EVALUATION OF THE MORPHOLOGIC CHARACTERISTICS AND PREVALENCE OF CANINE UROCYSTOLITHS FROM A REGIONAL UROLITH CENTER

Objective-To determine whether morphology of single-mineral urocystoli ths and age, sex, or breed data could be applied to facilitate radiogr aphic and clinical urocystolith mineral type prediction, respectively, in dogs. Sample Population-Database of 2,041 dogs with pure mineral c omposition urocystoliths. Procedure-All uroliths were characterized ac cording to geologic descriptive terminology and by breed, sex, and age of dog at time of sample submission. Summary statistics were used to compare features with specific mineral types. Observed trends were ana lyzed for statistical relevance between observed and expected frequenc ies for age, sex, color, size, shape, and surface, using the null hypo thesis that differences by urocystolith mineral type did not exist. On the basis of expected breed occurrence derived by equations, the null hypothesis that urocystolith occurrence paralleled canine breed popul arity was tested. Results-Urocystoliths > 10 mm in any dimension were > 92% likely to be magnesium ammonium phosphate hexahydrate (MAP). Smo oth, blunt-edged or faceted, and pyramidal urocystoliths were usually MAP. Jackstone shapes were almost always silica. Botryoidal (grape-lik e clusters) urocystoliths were likely to be oxalates. Breeds with high relative likelihood of urocystoliths included: English Bulldog, Pekin gese, Pug, Welsh Corgi, and West Highland White Terrier. Breeds with l ow relative likelihood of urocystolith production included: German She pherd Dog, Shar-Pei, and German Shorthaired Pointer. About 94% of uroc ystoliths produced in females or spayed females were MAP, whereas male s and neutered males produced a greater assortment. Conclusions and Cl inical Relevance-For pure mineral composition urocystoliths, trends in mineral type among breeds and between sexes can be exploited clinical ly in the diagnosis and management of urolith-related disease. Size an d shape, used in conjunction with age, breed, and sex, can facilitate pure urocystolith mineral type prediction.