WHAT IS INTERSTITIAL CYSTITIS?

Many cat owners are familiar with the signs of feline lower urinary disease in the cat. Whether we call the syndrome FUS for feline urologic syndrome or use the new name of FLUTD for feline lower urinary tract disease, it amounts to bladder pain, straining, and bloody urine.  Interstitial cystitis (“cystitis” simply means inflammed bladder) is human disease that is also characterized by excruciating bladder pain and straining. In 1990, Dr. M. Clasper made the suggestion that these two conditions might be closely related such that humans could benefit from studies involving affected cats and affected cats could benefit from studies of affected humans.

YOU KNOW A PERSON HAS INTERSTITIAL CYSTITIS WHEN:

There are several diagnostic and historical features that “clinch” this diagnosis in a human:

• The person must experience urinary pain and/or urgency. The problem usually has been going on for more than 9 months and the person must have a urination frequency of at least eight times a day.
   
• The person must have less than 350cc (about a 1 and ½ cups) of bladder capacity while awake.
   
• No involuntary bladder contractions when the bladder is filled at a certain rate during a special measuring procedure called cystometry.
   
• Waking at night to urinate is usually a problem.
   
• Victims of this disease are usually over 18 years of age.
   
• Next, under anesthesia a tiny camera is inserted up the urethra to examine the surface of the urinary bladder.  The bladder is distended with water to an extent that is far greater than would naturally occur simply by holding one’s urine even for a long time. The bladder surface is checked for special branching bruises called glomerulations.  Glomerulations must be present on ¾ of the bladder surface and each ¼ of bladder surface must have at least 10 glomerulations.
   
• If glomerulations are not seen or are not seen in the numbers described, interstitial cystitis is still diagnosed if something called a Hunner’s ulcer is found.

Some of the above criteria cannot be applied to cats directly as cats do not have the same waking/sleeping patterns as humans, will not tolerate cystometery while awake, do not have comparable bladder capacity or life span to humans etc. Clearly, though, a lot of this fits with the feline syndrome.

THERE’S MORE:

Further studies comparing biopsy samples of affected humans to affected cats showed some interesting similarities:

• Humans with interstitial cystitis show an increase in sensory nerve numbers in their bladders. Cats with FLUTD show the same thing.
   
• Humans with interstitial cystitis show loss of the mucous bladder lining that should be protecting their bladder tissues from the irritants in urine.  Similar findings hold true for cats.
   
• Both humans and cats also have a waxing/waning disease course. In other words, in both species the condition comes and goes recurrently.
   
• In both species there seems to be a stress factor in times of recurrence.

SO, DO SOME OF THESE CATS HAVE INTERSTITIAL CYSTITIS?

The important thing to realize is that “interstitial cystitis” is not really a specific diagnosis in humans. The term seems to reflect a collection of clinical signs and lab findings just as the term FLUTD does for cats. The biopsy findings that looked so specific are also reflected in other disease conditions. It is possible that we are seeing a general bladder response to inflammation and still are no closer to a real cause; we have simply described the syndrome in more detail. For a while cats were receiving the diagnosis of “interstitial cystitis” as a diagnosis in the same way other cats with the syndrome were diagnosed with bladder stones, bladder infections, or bladder tumors. It appears that the term “interstitial cystitis” is being replaced, at least in cats, with the term “idiopathic cystitis,” another name for bladder inflammation of unknown cause.

TREATMENT?

Failure to understand the cause of interstitial cystitis in people has not meant that treatment is unavailable; many treatments are available to help the many people who suffer from this condition. In the June 1999, issue of Compendium on Continuing Education for the Practicing Veterinarian, Dr. Tina Kalkstein et. al. review how some of these treatments have panned out for cats:

DMSO - This is an anti-inflammatory solvent used to treat an assortment of inflammatory bladder conditions in humans. It is directly infused into the bladder by catheter. It is reported to improve 50-90% of human patients.  DMSO has certainly been used and continues to be used in cats though studies have not been able to show any clear benefits.

PENTOSAN POLYSULFATE SODIUM (brand name Elmiron) - This is a substance called a glycosaminoglycans (the substance that makes up the mucous bladder lining). Remember that this substance is deficient in affected cats and humans. This medication is given orally and 28-40% of humans with interstitial cystitis experience remission of clinical signs.  This medication is becoming popular in affected cats but controlled studies are still lacking.

AMITRYPTILINE (brand name Elavil) - This is an anti-anxiety medication that also has anti-inflammatory properties.  In humans, 64% of patients experienced remission of signs. Statistics are not available for cats.

ANTI-HISTAMINES - Hydroxyzine (brand name atarax) has been used in humans with interstitial cystitis in an attempt to relieve bladder inflammation. (Histamine is an important inflammatory mediator in the human).   Approximately 50% of human patients showed improvement. No information is available regarding cats with FLUTD though hydroxyzine is readily used in the treatment of allergic skin disease in cats.

Our understanding of Feline Lower Urinary Tract Disease
continues to be limited as there appear to be many causes.

A definitive treatment is not likely to be found
until there is a means to classify individuals
based on the cause of their syndrome.
Until then, we have theory only.