Association between uropathogens and the occurrence of magnesium ammonium phosphate and calcium oxalate in cats with urolithiasis: a retrospective study (2016–2021)

ObjectivesThe incidence of calcium oxalate (CaOx) urolithiasis in cats is rising globally, while magnesium ammonium phosphate (MAP) uroliths remain prevalent. MAP uroliths are commonly associated with urease bacterial infection in dogs. Urinary tract infections (UTIs) could increase the risk of urolithiasis, but there have only been limited studies to date in cats in developing countries. This study evaluates the association between UTI, sex, age and the occurrence of MAP uroliths compared with CaOx uroliths in cats treated for urolithiasis at Kasetsart University Veterinary Teaching Hospital, Thailand.MethodsA retrospective study was conducted of medical records from cats undergoing surgery for urolithiasis at Kasetsart University Veterinary Teaching Hospital, Thailand between 2016 and 2021. Data retrieval included mineral type, age, sex, breed and culture results. Uroliths were analysed via Fourier-transform infrared spectroscopy. Odds ratios (ORs) and 95% confidence intervals (CIs) assessed risk factors for MAP urolith formation.ResultsData from 264 cats (168 males, median age 5 years; 95 females, median age 5.1 years; one unidentified) were included. Calcium oxalate (CaOx) was the most common urolith (170/264, 64.4%), followed by MAP urolithiasis (80/264, 30.3%). A total of 176 urine samples were cultured, of which 36/58 MAP cases, 32/107 CaOx cases and 5/11 other urolith cases tested positive. The most common bacteria were <i>Staphylococcus</i> species (21/73, 28.8%), <i>Escherichia coli</i> (16/73, 21.9%) and <i>Enterococcus</i> species (9/73, 12.3%). Multiple logistic regression indicated strong urease-producing bacteria increased MAP risk by 11.93 times (OR 11.93, 95% CI 4.28-33.23) and other bacteria (<i>Enterococcus</i> species, <i>Pasteurella</i> species, <i>Acinetobacter</i> species) increased risk by 3.84 times (OR 3.84, 95% CI 1.32-11.12). Age and sex had no significant effect.Conclusions and relevanceThe findings of this study unveiled an association between strong urease-producing bacteria and MAP in cats with urolithiasis.