Epizootiologic evaluation and quantitative analysis of urinary calculi from 150 cats.

One hundred fifty specimens of urinary calculi from 150 cats were analyzed by at least 1 of 4 quantitative methods. Struvite (magnesium ammonium phosphate) was the predominant mineral substance encountered, with 104 (69%) of the calculi being composed entirely of struvite and 23 (15%) being composed partially of struvite. Most (93%) of the calculi were located in the urinary bladder. Growth of bacteria was observed in samples from calculi or urine from 30 (41%) of 74 cats. Coagulase-positive staphylococci were isolated from the urine or calculi from 17 cats (45% of bacteria isolated). Ten other bacterial species were isolated. Median and mean ages of the cats were 5.0 and 5.1 years, respectively. Domestic short-hair and domestic longhair breeds predominated. Fifty-seven percent of the calculi came from females, 43% from males. The distribution by gender did not differ significantly (P greater than 0.2) among the 3 groups (domestic shorthair, domestic longhair, and other). However, the distribution of struvite calculi differed significantly (chi 2 = 15.5, P less than 0.001) by age and gender; among cats less than or equal to 2 years of age, males predominated 2:1 over females, and among cats greater than 2 years of age, females predominated by nearly 3:1 over males. When compared with the general population, females greater than 2 years old were significantly (chi 2 = 15.4, P less than 0.001) overrepresented.