Feline idiopathic cystitis (FIC) is a sterile, inflammatory process causing signs of lower urinary tract disease (LUTD). It
affects 1.5% of cats presented to primary care veterinarians.21 It is the most common diagnosis for young cats with LUTD (the second most common being urolithiasis). FIC is important not
only because of the pain and distress it causes patients, but also because it is highly associated with house soiling, the
leading cause of relinquishment of cats to shelters.
FIC appears to be a modern disease, having first been mentioned in the early 1990s when it was discovered that no specific
diagnosis could be made in over 50% of cats with LUTD.19 Diet and environment play important roles.
Terminology can be confusing with this disease. "Interstitial cystitis" is a term best reserved for that subset of FIC patients
with chronic or frequent signs and cystoscopic findings similar to humans with interstitial cystitis. FIC is a more generic,
umbrella term for those cats with acute or chronic signs of LUTD where cystoscopy has not been performed or has not revealed
changes associated with interstitial cystitis.
Approximately 60-70% of cats under 10 years of age with signs of LUTD have no specific cause, and are referred to as having
FIC. In one study of 109 cats with signs of LUTD, 64% were determined to have FIC.5 Urolithiasis affects about 10-20% of cats presenting with LUTD. Several studies have shown that less than 2% of cats with
LUTD signs have bacterial urinary tract infection (UTI). Recently, however, a study of 134 Norwegian cats with clinical signs
of lower urinary tract disease found 33% had bacteriuria.13 Cats with FIC are generally young to middle-aged when diagnosed; FIC is less likely as a new diagnosis in geriatric cats
and other causes of LUTD should be pursued aggressively in this age group.
Patient Signalment and Risk Factors
Most patients are 2-6 years of age at diagnosis; FIC is uncommon in cats under 1 year of age. Certain factors have been associated
with increased risk in several studies:
o Breed: lower in Siamese, higher in Persians
o Gender: neutered male and spayed female
• Age at neutering not important
o Increased body weight, decreased activity
o Multiple cat households
o Exclusive dry food diet 6
o Indoor lifestyle
In one questionnaire-based study of 31 cats with FIC compared to 24 normal housemates and 125 other normal cats8 , certain risk factors were identified: male gender, being overweight, pedigreed breed, and stress factors, especially conflict
with another cat in the home.