Feline uroliths: Analysis of frequency and epidemiology in Germany (2016-2020)

Abstract

This study was aimed to assess the distribution and frequency of uroliths in cats as well as to evaluate gender-, age-, and breed-specific differences. 3629 uroliths from cats in Germany were analyzed by infrared-spectroscopy during the period 2016-2020. The majority (3300) of the uroliths originated from purebred cats of 22 breeds. Uroliths were prevalent in the order of male neutered (45.3 %), female spayed (35.3 %), male intact (7.4 %), and female intact cats (6.3 %). Median age of the cats with uroliths was 7 years, although it varied slightly depending on types of the urolith. The most frequent uroliths were calcium oxalate (59.5 %), followed by struvite (33.7 %), ammonium urate (2 %), calcium phosphate (1.7 %), cystine (0.7 %) and xanthine (0.4 %). Males (59.4 %) and females (59.2 %) showed nearly identical prevalence of calcium oxalates, whereas it significantly diverged in castrated (60.2 %) versus intact animals (54.4 %; p = 0.01). With regard to struvites, male cats (32.6 %) were less prone than females (35.4 %; p = 0.08) while intact cats (38.2 %) significantly outnumbered the castrated cohorts (33.1 %; p = 0.02). The prevalence for calcium oxalate uroliths increased by 6.6 % during the study period, contrasting a decrease of 5.5 % for struvites. Some breeds (> 10 individuals) showed significantly higher propensities than others for urolith formation. Calcium oxalates were significantly more frequent in British shorthair cats (85.2 %), Ragdoll (75 %), Scottish fold (74.1 %) and Persians (72.4 %). Struvites were prevailing in Norwegian forest cats (48.5 %), British longhair (41.7 %), European shorthair (41.7 %) and Siberian forest cats (36.8 %). Siamese cats had the significantly highest percentage of cystine uroliths (16 %). The occurrence of urine calculi in cats from Germany was found to be most frequent for calcium oxalate and struvite types. We also found breed-, age-, gender- specific differences in addition to variations depending on the neutering status of the animals.