urinary obstruction is a life-threatening emergency.
  • Bladder stones may develop in cats with FIC.
  • Without treatment, relapses are extremely common. Even with treatment, symptoms of FIC may periodically recur.


Diagnosis is based on symptoms, physical examination, and urine testing (urinalysis). Urinalysis may show abnormal urine pH or crystals in the urine. X-rays or ultrasound may be used to assess the structure of the bladder and to check for bladder stones.


Dietary modification is the mainstay of treatment. Several brands of food have been developed specifically to aid in the treatment of FIC and are available through veterinarians.

A dietary supplement called D,L-methionine may be used to alter urinary pH.  A dietary supplement called Cosequin® (containing glucosamine) is advocated by some practitioners to reduce pain and  inflammation in the bladders of cats with FIC.

Cats diagnosed with FIC should have access to multiple sources of fresh water to encourage water consumption. Litter boxes should be kept clean to encourage regular voiding of the bladder.

Severe or refractory cases may respond to treatment with anti-inflammatory medications or injections of fluids under the skin.

Amitriptyline is a medicine used for some bladder problems in people. Evidence suggests that it may help some cats suffering from FIC.

In male cats, medications including prazosin, phenoxybenzamine, or diazepam may be used to relax the urethra and reduce the likelihood of urinary obstruction.

Male cats suffering from urinary obstruction require emergency hospitalization and treatment.


Resolution of symptoms is the key indicator of success in treatment.

After a cat has been diagnosed with and treated for FIC, it is critical to perform follow-up urinalyses on a regular basis to ensure that the underlying issues with body chemistry are being properly addressed. This is true even the cat is showing no symptoms of the syndrome.


Some cats outgrow FIC over time. However, never assume that your cat has outgrown the syndrome without first discussing the matter with your veterinarian. Stopping treatment for FIC without appropriate veterinary supervision leads to a high rate of relapse.

Any time a male cat exhibits difficulty urinating, he should receive immediate veterinary attention to rule out the possibility of urinary obstruction.

The type of crystal most commonly found in the urine of cats with FIC is called struvite (synonyms: triple phosphate, magnesium ammonium phosphate). Another type of crystal that may be encountered is called oxalate.

Studies indicate that approximately 1.5% of cats suffer from FIC.

Copyright © Eric Barchas, DVM All rights reserved.
The contents of this page are provided for general informational purposes only. Under no circumstances should this page be substituted for professional consultation with a veterinarian.