The client was advised to continue therapy with the struvitolytic diet and to give an oral broad-spectrum antibiotic known
to be excreted in high concentrations in urine for seven days following double-contrast cystography to minimize the possibility
of urinary catheter-induced bacterial UTI.
Figure 5: Survey abdominal radiographs of the cat described in Figure 1 obtained seven weeks after initiation of dietary therapy.
There are no radiodense uroliths in the urinary tract.
The cat was evaluated three weeks later (seven weeks after the onset of therapy with the struvitolytic diet). During the three-week
interval between evaluations, the cat remained asymptomatic. Evaluation of a urine sample collected by cystocentesis revealed
no abnormalities (specific gravity = 1.052; pH = 6.0). Survey abdominal radiography and double-contrast cystography revealed
no evidence of the urolith or the vesicourachal diverticulum (Figures 5 and 6).
Figure 6: A double-contrast cystogram of the cat described in Figure 5. There is no evidence of urocystoliths or of a vesicourachal
diverticulum (see Figure 4).
What is the likelihood that the vesicourachal diverticulum will recur at a later date?
In our experience with more than 50 cases, there have been no recurrences of vesicourachal diverticula in cats.
What is the likelihood of recurrence of struvite urocystoliths?
The general consensus based on clinical experience is that recurrence is unpredictable. Therefore, the client was advised
of the availability of diets designed to control several known risk factors associated with formation of struvite uroliths.
The need to periodically evaluate the effects of these diets on urine pH and crystal formation was emphasized. Periodic evaluation
of the cat by physical examination, urinalysis and survey abdominal radiography during the next 10 months revealed no evidence
of lower urinary tract disease.
Key points to recall
1. Several diseases may cause or complicate feline lower urinary tract diseases.
2. Survey abdominal radiographs and/or double-contrast cystography are essential to consistently detect feline uroliths.
3. The mineral composition of uroliths may be predicted on the basis of knowledge of diet history, urine pH and crystalluria.
4. Compliance with consumption of a magnesium-restricted diet formulated to acidify urine typically results in struvite urocystolith
dissolution in four weeks.
5. Vesicourachal diverticula often heal spontaneously following eradication of the underlying cause.
6. The efficacy of diets designed to minimize risk factors for recurrent urolithiasis should be evaluated by timely reevaluation
of the patient (especially compliance with diet recommendations), periodic examination of fresh urine sediment and determination
of urine pH with a pH meter.
7. The efficacy of dietary dissolution of sterile struvite urocystoliths indicates that this therapeutic strategy is a standard
Dr. Osborne, a diplomate of the American College of Veterinary Internal Medicine, is professor of medicine in the Department of Small
Animal Clinical Sciences, College of Veterinary Medicine, University of Minnesota.