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.