Research Updates: How often do uroliths really recur in cats?
A total of 4,435 cats were included in the study. Regarding the first uroliths analyzed, 54% of the identified cats (n = 2,393) had calcium oxalate uroliths, 41.1% ( n= 1,821) had magnesium ammonium phosphate uroliths, and < 1% (n = 221) had ammonium urate uroliths. Almost all calculi (95.5%) were removed from the lower urinary tract (bladder or urethra).
Urolith recurrence was determined based on repeat urolith analysis in 5.5% of cats (n = 242) during the six-year study period. The frequency of recurrence was 7.1% (first recurrence), 0.6% (second recurrence), and 0.1% (third recurrence) for calcium oxalate uroliths; 2.7% (first recurrence) and 0.2% (second recurrence) for magnesium ammonium phosphate uroliths; and 13.1% (first recurrence) and 4.1% (second recurrence) for ammonium urate uroliths. Urolith composition at the time of recurrence was the same as the initial uroliths in almost all cases, ranging from 83% to 96% depending on the mineral type. Mean interval to first recurrence was between 1.8 and 2.4 years. Older cats initially diagnosed with calcium oxalate or magnesium ammonium phosphate calculi were more likely to have recurrent uroliths identified than younger cats were.