Evaluation of trends in urolith composition in cats: 5,230 cases (1985-2004).
OBJECTIVE
To determine trends in urolith composition in cats.


METHODS
Retrospective case series.


METHODS
5,230 uroliths.


METHODS
The laboratory database for the Gerald V. Ling Urinary Stone Analysis Laboratory was searched for all urolith submissions from cats from 1985 through 2004. Submission forms were reviewed, and each cat's age, sex, breed, and stone location were recorded.


RESULTS
Minerals identified included struvite, calcium oxalate, urates, dried solidified blood, apatite, brushite, cystine, silica, potassium magnesium pyrophosphate, xanthine, and newberyite. During the past 20 years, the ratio of calcium oxalate stones to struvite stones increased significantly. When only the last 3 years of the study period were included, the percentage of struvite stones (44%) was higher than the percentage of calcium oxa-late stones (40%). The most common location for both types of uroliths was the bladder. The number of calcium oxalate-containing calculi in the upper portion of the urinary tract increased significantly during the study period. The number of apatite uroliths declined significantly and that of dried solidified blood stones increased significantly, compared with all other stone types. No significant difference in the number of urate stones was detected.


CONCLUSIONS
The increasing proportion of calcium oxalate uroliths was in accordance with findings from other studies and could be a result of alterations in cats' diets. However, the decreased percentage of calcium oxalate calculi and increased percentage of struvite calculi observed in the last 3 years may portend a change in the frequency of this type of urolith.
Cannon
Allison B
AB
Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
Westropp
Jodi L
JL
Ruby
Annette L
AL
Kass
Philip H
PH
D000367:Age Factors; D000821:Animal Feed / Q000009:adverse effects; D000818:Animals; D001947:Breeding; D002129:Calcium Oxalate / Q000032:analysis*; D002130:Calcium Phosphates / Q000032:analysis; D002371:Cat Diseases / Q000175:diagnosis / Q000453:epidemiology* / Q000601:surgery; D002415:Cats; D005260:Female; D017616:Magnesium Compounds / Q000032:analysis*; D008297:Male; D010710:Phosphates / Q000032:analysis*; D012189:Retrospective Studies; D012737:Sex Factors; D000069877:Struvite; D014514:Ureteral Calculi / Q000737:chemistry / Q000175:diagnosis / Q000453:epidemiology / Q000662:veterinary*; D052878:Urolithiasis / Q000175:diagnosis / Q000453:epidemiology / Q000601:surgery / Q000662:veterinary*
D002130:Calcium Phosphates; D017616:Magnesium Compounds; D010710:Phosphates; D002129:Calcium Oxalate; D000069877:Struvite