Feline Idiopathic Cystitis (FIC) in Cats

Brittany Grenus, DVM
By Brittany Grenus, DVM on Mar. 24, 2022
Shot of a fluffy black and white kitten curiously checking out the kitty litter box stock photo

In This Article


What Is Feline Idiopathic Cystitis (FIC) in Cats?

Feline idiopathic cystitis, also known as feline interstitial cystitis or FIC for short, is a type of feline lower urinary tract disease that causes inflammation of the bladder in cats.  

 “Idiopathic” means that the cause of the disease process is unknown; “interstitial” refers to the location of the inflammation in the interstitium, which is the space between the cells in the bladder. This inflammation leads to a thickening of the bladder wall, which can be seen on an ultrasound or during cystoscopy (a procedure in which a scope is used to view the bladder).  

FIC causes symptoms that mimic a urinary tract infection (UTI). The key difference: a UTI is caused by bacteria, while FIC is considered a sterile disease (no bacteria are present).  
That doesn’t mean FIC is harmless, however. If the inflammation becomes severe enough, it can cause an obstruction (blockage) of the urinary tract and prevent your cat from being able to urinate, which is a medical emergency. If you notice your cat is straining to urinate, contact your nearest animal hospital immediately.  

Symptoms of Feline Idiopathic Cystitis (FIC)

Common symptoms of FIC may include:  

  • Straining to urinate 

  • Urinating more often (more frequent trips to the litter box) 

  • Urinating smaller amounts more frequently 

  • Blood in the urine 

  • Urinating outside the litter box, especially on cool, smooth surfaces such as tile or hardwood floors 

  • Licking excessively at the genital region 

  • Crying out or meowing while urinating 

  • Lack of energy 

  • Decreased appetite 

  • Vomiting or diarrhea 

  • Decreased social interaction (hiding) 

If your cat’s urethra (the tube through which urine leaves the body) has become obstructed (blocked), they will produce little to no urine and cry out often. They also will likely exhibit many of the other signs listed above. This is a medical emergency. Please seek veterinary care immediately.  

Causes of Feline Idiopathic Cystitis (FIC)

No one knows what causes FIC. Idiopathic means that the cause of a disease process is unknown. 

FIC occurs most often in young- to middle-aged cats that are less than 10 years old. Cats that are overweight are also at higher risk. Male cats are most prone to this problem, but females can also develop it. Experts believe that stress plays a role, as cats who experience sudden changes to their routine or environment and cats that live in multi-cat households are more likely to develop FIC.   

How Veterinarians Diagnose Feline Idiopathic Cystitis (FIC)

FIC is a diagnosis of exclusion, meaning that your vet will diagnose it only after ruling out all other potential conditions that might cause similar symptoms. This process can be expensive and stressful, but it is necessary.  

Conditions to rule out before diagnosing FIC include: 

  • Bladder stones 
  • Urinary tract infection (UTI) 

  • Urethral obstruction (blockage of the urethra); this can also occur secondary to FIC 

  • Cancer  

  • Acute kidney injury 

  • Idiopathic renal hematuria, a rare condition that causes kidney bleeding 

  • Blood clotting disorders 

  • Toxin ingestion 

  • Prostate disease (rare in cats) 

In order to check for these other conditions, your vet might recommend one or more of the following tests:  


Your vet will use a small needle to penetrate your cat’s bladder and collect a sterile sample of urine that is analyzed in a lab. (A “free catch” sample—which entails collecting urine after your cat has voided naturally—can be used, but it won’t be sterile and might lead to a false positive for a UTI.) If your cat has a UTI, lab analysis will detect bacteria in the urine. In a cat with FIC, the results will likely be abnormal (crystals, blood, protein, white blood cells, or skin cells may be present in the urine), but bacteria won’t be present.   

Urine Culture 

This takes urinalysis a step further by placing the sample in a petri dish and keeping it in a warm, dark incubator to allow any bacteria that might be present to grow. It’s the most accurate way to ensure your cat does not have a UTI. If your cat does have a UTI, the bacteria grown will be tested against different antibiotics to determine which ones would be most effective to treat the UTI.  

Urine Protein: Creatinine Ratio (UPC) 

This test compares the level of protein in the urine to the level of creatinine, a substance excreted by the kidneys. In healthy cats, the amount of protein is significantly less than the amount of creatinine. UPC is often elevated in cats with FIC.   

Abdominal X-rays 

A basic imaging test is often used to look for both bladder and/or kidney stones. Sometimes contrast dye is used so that the vet can see whether the urethra is blocked or thickened.  

Abdominal Ultrasound  

This test uses soundwaves instead of radiation to look for abnormalities in the bladder and kidneys, including stones.   

Urethrocystoscopy (Scoping the Bladder)  

Your vet will put a scope (thin tube with an attached camera) into the urethra and bladder to view the bladder wall and check for cancer.   

Exploratory Cystotomy With Histopathology 

This is a type of surgery in which the bladder is cut open so your vet can look for signs of cancer and take samples of the bladder wall to send to a lab for analysis.   

Urethrocystoscopy and exploratory cystotomy are typically reserved for cats that experience persistent or frequent, recurrent episodes of FIC and are used primarily to rule out bladder cancer, which is rare in cats.  

Treatment of Feline Idiopathic Cystitis (FIC)

Because the cause of FIC is unknown, there’s no medication that directly treats it. The most important aspect of managing FIC is to ease your cat’s discomfort. Your vet might prescribe pain relievers such as butorphanol or buprenorphine, which are low-dose opioids. Gabapentin is a drug in a different class that may also be used to control pain.  

If your cat’s urethra is blocked, it will require much more extensive treatment. After the initial emergent treatment, some of the medications your vet might prescribe include, but are not limited to acepromazine, prazosin or phenoxybenzamine, which are medications designed to help the urethra relax. Unfortunately, one of the main causes of the blockage is inflammation, and these medications don’t address the underlying inflammation.  

Given that inflammation is a big part of FIC, you might assume that your vet would advise taking a non-steroidal anti-inflammatory drug (NSAID) like meloxicam. Unfortunately, no studies have demonstrated that NSAIDs help with FIC.  

Some vets also recommend injections of a polysulfated glycosaminoglycan (PSGAG) such as Adequan. This is a drug that is typically used for joint issues to help prevent the breakdown of cartilage in the joint. However, the bladder also happens to be lined by this substance. In cats with FIC, recent studies have shown that they have a breakdown of the PSGAG layer on the bladder wall, and the injections may help to replace it. While it hasn’t been directly proven, it is suspected that PSGAG injections may help cats to recover faster from an FIC episode.   

Recovery and Management of Feline Idiopathic Cystitis (FIC)

There are several things that can be done to help your cat recover from FIC and prevent future episodes.   

Prescription Diets 

One change is a switch to a prescription diet that is high in antioxidants and omega-3 fatty acids, which combat inflammation. Your vet might recommend Hill’s c/d, Hill’s c/d Multicare Urinary Stress, Royal Canin Urinary SO, or Royal Canin Multicare Urinary and Calm.

Increased Water Consumption  

It has not been proven but drinking more water might help prevent FIC from returning. Feeding your cat an exclusively wet-food diet and using a water fountain may help to increase water consumption. Cats tend to like running water better than still water. 

Environmental Enrichment  

Environmental enrichment helps to decrease stress in cats, which is suspected to be a major factor involved in causing FIC. Increase more activity time with your cat, and consider providing extra climbing structures, viewing, and resting perches, and scratching posts. Also make sure that you’re frequently changing the litterbox and that you have an appropriate number of litterboxes in your home. It may surprise you, but the recommended number of litterboxes is one more than the number of cats you have.  


A synthetic version of a calming cat pheromone Feliway may help to decrease stress and, in turn, reduce the chances of future FIC episodes.  

Other Therapies 

L-Tryptophan and Alpha-Casozepine are supplements that may help to decrease stress in cats, but more research on them is needed. Acupuncture might also help cats who routinely experience FIC.  

Feline Idiopathic Cystitis (FIC) in Cats FAQs

How long does idiopathic cystitis last in cats?

Symptoms can usually go away on their own in five to seven days unless the urethra becomes blocked.

Do cats outgrow idiopathic cystitis?

No. It’s unclear why some cats have recurrent episodes, but others do not. Research has shown that 46% of cats who have an episode will never have another one, but an unlucky 12% have more than six recurrences.

Can feline idiopathic cystitis be cured?

Cats can recover from an episode of FIC. However, approximately 50% of them will have a recurrent episode within one year, so they should be monitored closely.

How long do cats with feline idiopathic cystitis live?

They can have a normal lifespan, as long as FIC is managed and treated appropriately.  


  1. Chew, Dennis J. “Idiopathic (Interstitial) Cystitis: New Concepts in Pathophysiology, Diagnosis and Treatment (Parts I & II).” Veterinary Information Network, Department of Veterinary Clinical Sciences, The Ohio State University College of Veterinary Medicine, Apr. 2012, www.vin.com/apputil/content/defaultadv1.aspx?id=5328238&pid=11349&

  1. Specht, A. “Try Not to Let Cats Think Outside the Box – What we Know About Managinf FIC. Veterinary Information Network, Atlantic Coast Veterinary Conference, 2017. 

  1. Lane, IF. “Strategies for Refractory Feline Lower Urinary Tract Disease.” Veterinary Information Network, Western Veterinary Conference, 2012. 

  1. Eggertsdottir AV, Blankvandsbraten S, Gretarsson P, et al: Retrospective interview-based long-term follow-up study of cats diagnosed with idiopathic cystitis in 2003-2009. J Feline Med Surg. 2021 Vol 23 (10) pp. 945-51. 

Featured Image: iStock.com/Adene Sanchez


Brittany Grenus, DVM


Brittany Grenus, DVM


Dr. Brittany Grenus graduated from Tufts Cummings School of Veterinary Medicine in 2018 with her doctorate in veterinary medicine and a...

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