Affects: Cats
Feline idiopathic cystitis (FIC) or feline interstitial cystitis or cystitis in cats, is one of the most frequently observed forms of feline lower urinary tract disease (FLUTD). Feline cystitis means "inflammation of the bladder in cats". The term idiopathic means unknown cause; however, certain behaviours have been known to aggravate the illness once it has been initiated. It can affect both males and females of any breed of cat. It is more commonly found in female cats; however, when males do exhibit cystitis, it is usually more dangerous.
Despite the shared terminology, cases of feline idiopathic cystitis, as opposed to human cystitis episodes, are sterile. In other words, they do not involve a primary bacterial infection. If upon investigation the inflammation of the feline bladder is in fact found to be the result of an infection, then it is described as a feline urinary tract infection (UTI) or less commonly, feline bacterial cystitis. In cats under the age of 10 years old, FIC is the most common urinary disease seen in cats and UTIs are very rarely encountered. However, in cats over 10 years of age, UTIs are much more common and idiopathic cases are much less frequently observed. On the other hand, FIC does show several similarities to an analogous disease in humans called bladder pain syndrome.
Signs And Symptoms: Feline idiopathic cystitis begins as an acute non-obstructive episode and is self-limiting in about 85% of cases, resolving itself in a week. In approximately 15% of cases, it can escalate into an obstructive episode ("blocked cat") which can be life-threatening for a male cat. The symptoms for both a non-obstructive and an obstructive episode are usually very similar and a careful § differential diagnosis is necessary to distinguish between the two.
Pathophysiology: Feline idiopathic cystitis is above all an inflammatory process.
Causes: Obstructive episodes occur in the rarer instances (approximately 15% of FIC cases) when the initial, § non-obstructive attack (see above) is not self-limiting and escalates into partial or full block of the urethra. In this case voiding of urine is impeded or altogether impossible. Obstruction occurs almost exclusively in male cats due to their long, narrow urethra. There are two reasons why a cat may obstruct ("block"):
Treatment Of An Acute Episode: Veterinary attention is essential if urine does not pass at all as the bladder could rupture and there is risk of death within 72 hours. The vet will usually attempt to relieve the blockage with a catheter, draining the backed-up urine and flush the bladder of any sediment (this may include crystals). This is an invasive, delicate procedure which will require either heavy sedation or general anaesthetic. The cat should then be hospitalised with the catheter in place and hydration administered intravenously to encourage healthy urination and good kidney function, ideally for three days. While the catheter is in place, intravesical instillation (which is also used to treat human interstitial cystitis) may also be administered to repair the compromised bladder lining. When the catheter is removed, the cat must be able to show he can urinate with good function before he can be discharged. With this proviso, he can return home and the anti-inflammatory and anti-spasm medication indicated for non-obstructive cases will be prescribed, as well as oral supplements to calm the cat and replenish the protective bladder lining (see above). Medication should be given for long enough to ensure symptoms properly subside at which point it should be slowly tapered off. This can usually take around 10 – 14 days but could take longer. Stopping medication too early can result in re-blocking.
Even after the cat is unblocked, the underlying inflammatory syndrome will continue for some days at home (particularly since the catheter itself will have irritated the urethra). Therefore, some of the clinical signs for non-obstructive FIC may still be apparent post-discharge until the inflammation subsides and cat has fully recovered (e.g. frequent voiding, blood in urine, possible leaking). However medication should alleviate the severity and discomfort as well as assisting recovery. The owner must focus above all on good hydration (from a wet food diet if the cat will accept it) and frequent urination to keep the bladder clear. Wet prescription diets may be recommended but if the cat refuses this (cats often avoid eating unfamiliar food when stressed), any high quality, high moisture, high animal protein wet food which the cat finds appealing may be administered. A urinary acidifier (e.g. DL-Methionine) may be added to the latter to prevent struvite crystal formation but as animal protein is already acidic, it is not strictly necessary. In any case, excessive acidification should be balanced against the risk that it could irritate the inflamed bladder wall. This could trigger recrudescence i.e. a further acute attack, as well as encouraging calcium oxalate crystal formation which forms in highly acidic urine. An acidifier should never be added to prescription urinary food as this has already been acidified. Acidification or prescription foods are always secondary to the first priority of good hydration from any wet food the cat finds palatable. Dry food of any sort (including prescription dry food) should be avoided.
Environmental modification to reduce stress, itself suspected to be one of the principal causes of FIC, must also be considered (see below) as the risk of re-blocking is highest within the first week after catheterisation.