Urinary Tract Infections in Cats

Feline Idiopathic Lower Urinary Tract Disease in Cats

Idiopathic Feline Lower Urinary Tract Disease (IFLUTD) is a general term for disorders characterized by blood in the urine; difficult or painful urination; abnormal, frequent passage of urine; and urinating in inappropriate locations.

A subset of FLUTD is idiopathic and is known variably as Feline Idiopathic Cystitis (FIC), Feline Urologic Syndrome (FUS), or Interstitial Cystitis. These conditions develop when the bladder and/or urethra (the lower urinary tract) become inflamed without any physical cause.

To diagnose FLUTD, your veterinarian will first want to check for a urinary tract infection and urinary stones or crystals. The vast majority of FLUTD (64 percent) is idiopathic—that is, no identifiable physical cause.

Only 2 percent of cats with urinary signs have infections, while up to 14 percent may have urinary crystals or stones. In elderly cats, these percentages change as cats become more likely to develop infection and symptoms related to chronic kidney disease.

FLUTD occurs in both male and female cats. The incidence of blood in the urine, difficult or painful urination, and/or blockage of the urethra in domestic cats in the U.S. and the U.K. has been reported at approximately 0.5 percent to 1 percent per year.

While it can occur at any age, it is found most commonly in cats between the ages of one and four years old. The idiopathic variety is uncommon in cats less than one year of age and in cats greater than 10 years of age.

Symptoms and Types

  • Difficult or painful urination (vocalizing while urinating)
  • Blood in the urine, outside the litter box
  • Abnormal, frequent passage of urine
  • Urinating in inappropriate locations
  • Blockage of urine flow through the urethra to outside the body
  • Thickened, firm, contracted bladder wall, felt by the veterinarian during physical examination


By definition, this is a disease that arises without a known physical cause. Often, FLUTD is caused by an event or change in the cat’s environment.

This may be something identifiable like construction going on inside or near the home, having houseguests over, or the addition of a new pet. Sometimes the cause of your cat’s stress is invisible to humans. Nevertheless, your cat feels ill and needs treatment.

When cats do have a physical cause for their painful bladder, your veterinarian will readily identify the cause and recommend a specific course of treatment. 


Your veterinarian will rule out a range of disorders in arriving at a diagnosis. Some possibilities are metabolic disorders, including various types of kidney stones and obstructions.

A urinalysis will be ordered to determine whether there is a physical cause such as infection or urinary crystals. A detailed physical examination will determine whether physical trauma, disorders of the nervous system, anatomical abnormalities, or something as simple as constipation, could be the factors behind the symptoms.

Your veterinarian may recommend bladder X-rays or an ultrasound. X-rays are useful in locating kidney or bladder stones if they are suspected, and an ultrasound is useful at visualizing the tissue of the urinary bladder and the bladder contents.


  Next >