Urocystoliths associated with inflammation of the lower urinary tract were identified on the basis of the history, physical
examination and laboratory test results.
Initial diagnostic plans
To evaluate the entire urinary tract for evidence of uroliths and other possible causes of inflammation, survey abdominal
radiography and double contrast cystography were planned.
Survey radiographs of the abdomen revealed two elliptical, radiodense uroliths in the bladder lumen (Figure 1). Double contrast
cystography revealed slight thickening of the bladder wall and irregularity of the bladder mucosa (Figure 2).
Figure 1: Survey lateral abdominal radiograph of a 4.5 year-old spayed female domestic shorthair cat illustrating tow radiodense
On the basis of available data, what is the probable mineral composition of the uroliths? The following observations were
interpreted to indicate that the urocystoliths were composed of sterile struvite:
- Radiographic density of the uroliths,
- Struvite crystalluria,
- Alkaline urine pH,
- Negative in vitro culture of urine for aerobic bacteria.
Medical dissolution of uroliths
How would you manage this patient if it were you, a family member or your cat? Would you recommend surgery, medical dissolution
or a combination of the two? In a prospective clinical trial of medical dissolution of feline struvite urocystoliths in 20
cats performed at the Minnesota Urolith Center, consumption of a magnesium restricted diet designed to promote formation of
acid urine (Prescription Diet Feline s/d; Hill's Pet Nutrition Inc.) resulted in dissolution of struvite uroliths in four
to five weeks (JAVMA 196: 697-733, 1990). After informing the client of the benefits and risks associated with surgery and
medical management, the client requested medical management.
Figure 2: Lateral view of a double contrast cystogram illustrating the urocystoliths described in Figure 1.
Accordingly, the owners were instructed to feed the canned formulation of Feline s/d in sufficient quantity to maintain stable
body weight. Plans were to continue this regimen of therapy for one additional "insurance month" following survey radiographic
confirmation of urolith dissolution.
The owner indicated that the clinical signs of hematuria and dysuria gradually subsided during a two-week period following
initiation of dietary therapy. Thirteen days after initiation of therapy, physical examination revealed no abnormalities.
Evaluation of a urine sample collected by cystocentesis revealed that the urine specific gravity was 1.026 and the pH was
6.5. Crystalluria was not observed. Although the urine was yellow in color, hematuria was detected by microscopic examination
of urine sediment. These findings (acid urine pH, no struvite crystalluria, and reduction in specific gravity) indicate owner
and patient compliance with dietary recommendations. Survey radiography revealed that the urocystoliths were approximately
one-third their original size (Figure 3). The owners were shown the pre- and post-treatment radiographs to reinforce the need
for continued therapy, and to praise them for compliance with management recommendations. They were advised to continue therapy
with the calculolytic diet.
Figure 3: Survey lateral abdominal radio-graph of the cat described in Figure 1 obtained 13 days after initiation of management
with a struvitolytic diet. The urocystoliths are about one-third their premanagement size.