Feline Idiopathic Cystitis

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, meaning the direct cause of feline cystitis is unknown; 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 no longer considered idiopathic (as a cause has been identified) and it is described as a feline urinary tract infection (UTI) or less commonly, feline bacterial cystitis. However, UTIs in cats under the age of 10 years old are very rarely encountered and whilst other specific reasons for the inflammation may be identified, in most cases it will not have an known cause and remains idiopathic. 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 in most cases (around 85%) is self-limiting, resolving itself in around a week. In a smaller number of cases (approximately 15%), 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 therefore a careful § differential diagnosis is necessary to distinguish between a suspected obstruction (which is an emergency) and a non-obstructive case (which is not).

Suspected interaction of clinical signs in FIC

Non-obstructive FIC

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 (ie there is no obstruction of the urethra). The cat's lower urinary tract is inflamed and the urethral passage may have narrowed due to swelling but it remains open and he can urinate, albeit in discomfort. Clinical signs apparent during an acute episode include:

• Frequent trips to the litter box coupled with straining as a result of an urge to void urinary waste which is irritating the inflamed bladder wall.
• Small volumes of urine usually produced.
• Sensation of incomplete voiding even once bladder is emptied.
• Blood may be present in the urine due to glomerulation or possibly Hunner's ulcers.
• Odorous urine could be exhibited.
• Irritability in personality.
• Lack of interest in normal activities.
• Hiding in a dark, quiet location (hiding is part of the cat's stress coping mechanism).
• Experiencing pain or vocalising when urinating. This may result in the cat avoiding urination due to the pain of excretion which in turn could lead to urine remaining stagnant and concentrated, further irritating the inflamed bladder wall and promoting bladder distension and possible leaking of urine due to overflow incontinence and/or detrusor atony. Concentrated urine also encourages § crystal formation, aggravating the risk of § mechanical obstruction (see below). Note that since cats are adept at hiding their pain, vocalising, crying or any other audible cue may not always be observed.
• 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 in the genital area.
• Lying on cold surfaces, such as tile floors or in showers (the cold surfaces help ease pain).

28.E2.80.9Cthe_blocked_cat.E2.80.9D.29">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, where the male urethra can become partially or fully blocked (female cats with their larger urethra do not as a rule block in this way). The following clinical signs can then be seen in addition to many of those listed above:

• 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 a) stagnant urine collecting in the bladder and aggravating underlying inflammation and b) the increasing distension of the bladder.
• Increased agitation and restlessness.
• Possible vomiting.
• Eventual lethargy and listlessness if a fully obstructive episode progresses unchecked and causes 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 will most likely escalate to full obstruction. Early interventions lead to better prognoses.

Differential diagnosis of obstructive and non-obstructive cases

Symptoms can be confusing as similar clinical signs appear in both obstructive and non-obstructive cases which is problematic as the former is an emergency and the latter is not. For example, a cat suffering from many types of lower urinary tract disease (both non-obstructive and obstructive) will strain to pass urine and can appear restless. Whilst straining does not necessarily mean a cat is "blocked", in a small number of serious cases it does. Usually in a non-obstructive case, small amounts of urine will still be passed but where there is an obstruction, no urine at all (or only isolated drops) will be produced, despite frequent, unproductive visits to the litter box. However where a cat's urination pattern can not be observed accurately (for example he voids outside or uses non-clumping litter), the position will not be clear.

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 and if the bladder is small (ie empty), it further indicates the cat cannot tolerate holding urine as it is irritating the inflamed bladder walls and therefore the cat seeks to void frequently to keep the bladder empty. Provided the cat is able to do this to obtain relief from the pain of urinary contact, it suggests non-obstructive cystitis. However, if the bladder is distended (ie full of urine) then it is clear that the cat is either unwilling (eg due to pain of excretion) or unable (eg due to blockage) to void. To determine if it is the latter (ie a medical emergency) the vet will try palpating the bladder to see if it empties without difficulty. If the bladder cannot be easily manually expressed (ie emptied) like this to produce a free-flowing, continuous stream of urine, a potential obstruction will be suspected and further diagnostics (urinalysis, ultrasound and x-rays) will usually be undertaken to investigate the cause of the obstruction. It should be said however that even an inability to express a distended bladder is not definitive for blockage as the cat may simply “push back” when palpation is attempted (ie he actively resists the vet's intervention due to anxiety or because, even though he is physically able to void, passing urine is causing intolerable pain and so he resists it). If the cat is known to be anxious and therefore possibly unco-operative in this way, gabapentin may be prescribed in advance of the examination to relieve this anxiety, as well as providing pain relief.

A less frequently seen intermediate case is where the bladder presents as normal (ie partially full) but is accompanied by straining and a desire on the part of the cat to empty. Ordinarily in the case of non-obstructive FIC, the straining would be productive, causing the cat to void repeatedly (producing small amounts of the urine each time), to ensure the bladder remains empty (ie it will present as "small" on physical examination). However the fact that the cat continues to strain in an attempt to void, but the bladder still contains some urine (ie it is not small but it is not distended either), could suggest a possible intermittent spasming of the urethra (ie 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. The vet will as usual attempt to manually express the bladder but if this does not produce a stream of urine by a (co-operative) cat, then another possible line of investigation will be to sedate the cat which will relax the entire urinary musculature. The cat should then urinate spontaneously as the sedative causes him to lose control of his urinary muscles, forcing them to relax so that urine can no longer be retained in the bladder. If he does urinate in this manner (and assuming his “normal”-sized bladder could not be easily expressed before sedation and the cat had also shown earlier signs of unproductive straining), then an intermittent functional block may be suspected.

If after suitable investigations, the episode is ultimately shown to be non-obstructive, analgesia and anti-inflammatory medication is usually prescribed to reduce discomfort and bring symptoms under control (see further discussion on treatment of non-obstructive episodes below). However if obstruction is confirmed, then catheterisation is usually the preferred treatment to relieve the blockage (see discussion of treatment of obstructive FIC below).

Pathophysiology

Feline idiopathic cystitis is above all an inflammatory process. Whilst the specific cause is unknown, it appears to be associated with complex interactions among the nervous system, adrenal glands, and urinary bladder. Environment also appears to play a role in the pathophysiology and, in some cases, is associated with clinical signs related to the gastrointestinal, cardiovascular, respiratory, nervous, integumentary, and immune systems.

Non-obstructive episodes of FIC

Flare-ups of FIC generally begin as non-obstructive incidents involving acute inflammation of the lower urinary tract but where the cat is still able to urinate.  The majority of cases (85%) remain non-obstructive without escalation into blockage and usually resolve themselves within 7 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 attacks of FIC. This includes:
  • Stress from house moving or other changes of routine
  • Stress from having conflicts with other cats or other pets in the house
  • Stress from boredom or inactivity, particularly from being kept strictly indoors
• Cats who are neutered or spayed too early
• Cats who are younger/middle-aged (ie those less than 10 years old)
• Cats fed a dry food diet (including prescription dry food) whose levels of hydration are far lower compared to cats eating wet food (this comparison takes into account moisture from all sources ie food intake and drinking water).
• 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 intensely 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 in combination with dantrolene may also be prescribed to control painful urethral spasms and prevent the risk of a § functional blockage.

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).

Within a week most cats should improve spontaneously as the inflammation subsides. However, it is essential to monitor urine output (and compare it to moisture intake) throughout the day, every day, to watch for incipient signs of blocking until the inflammation subsides and the cat returns to good health. Any presumed non-obstructive case which does not resolve itself with 7 days should be suspect for obstruction and investigated further.

28.E2.80.9Cthe_blocked_cat.E2.80.9D.29">Obstructive episodes of FIC (“the blocked cat”)

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 so that 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"):

Functional blockage

The block can be functional. This occurs when a severe muscle spasm of the urethra occurs to close it shut and the cat is unable to relax himself again to regain normal function. It is intensely painful and is triggered by the underlying inflammation, itself suspected to be caused by the stress of the condition. Effectively the cat involuntarily "blocks himself".

Mechanical blockage

A mechanical block occurs when actual physical particles obstruct the urethra. A urethral plug forms from bladder "sediment" (or "debris") which is composed of material generated from the underlying bladder inflammation (ie red blood cells, white blood cells, mucus from the bladder lining, protein) which instead of being excreted naturally, collect to form a soft toothpaste-like material called "matrix" which blocks the urethra. Matrix on its own can form a urethral plug (in which case it is called a "mucus plug") but if § crystals are present in the bladder (see below), they can coalesce with soft matrix to form a hardened urethral plug. The most common type of urethral plug (over 80%) are of this latter type ie struvite-crystalline plugs.

Interaction between functional and mechanical blockage in FIC

Both functional and mechanical blocks can negatively interact to fully obstruct the cat rapidly. In a multifactorial example, the underlying inflammation can narrow the urethral opening as well as provoking spasming to cause the walls of the urethra to close shut around a urethral plug forming in it.

The role of crystals in obstructive FIC

Crystalluria is the presence of microscopic crystals in feline urine.  These are most often struvite precipitates but other minerals such as calcium oxalate crystals are also found, albeit less frequently.  Urinary crystals are not necessarily an abnormal finding and can be seen both in cats who are healthy and those who are suffering from a urinary tract illness. Provided they are processed efficiently by the feline urinary system, they are unremarkable.  As struvite crystals tend to form in concentrated, alkaline urine, they are unlikely to accumulate to a problematic degree in the healthy, well hydrated cat which is fed a high quality meat or fish diet. This is because:

• the high moisture intake will keep urine dilute, causing crystals to dissolve, as well encouraging frequent urination to keep the bladder clear of any crystalline build-up and;
• a high quality animal protein diet should of itself naturally keep the urine mildly acidic (ideally a pH of around 6.5) which again encourages struvite dissolution (note that if excessive acidity develops for any reason, it could lead to formation of calcium oxalate crystals).

In cases of FIC however, the affected cat is not healthy. He is unwell and his urinary system is not functioning properly, and therefore he may struggle to clear crystals from the bladder as a result of the syndrome.  The inflammation, particularly in a full or partial obstructive episode, may encourage urinary retention and incomplete voiding.  This causes the urine to continually collect in the bladder and become concentrated (as it becomes stagnant) and concentrated urine encourages crystal formation.  Lack of hydration and a dry food diet exacerbates this process.  Large amounts of struvite crystals can also aggravate the discomfort of an FIC attack.  Due to their sharp edges, they can chafe an already inflamed bladder lining causing more pain and increased bleeding.  And whilst crystals (as opposed to uroliths) do not alone cause a urethral obstruction, they aggravate the risk of it since they are usually one of the components of a urethral plug which is responsible for § mechanical blockage in obstructive episodes (see above).

The nature and extent of crystal formation, together with urine pH, can be ascertained with a urinalysis to determine if there are any areas of possible concern.

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, to drain the backed-up urine and flush the bladder out of any sediment and/or crystals. This is an invasive, delicate procedure which will require either heavy sedation or general anaesthetic. The cat may then be hospitalised with the catheter in place and hydration administered intravenously to encourage healthy urination and good kidney function for up to 3 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).

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 due to tenderness). 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 only) 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 or Vitamin C) 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 (possibly triggering recrudescence ie a further acute attack), as well as encouraging calcium oxalate crystal formation. 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 overall, general hydration from any wet food the cat finds palatable. Dry food of any sort (including prescription dry food) must 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.

Secondary bacterial infection (UTI) after an obstructive episode

Whereas primary feline urinary tract infections are very rare in younger male cats, when a cat suffers an obstructive episode of FIC which has involved catheterisation and/or the symptomatic presence of crystals, then a secondary urinary tract infection becomes more likely as a follow-on complication. The symptoms of bacterial infection in the lower urinary tract are very similar to those for non-obstructive FIC (ie straining, blood in urine etc) and a urine test with cultures will be needed to detect if an infection is present. Treatment is usually effective with antibiotics once the result of the urine culture identifies the precise bacteria involved in the infection. D-mannose is also used by some pet owners as a natural alternative to antibiotic treatment although this may be less targeted and specific than prescribed antibiotics following a urine culture.

Ongoing management of FIC

Since feline idiopathic cystitis is commonly known to reoccur, ongoing precautions need to be taken to avoid relapse.

Importance of hydration

The most important preventative measure is to improve the overall moisture intake with any high quality wet food which is found to be palatable by the cat. Good hydration is essential for good urinary tract health. It militates against inflammation and dilutes the urine which causes less pain should it come into contact with an irritated bladder wall during an acute attack of FIC. In addition the well hydrated cat is unlikely to degenerate into full blockage, as he will produce large amounts of urine which will flush out any bladder sediment and/or crystals before it can accumulate. Crystals in any case are unlikely to form to a problematic degree in the dilute, mildly acidic urine produced by a cat eating a quality wet, animal protein diet. Wet prescription cat food which has been specially acidified may be also recommended to reduce the likelihood of struvite crystal formation which can be problematic if allowed to accumulate in significant quantities. However it is not essential in the absence of urolithiasis and is very much secondary to the first priority of general hydration.

As domestic cats are descended from their desert-inhabiting ancestors, they instinctively seek moisture from their prey. High quality wet food is the most natural way therefore to hydrate a cat as drinking water from a bowl is arguably species-inappropriate since anatomical limitations in the cat's tongue restrict the amount of water they can ingest this way. Drinking still water from a bowl (particularly tap as opposed to rain water) is often a last resort for many cats and some may avoid it altogether. A quality wet food diet will therefore be most effective in ensuring sufficient moisture intake and will always be more effective than dry food in hydrating a cat, even when any additional moisture intake from drinking water is taken into account. Cats at risk of urinary disease must therefore avoid dry food as much as possible.

The nutritional profile of a good quality diet will include a high meat content, high levels of moisture, minimal fillers and minimal carbohydrate content (since cats cannot digest carbohydrates efficiently, this could cause digestive inflammation, thus stressing an already weakened immune system in a cat suffering from FIC).

Supplementing wet food with antioxidants and essential fatty acids such as high quality fish oil have also been shown to reduce the severity and recurrence of FIC episodes.

Environmental modification

Together with hydration, improvements to the cat's environment have been shown to prevent relapses. Reducing stress and encouraging natural feline behaviour (particularly for indoor cats) is essential. Suggested methods include:

• No sudden disruption to routine or changes in a cat’s environment. Cats are most comfortable in familiar territory, operating within a predictable schedule. Even a short delay to a cat’s usual feeding times for example has been shown to elevate stress levels.
• Outdoor visits (supervised in the case of indoor cats) will encourage sensory stimulation and defeat boredom which could lead to stress.
• Window sill perches (particularly if they look out onto a natural landscape with wildlife and birds) provide important visual stimulation, particularly for cats who have no outdoor access. Ideally the perches should be affixed to windows which provide good visibility of the surrounding outdoor space (windows on lower floors of a building work better therefore than those on floors which are too high up). Perches should be affixed at a variety of locations to offer diverse vantage points.
• Olfactory enrichment with indoor cat-safe plants (e.g. cat grass, catnip, silver vine or cat thyme) can again replicate a pleasing, natural environment indoors.
• Maintaining close contact with owners and avoiding extended periods of isolation to prevent separation anxiety. This is particularly important for rescued strays or abandoned cats who have since been re-homed in an environment they perceive as safe.
• Play with owners in short bursts de-stresses a cat and stimulates positive neural activity.
• Regular rotation and replacement of cat toys.
• A wet-only feeding pattern which imitates a cat’s natural instinct in the wild (ie little and often). Incorporating mental stimulation can be considered with the use of feeding puzzles and changes to the location of the feeding bowel to stimulate the hunting instinct (dry food must not be included in the diet however). Cats usually enjoy variety in their food but will avoid new foods if anxious or if it reminds them of a stressful episode (eg a visit to the vet). Therefore new foods must be introduced with care and familiar foods always available during a changeover period to allow the cat to make its own choice.
• Cats move vertically as well as horizontally so cat trees and high-level hiding places encourage natural movement.
• Free access to both warm and cooler zones in the home.
• Safe, enclosed, quiet sleeping areas (such as an igloo bed) will allow a cat to retreat to safety if anxious and have been shown to reduce stress.
• Acoustic startlement (e.g. loud noises from washing machines, vacuum cleaners, building work) should be minimised, at least in a period of convalescence, to ensure the cat is not frightened by environmental disturbance. Adverse reactions to sudden loud noises can be mitigated by radio or television playing in the background.
• Litter tray availability and hygiene is essential. Easy, unfettered access to clean litter boxes (with litter than can identify any unusual urinary behaviour such as clumping litter) is essential if the cat cannot void outside (cats voiding outdoors do not show a high incidence of relapse).
• Since antipathy between other cats or pets is also a major source of stress, facial pheromone treatments or spatial separation between unco-operative pets may need to be considered. Such behaviour may not always be obvious and owners need to observe interaction (and minute changes of behaviour) between pets carefully to detect even the smallest signs of discord, for example at sunrise when owners may be asleep but cats are usually awake.

Surgical intervention for refractory cases

For recurrent cases of FIC in male cats where blockage is a risk, and dietary and environmental modifications have not prevented relapse, a last line of treatment to prevent future obstruction is surgery to widen the male urethra. This is called Perineal Urethrostomy (PU) but brings with it other risks and should therefore only be considered once all other options have been exhausted.