Bladder Problems In Cats
By: Peter G Knapp MRCVS - Website: E-VeT
FLUTD, FUS, Cystitis, Interstitial Cystitis, Blocked bladders.
FLUTD (feline lower urinary tract disorder) took over from the previous designation of FUS (feline urological syndrome) several years ago. The condition is a syndrome as opposed to an exact disorder i.e there appear to be several subdivisions and alternate presenting signs for this from actual 'blocked cats' where particularly in the male cat with a longer urethra a plug of protein, exudates and crystalline material irritates and obstructs due to associated spasm so that the penis cannot pass urine.
In mild cases the presenting signs may just be those of cystitis, pain on urination (dysuria) and frequency and some cases may be presented as inappropriate urination problems around the house.
In the past special diets have been the mainstay for therapy with the theoretical ideal being a diet that produces and acid urine (correct for the cat) to help re-dissolve any crystals and keeping mineral levels at nutritional requirements rather than above to also help.
However most feed manufacturers are fully aware of this requirement and standard commercial diets really ought to be adequate as a preventative. It is only in those cases where specific crystal types have been identified that there is justification for moving to diets deliberately designed as mineral deficient and that should adjust acidity (pH) to even lower levels. Paradoxically this approach may actually help form a different class of crystal in some individuals and should not be used without prior urinalysis and subsequent checks since the pH push may change the type of crystal formed.
Treatment for this syndrome really depends on the presentation. In cases of dysuria but adequate passage of urine there is less urgency. In those cases where there is blockage then the case is urgent to an emergency. The cat that cannot pass urine will go down fast. Total obstruction and failure to remove waste is often associated with dangerous elevations of potassium ions (K+) and toxicity can prejudice the patient's anaesthetic risk. Obstructed cats may be treated in two ways.. if fit for anaesthesia then an attempt to remove the obstruction. If not fit for anaesthesia then options include bladder drainage by needle (cystocentesis) or an emergency approach to reducing K+ levels.
As soon as bladder pressure is reduced then large amounts of urine will be formed and such cystocentesis approaches may need frequent repetition and monitoring.
Where the patient is either amenable to manipulation or able to take anaesthesia then any approach to unblocking these cats should be made with great respect for the inflamed urethra. It remains controversial whether un-blockage should be followed by catheterisation since that may also aggravate irritation of the urethra and spasm. That remains one of many dilemmas for the clinician and judgement depends on how easily the case is unblocked and inflammation caused during that process.
My personal preference is to anaesthetise cases if possible and then gently 'masturbate' the cat while applying modest pressure to the bladder; many cases will shoot out that urethral plug easily. Next level is to irrigate the tip of the penis using an i/v catheter when it is possible to introduce the catheter tip into the tip of the penis and back flush. Again many clinicians will use buffered solutions to use acidity for re-dissolution (Walpole's buffer at pH 4.5). I usually start with sterile water since the aim is to avoid inflammation. If this and further massage fails then the next step is to 'balloon' the end of the penis by insertion of the i/v catheter and hold the penis tip around it, apply pressure via a syringe and then withdraw catheter quickly.. this method often allows a progressive back-flushing of the urethral contents. Above all else avoid early catheterisation which may force material into the urethral lining.
A subset of these cases may be associated with profound protein secretions in the bladder and the production of a mass of jelly-like material incarcerating crystalline elements and the bladder may not drain. While uncommon this does leave one with consideration of surgical opening of the bladder in unresponsive cases. Prior to such measures and indeed after successful emergency treatment the ideal is both radiography and ultrasound of the bladder and kidneys.
Some crystal types may not show on standard plain radiographs and ultrasound, if available, is an excellent tool for identification of crystals and proteinaceous jelly masses; quite apart form the ability to detect other complications such as bladder neck tumours or actual bladder stones. During ultrasound it may help to roll the cat and see a snowstorm or crystals gravitating around.
All cases of FLUTD should be subject to urinalysis. Cystocentesis as a method of collection avoids contamination and gives a fresh sample. Some patients with interstitial cystitis may be aggravated by eve the simplest cystocentesis puncture. Needle sizes should be kept at 23g or below. I have seen punctures with even 21g needles continue to 'leak'. Any sample should be analysed fresh. Refrigerated or older sample will often crystallise and give false responses and may suffer bacterial growth. The incidence of bacterial infection is probably much lower than generally assumed and crystal formation may also be less relevant that previously believed (small amounts of crystal may also be normal).
Examinations should include straight 'wet preps', spun samples to look at sediment and also spun, dried and stained samples. If bacteria are involved then they are usually manifest in large numbers. Any cases under treatment should have repeat samples run and any cases treated empirically but still showing alkaline urine when on diets such as s/d should be re-evaluated. Failure to produce acid urine on s/d must imply either bacterial infection of a buffering effect from persistent crystals or failure by the owner to follow instructions.
The simplest approach to any treatment for FLUTD is fluids, fluids, fluids. Most cases will respond just by owners having the tenacity to force oral fluids into their pet to keep that urine dilute re-dissolve any crystalline material and flush out any contamination.
Current belief is that most unresponsive cases are due to an interstitial cystitis; an inflammatory change within the bladder wall that may lead to ulceration and loss of integrity of the lining proteins. These glycosaminoglycans protect the bladder from irritation by urine itself.
The cause of interstitial cystitis remains controversial. Response to amitryptilline has lead some folk to speculate that pain related endorphin secretion may aggravate this state and lead to a 'vicious circle' but equally amitryptilline has anti-inflammatory properties beyond it's psychoactive effects. At this time it remains the mainstay of therapy for proven cases of interstitial cystitis at doses from 2-12 mg per cat often just once daily (evenings) or sometimes twice daily. Side effects include sedation and 'spacing out' and doses need to be pitched to provide relief without these effects.
Many cases require intermittent life-long treatments.
Other treatments include the use of drugs such as pentosan polysulphate sodium injections (Cartrophen) to stimulate glycosaminoglycans production and presumably there may be some value in using shark cartilage supplements in the same way. Antibiotic responses may be valid or may just be a reflection that some antibiotics actually have immunosuppressive or anti-inflammatory properties too.
In the immediate post-obstruction cases there is legitimate reason to use profound anti-inflammatory medications such as corticosteroids or megeostrol acetate (Ovarid, Ovaban) to prevent urethral spasm. Again some cases may spontaneously unblock with repetitive cystocentesis and such anti-inflammatory medications.
Problem cases should be totally worked up, bloods, plain and contrast radiography including intravenous dye excretion rads and double contrast bladder radiographs as well as ultrasound of bladder and kidneys looking for any causes of a reservoir or focus for infection or inflammation. Such cases may also have surgical approaches to the bladder for biopsy and to identify any urethral stenoses (narrowing).
Cases of repeated penile obstruction may be managed by penile urethrostomy (resection, amputation) to access the wider urethra proximally as a preventative.