lower urinary tract disease (FLUTD) describes a collection
of conditions that can affect the bladder and/or urethra of
cats. Unfortunately, the clinical signs are rarely indicative
of a particular disease. While there are many conditions that
can result in signs of FLUTD (see below) the vast majority
of cases are idiopathic (ie, we cannot find the cause).
signs of FLUTD
with FLUTD usually present with signs of difficulty and pain
when urinating, increased frequency of urination, blood in
the urine, urination outside the litter-box and in inappropriate places, or even complete
obstruction to urine outflow. Some cats show only behavioural
change, loss of litter-box training and/or aggression.
annual incidence of FLUTD in British cats is believed to be
around 1 per cent. While the condition can be seen in cats
of any age, it is most frequently seen in middle-aged, over-weight
cats, which take little exercise, use an indoor litter-box,
have restricted access outside and eat a dry diet. Persian
cats appear to be predisposed. FLUTD occurs equally in male
and female cats; however, neutered cats are more susceptible,
and the risk of urinary tract obstruction is greatest in males.
of non-obstructive FLUTD
Non-obstructive idiopathic cystitis
of obstructive FLUTD
stones + bacterial infection
Feline idiopathic cystitis (FIC)
the majority of cases of FLUTD no underlying cause can be
found. However, while research over the last 30 years has
failed to find a consistent cause, a recent hypothesis has
suggested that FIC may result from alterations in the interaction
between the nerve supply, the protective (glycosaminoglycan
[GAG]) layer that lines the bladder, and the urine (see Figure
1. Diagram showing how the nervous system may be able
to induce/exacerbate inflammation in FIC (neurogenic
is now known that certain nerves within the bladder can be
stimulated, either by the brain (in response to 'stress'),
or by local triggers within the bladder (eg, inflammation,
bladder stones, concentrated urine, infection, etc). Regardless
of how these nerves are stimulated they release certain neurotransmitters,
which can then act to induce and/or exacerbate local pain
and inflammation. Where inflammation is triggered by the nervous
system it is termed neurogenic inflammation.
Stress plays a very important role in triggering FIC and it has been shown that cats that are predisposed to getting FIC show exaggerated arousal and response to stress. However, they are then unable to take control of their environment (ie, they cannot run away, do not tend to hiss, etc); instead they tend to hide much of the time.
thin layer of protective mucus lines the inside of the bladder.
This layer helps to prevent bacteria and crystals from sticking
to the bladder wall. It has been suggested that defects in
this protective layer may result in increased bladder wall
permeability, allowing noxious substances within the urine
to cause inflammation. It has been shown that some cats with
FIC have reduced levels of GAG within this protective layer.
While it is not known whether or not the defect is actually
caused by the inflammation, its presence is believed to exacerbate
stones (uroliths) can vary in their composition, with struvite
and oxalate forms being most common in cats. Over the last
few years the pet food companies have focused on designing
diets that help to dissolve struvite stones. Unfortunately,
while this has resulted in a decline in the incidence of struvite
stones there has been an increase in oxalate stones. Unfortunately,
oxalate uroliths are not dissolvable in cat urine, and so
must be removed surgically.
plugs are of particular importance because they can cause
urethral obstruction. They are composed of varying combinations
of a protein matrix (various proteins and cells from the bladder
and blood) and crystalline material (most typically struvite).
The protein matrix is believed to 'leak' from the bladder
wall as a result of inflammation. The cause of this inflammation
may be neurogenic, idiopathic, or secondary to infection,
cancer or bladder stones. Thick protein matrix may cause urethral
obstruction without evidence of crystalluria (crystals in
the urine). However, where crystalluria is also present, the
crystals may become trapped within the matrix, and add to
the obstruction. It is therefore the protein matrix that is
of primary importance, rather than the presence of crystals
far, no bacterial, fungal or viral organisms have been consistently
shown to cause FLUTD. However, it is still possible that an
organism that is very difficult to grow could be involved.
Bacterial infection is a very rare cause of FLUTD. Where it
is seen, it is usually secondary to veterinary intervention (ie, placing a urinary catheter),
bladder stones, an anatomical defect, or cancer. Older cats,
particularly those with renal failure, have an increased risk
of bacterial infection. However, FLUTD is rarely seen in cats
of this age-group.
different causes of FLUTD may occur individually, or in various
interacting combinations (Figure 2). For example, the formation
of urethral plugs may result from concurrent, but not necessarily
related, disorders, ie, the simultaneous occurrence of urinary
tract inflammation and crystalluria. While obstruction most
typically results from the formation of urethral plugs, it
may also be caused by the passage of small bladder stones,
or from pain-induced urethral spasm. Although, inflammation
without crystalluria can result in obstruction with protein
matrix, it more typically causes bloodstained urine and signs
of pain when urinating. While crystalluria is usually clinically
silent, if persistent, it may predispose to the development
of bladder stones, and these, in turn can lead to urethral
obstruction, and bladder inflammation.
2. Flow diagram illustrating how interaction between
urinary tract inflammation and urine crystals can
lead to different clinical presentations.
Urinary tract inflammation may be neurogenic (triggered
via the nervous system), idiopathic (cause unknown),
or secondary to infection, cancer or bladder stones.
of FIC is made by exclusion of all other causes of FLUTD.
A practical, step-wise, approach is used. It often includes
taking blood samples to rule out systemic disease (ie, generalised disease such as kidney failure or diabetes), followed
by collection of a urine sample. The urine will be assessed
for its concentration (specific gravity), and for the presence
of crystals, protein, red and white blood cells, and bacteria
(infection). Taking abdominal radiographs, performing contrast
bladder studies, and/or ultrasound examination of the bladder
may then be performed.
no physical cause can be found it may be thought to be a purely
behavioural problem. However, if the cat is not currently showing
signs of FLUTD repeating the investigation when the cat is
showing signs may reveal more obvious disease. It is interesting
to note that many cats which are believed to have a purely
behavioural problem have a history of having had blood in their urine at some time in
cases of non-obstructive FLUTD are self-limiting; usually
resolving within five to 10 days. However, most affected cats
have episodes of clinical signs, which recur with variable
frequency. The recurrent episodes generally tend to decrease
in frequency and severity over time. Despite the likelihood
of spontaneous resolution, treatment is recommended for a
number of reasons:
is very painful and distressing to the cat.
with FIC may self-traumatise their perineal region (the
area below their tail).
with FIC may stop eating.
cats with FIC are at risk of developing urethral obstruction,
which can be fatal.
with FIC may develop behavioural changes, become aggressive
to their owners or other cats within the household, or
may lose their litter-box training.
a cat with FIC is very distressing to the owner.
few treatments for FLUTD have been investigated by well-controlled
experimental studies. Most recommendations are therefore based
on uncontrolled clinical observations and personal opinion.
Also, since FLUTD is usually self-limiting, many treatments
may appear to be effective, when they actually have no positive
effect. All treatments should therefore be considered with
more drugs are tried, the list of those that are either unhelpful,
or even harmful, is growing. Of those treatments that have
been critically assessed corticosteroids and certain antibiotics
have been shown to have no beneficial effect, except in those
rare cases where bacterial infection is present and antibiotics
are actually required.
list of medications and interventions that have been considered
for the treatment of FLUTD is far too extensive to be included
in this article. This paper therefore describes the current most successful current approach to the management of FIC, which is aimed
at addressing the factors that are believed to underlie the disease;
ie, the nature of the nerve supply into the bladder, the
content of the urine, and the protective GAG layer.
1. Reduce stress
plays a key role in FIC; it has been identified as a 'flare
factor' that can precipitate a recurrence of clinical signs.
Identified stressors include abrupt changes in diet, environment,
weather, overcrowding, owner stress, or the addition to the
household of new pets or people. Stress associated with urination
can be particularly significant, eg, an unsuitable position
or content of the litter box, competition for the litter box,
aggressive behaviour by other cats while the cat is trying
to use the litter box or when urinating outside, etc.
is essential to reduce the level of stress to which the cat
may be exposed. Providing a safe, clean area in which the
cat can urinate, reducing overcrowding or bullying, and reassuring
the cat as much as possible may achieve this. Use of Feliway (Ceva) (a synthetic feline pheromone) as a plug-in 'air freshener' can also help reduce anxiety. In severe cases it can be helpful to ask for your cat to be referred to an animal behaviour counsellor.
Alter the content of the urine
the diet is the easiest way to modify the urine. Previously,
much interest has been placed on changing the acidity, magnesium,
and calcium content of the urine. However, it is now believed
that the single most important factor is the rate of water
turnover. The aim is therefore to increase water turnover
and dilute any noxious components within the urine. Rather
than altering the content of a dry diet, it makes much more
sense to simply feed a wet one! Thankfully, a number of diets are now available that are specially designed to increase water turnover despite being dry diets; so those cats that will not eat wet food can now be treated more appropriately.
diet to canned food or moisten dry food.
free access to water and encourage the cat to drink.
not feed an acidified diet if the urine is acid and struvite
uroliths are not a problem. Long-term
use of highly acidified diets can be very harmful.
Repair the protective GAG layer
theory, therapy to replace the GAG layer should be beneficial.
It relies on the assumption that GAG supplements gain access
to the bladder and attach to the defective bladder lining.
GAGs may also be of benefit because of analgesic ('pain killing')
and anti-inflammatory properties. However, while these compounds
have shown some positive responses in humans with interstitial
cystitis, controlled studies in cats are currently lacking.
From human studies, it appears that there are differences
in the relative efficiency of different GAGs to produce positive
effects, and the same is likely to be true in cats.
controlled studies have not yet been performed, some cats do appear to derive benefit from using GAG supplementation. Supplements can be given by mouth
or subcutaneous injection. Supplementation
can begin with a higher dose at the time of initial presentation
and then be reduced to a maintenance level.
owners may notice that some cats show mild signs before the
onset of an episode of FIC. The duration of these signs may
vary from a few days to a few hours. Signs may include increased
grooming of the hind-end, or inter-cat aggression initiated
by the FIC sufferer. These signs may relate to increasing
pain. The instigation of increased reassurance, feeding wet food, use of Feliway, etc, at this time may help to reduce the
severity and duration of the episode, or prevent it from occurring
altogether. This approach can also be used if a stressful
episode is anticipated, (eg, a visit to the vet, a stay in
a cattery, builders in the home, etc).
Relief of urethral spasm
urethral spasm has been shown to be causing a problem specific
spasmolytic drugs may be beneficial. They act by causing relaxation
of the muscles within the urethra.
antidepressants (eg, amitriptyline) have been used in some
very severe or chronic cases of FLUTD. They have been found
to be beneficial in the treatment of humans with interstitial
cystitis, and in a number of cats with FIC; however, they
should always be used with caution. They act as anti-depressants,
and also have direct effects on the bladder where they can
increase bladder capacity, and have anti-inflammatory, and
'pain killing' properties.
Analgesia ('pain killers')
some 'pain killers' may reduce the severity of the pain, they
are rarely sufficient to significantly reduce the clinical
signs of FLUTD.
is important to note that all current treatments for FLUTD
are merely palliative! The best results are gained by instigating
a number of changes, ie, reducing stress, feeding a wet diet,
replacing GAGs and, if necessary, relieving urethral spasm
or giving tricyclic antidepressants. In the majority of cases
this, when tailored to the individual cat, will reduce or
prevent further clinical signs.
Updated November 2008