Cystine and urate cystoliths in dogs are frequently visible on radiographs prior to surgical or nonsurgical removal.

Abstract

OBJECTIVE: To investigate the frequency at which cystine and urate cystoliths (stones) are visible on radiographs prior to surgical or nonsurgical retrieval. METHODS: Records of client-owned dogs (n = 331) were analyzed between January 2019 and December 2023 for cystoliths submitted for stone analysis after surgical removal or nonsurgical retrieval. Records were analyzed for cystolith type; when cystine or urate stones were identified, records were analyzed for signalment, procedure, presence of mineral opaque cystoliths on pre-procedural radiographs, urine pH and crystalluria, history of previous cystoliths, prior prescription diet attempt, recurrence, and genetic, congenital and acquired comorbidities. Descriptive statistics were generated after data collection. RESULTS: 31 of 331 (9%) were cystine stones, 49 of 331 (15%) were urate, and 1 of 331 (0.3%) was a mix of urate and cystine. When radiographs were taken prior to stone removal, 24 of 28 (85%) of urate, 24 of 26 (92%) of cystine, and 1 of 1 (100%) of urate/cystine were visible on radiographs. CONCLUSIONS: Cystine and urate stones are visible on survey radiography at a high frequency in dogs. CLINICAL RELEVANCE: While cystine and urate stones have been historically designated as radiolucent, they are frequently radiopaque on radiographs. Radiopacity is commonly used as one of the criterion to determine whether a dissolution or prevention diet is an appropriate management technique, particularly when determination of the stone type has yet to be performed. As a result, these findings may prompt clinicians to investigate other patient-specific factors before a specific dietary recommendation is made.