Objective: to test the hypothesis that breed, sex and age of cats, and anatomic location of uroliths are risk factors for calcium oxalate and magnesium ammonium phosphate urolithiasis.
Design: Retrospective case-control study.
Sample population: Records of 3,498 feline urolith accessions submitted between September 1982 and September 1992.
Procedure: Mineral composition of feline uroliths was quantitatively analyzed. Odds ratios and 95% confidence intervals were calculated for breed, sex, age, and urolith location as risk factors for calcium oxalate and magnesium ammonium phosphate urolith formation. The population at risk was defined as all cats for which that type of urolith had been submitted. The control population was all cats for which uroliths had been submitted, excluding cats with the type of urolith being evaluated.
Results: Burmese, Persian, and Himalayan breeds were at higher risk for developing calcium oxalate uroliths, but at reduced risk for developing magnesium ammonium phosphate uroliths. Compared with females, neutered male cats had a higher risk for developing calcium oxalate uroliths, but a reduced risk for developing magnesium ammonium phosphate uroliths. The risk for calcium oxalate urolith formation increased with age. One- to 2-year-old female cats had the highest risk for magnesium ammonium phosphate uroliths. Uroliths removed from the kidneys were more likely to be composed of calcium oxalate than of magnesium ammonium phosphate.
Clinical implications: Breed, sex, and age of cats, and anatomic location of uroliths should be considered when evaluating risk of calcium oxalate and magnesium ammonium phosphate urolithiasis in urolith-forming cats.