By Reinrie Egberink* and Amanda Klein.
Feline lower urinary tract disease (FLUTD) is common in small animal practice, with morbidity between 1-6%.
To diagnose and treat successfully, a thorough and systematic approach is necessary.
A thorough history must determine if there have been any previous episodes of urinary obstruction, surgery or trauma.
Also, specific information regarding behaviour (urinating in inappropriate places, stress), haematuria, dysuria,
pollakiuria should be noted.
On clinical exam, the most obvious clinical finding is collapse and coma in the male cat from urethral obstruction
and subsequent metabolic dysfunction. Other findings on physical examination include a thick and firm bladder wall.
If obstructed, the bladder will be very large. Close inspection of the penis may show urethral plugs or uroliths.
Laboratory tests should first include bloods in cases of urethral obstruction to test for azotaemia, hyperphosphataemia,
and hyperkalaemia.
Usually however, urine examination is the most essential tool in the work up of the pathophysiology behind FLUTD.
It should be done routinely even if the cause seems obvious, and in some cases may be needed more than once.
The sediment may reveal haematuria, proteinuria, pyuria, crystalluria, bacteriuria, funguria, or ova of capillaria.
Obtaining the urine can be difficult however especially if cystitis is present, because the frequent passing of
urine means the bladder is often nearly empty. Manual pressure of the bladder, or very skilful cystocentesis can
be employed by a veterinarian in order to obtain the sample, or awaiting urine to be voided by the cat in to a tray.
Obtaining urine by the cat voiding its bladder is common, and has its benefits. It is the only reliable way of
testing for haematuria. Also, it is less stressful collecting urine from the tray than handling the cat.
Unfortunately litter tray samples are often soiled or the urine composition is changed by the kitty litter.
The cleaner the sample is, the more reliable analysis is, and so clean non absorbing cat litters such as katkor
are excellent in the work up of an FLUTD case. Clients collecting urine at home must be informed that the sample
should be delivered back to the clinic as soon as possible. In 8 hours the pH may increase, any struvite crystals
can dissolve back out solution.
Survey or contrast radiograhy is a common method of detecting radiodense uroliths or urethral plugs.
Contrast cystography can also show morphological defects such as urethral strictures or urachal diverticula, and tumours. Double contrast cystography can be used to detect small or radiolucent uroliths, blood clots, and inflammation of the bladder wall. Thickening of the bladder wall may be caused by inflammation or neoplasia. Biopsy of the bladder may enable characterisation of the inflammation but is not routinely needed. Bladder ultrasound can also be used to
detect or exclude uroliths or urethral plugs.
Urolithiasis accounts for more than 30% of FLUTD cases. Therefore, microscopic urinalysis for detecting uroliths
in urine is of utmost importance, and if found the composition of uroliths should always be determined.
Detecting uroliths in urine does strongly indicate that this is the cause of the FLUTD and should be addressed.
However, the extent of crystals in the urine required to inflict significant damage to the mucosa is debateable,
and hence it is possible to find small amounts of crystals in the urine without necessarily being a significant
contributing factor to the FLUTD.
Bacterial infection of the urinary tract occurs in less than ten percent of cases. Culture of urine is only
beneficial in ongoing recurrent cases of FLUTD, and is more common in older cats. Note that if the time period
between collection of urine and arrival at the laboratory is too long, false negative results may occur due to
storage and transportation. Samples for culture and sensitivity should always be collected by cystocentesis.
A more accurate measure of bacterial problems is microscopic examination of the urine sediment for leukocytes and
bacteria. This is preferable to evaluating leukocyte numbers on dipstick as this can often give false positive results.
Morphological defects and tumours are very rare.
Another theory to the cause of FLUTD, is that a deficit in the protective lining of the bladder may occur under stress.
Despite extensive work ups, no discernable cause can be found in over 50% of FLUTD presented cases, and idiopathic
cystitis becomes an exclusional diagnosis. Regardless, the work up involved getting to this stage is heavily
centred around urinalysis. Hence, obtaining urine samples with ease and minimal stress, and obtaining quality
urine samples is paramount to the successful work up of the case.
* Vet by Rein Vet Products, e-mail info@katkor.com
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