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.
Non-obstructive FIC The vast majority of FIC cases are non-obstructive. In the case of non-obstructive FIC, the underlying inflammatory process has begun but the disease has not progressed to the extent that it prevents urination (i.e. the cat has not "blocked"). Non-obstructive FIC usually resolves spontaneously within 5 to 7 days regardless of treatment. The cat's lower urinary tract is inflamed and the urethral passage may have narrowed due to swelling but it remains open ("patent") and it can urinate to varying degrees, albeit in discomfort. Clinical signs apparent during an acute episode may include:
Frequent trips to the litter box, possibly with straining due to inflammation triggering urethral spasms. Sensation of incomplete voiding. Production of small volumes of urine. Possible presence of blood in the urine due to glomerulation or Hunner's ulcers. Odorous urine. Irritability. Lack of interest in normal activities. Hiding in a dark, quiet location (hiding is part of the cat's stress coping mechanism and should not be interfered with unnecessarily). Experiencing pain during the act of urination, characterized by vocalisation. However, since cats are evolutionarily adept at hiding their pain, vocalising, crying, or any other audible cue may not always be observed. Reluctance or refusal to urinate due to the pain of excretion. This causes urine to collect in the bladder, similar to that in an obstructive episode. Stagnant urine can become concentrated which promotes § crystal formation, aggravating the risk of § mechanical obstruction (see below). Urine leakage if the bladder is not emptied due to overflow incontinence and/or detrusor malfunction (also seen in obstructive episodes). Leaking of urine can also occur due to inflammation of the urinary musculature. Loss of appetite and/or refusal to drink due to pain. Adopting unusual postures to cope with the pain. Urinating in places other than the litter box as the cat associates the pain of urination with the litter box. Licking/over-grooming the genital area. Lying on cold surfaces, such as tile floors or in showers, in an attempt to relieve pain.
Obstructive FIC ("the blocked cat") If the acute flare-up of non-obstructive FIC has not resolved itself, it can progress to an obstructive episode in a small number of cases. This is where the urethra can become partially or fully blocked. This is a particular risk for males since they have narrow urethras. Female cats have a larger urethra and rarely become blocked. The following clinical signs may be observed:
In the case of full obstruction, unproductive and painful straining with either no urine passed at all or isolated drops produced ("spotting") despite frequent trips to the litter box. Urinary retention due to incomplete voiding as a result of the obstruction. This means the bladder fills but cannot empty, causing bladder distension (the bladder will feel large and tense). Involuntary leaking of urine due to paradoxical incontinence (when drops of urine leak past the obstruction due to pressure building up in the distended bladder). Increased pain caused by stagnant urine collecting in the bladder, aggravating underlying inflammation, as well as the increasing distension of the bladder. Increased agitation and restlessness. Possible vomiting. Eventual lethargy and listlessness if a fully obstructive episode progresses, causing risk to life.
A full obstruction is a medical emergency and must be relieved by a vet immediately. Partial obstructions should also be investigated as soon as possible as they are unlikely to resolve themselves and can escalate to full obstruction. Early intervention leads to better prognoses.
Differential diagnosis of obstructive and non-obstructive cases
The clinical signs in both obstructive and non-obstructive cases can appear very similar to the owner. In particular, stranguria (when a cat strains when urinating), is observed in both cases. The differences between the two cases are discussed below. +Clinical features of obstructive and non-obstructive stranguriaProcessFrequency of urinationVolume of urinationBladder sizeSystemically unwellNon-obstructive stranguriaIncreasedDecreasedSmallUnlikelyObstructive stranguriaIncreasedDecreased to noneLargeUnlikely A vet will often distinguish between obstructive and non-obstructive cases by checking the cat's bladder. A normal, healthy bladder will be semi-full of urine and soft to the touch, like a partially filled balloon. However an inflamed bladder (suggestive of cystitis) will have thickened walls. The bladder muscles have become inflamed and irritated, provoking an involuntary urge to frequently urinate. This can manifest as the straining (i.e. stranguria) observed as the cat attempts to void. As long as the cat is able to void (even if volumes may be small), the bladder will present as "small" on examination (i.e. very little urine in it due to frequent emptying). This suggests the cat has not (yet) blocked.
However, if the bladder remains distended (i.e. full of urine), it is considered "large" and together with the obstructive clinical signs listed above, could suggest blockage. The vet will palpate the bladder in an attempt to produce a free-flowing, continuous stream of urine. If this does not occur, a potential obstruction will be suspected and further diagnostics like urinalysis, ultrasound and x-rays may be warranted. However a large bladder and/or the inability to express it is not definitive for blockage. The cat could be resisting the vet's intervention by "pushing back," due to anxiety or a desire to avoid a painful urination.
A less frequently seen intermediate case is where the bladder presents as small but is accompanied by severe straining and frequent attempts at urination. This suggests a possible intermittent spasming of the urethra (i.e. an "on-off" § functional block) which allows voiding at times when the cat is able to relax himself, but prevents it when the urethral muscles tense involuntarily again. In these instances, the vet may sedate the cat, which relaxes the entire urinary musculature, causing spontaneous urination.
Pathophysiology Feline idiopathic cystitis is above all an inflammatory process.
Non-obstructive episodes of FIC Flare-ups of FIC generally begin as non-obstructive incidents. They involve acute inflammation of the lower urinary tract but the cat is still able to urinate. The majority of cases (85%) remain non-obstructive without escalation into blockage and usually resolve themselves within seven days with or without treatment.
Causes The direct cause of feline idiopathic cystitis is unknown. It is a diagnosis of exclusion which means other possible urinary diseases which could cause bladder inflammation (e.g. feline urinary tract infections or urolithiasis) are ruled out. Research is still being pursued regarding the causes of cystitis in cats, though the following principal risk factors have been identified:
Cats predisposed to anxiety or who have a low tolerance to stressors are particularly vulnerable since stress is now considered to be a key factor in triggering acute episodes Cats who are neutered or spayed too early Cats who are younger/middle-aged (i.e. those less than 10 years old) Indoor cats and/or cats who are unable express natural feline behaviour (e.g. hunting) Cats fed a dry food diet who may be inadequately hydrated Increased body weight
Treatment of an acute episode First and foremost, the cat must be kept well hydrated with wet food/soups/broth/increased water intake. This keeps the urine dilute, reducing pain and inflammation, as well as encouraging urination to keep the bladder clear of debris thereby reducing the risk of a § mechanical blockage. Dry food must therefore be avoided. Since the underlying process is inflammation of the bladder, one of the most frequent pharmacological treatments is to administer anti-inflammatory medication. NSAIDs such as meloxicam or robenacoxib are commonly prescribed to control this (provided there are no renal or gastric contraindications). The condition is painful and analgesia (via NSAID or opiates such as buprenorphine) is essential to reduce discomfort and control further stress (which could in turn trigger further inflammation). In the case of a male cat, spasmolytics such as prazosin and/or dantrolene may also be prescribed to control painful urethral spasms and prevent the risk of a § functional blockage. Some research has suggested that prazosin is contraindicated as it leads to recurrent blocking. However this remains strongly contested on the basis of widespread anecdotal evidence showing its effectiveness if administered for at least 10–14 days. If prazosin is not prescribed, some form of anti-spasm medication must be given. In most cases this will be dantrolene. Diazepam is contraindicated as it is associated with harmful side-effects.
Since stress is considered to be a key aggravator in triggering cases of FIC, the most important non-pharmacological/non-dietary intervention is to modify the cat's environment to minimise stressors and improve general well-being (see § environmental modification below). In addition, calming supplements such as tryptophan or alpha-casozepine can also be added to food to improve mood and relaxation.
Oral supplements to reinstate the protective glycosaminoglycan (GAG) layer of the bladder (often deficient in cats suffering from FIC) may also be considered. Supplementation with antioxidants and essential fatty acids such as high quality fish oil have also been shown to reduce the severity of the episode. The veterinarian may also use a urine sample from the cat to carry out urinalysis to test for the § presence of crystals which could aggravate the condition (see below).Pawprints and Purr Incorporated. "Feline Cystitis". Feline Cystitis