Epidemiological evaluation of cystine urolithiasis in domestic ferrets (Mustela putorius furo): 70 cases (1992–2009)

Abstract Objective—To determine the prevalence of cystine uroliths in domestic ferrets with urolithiasis and determine whether age, breed, sex, reproductive status, anatomic location, and season are risk factors associated with cystine urolith formation. Design—Retrospective cross-sectional case-control study. Sample—Records of 435 ferrets (Mustela putorius furo) with uroliths submitted for analyses between 1992 and 2009, of which 70 were cystine uroliths. Procedures—Specific descriptive information was obtained about each ferret to determine whether specific risk factors were associated with the development of cystine uroliths. Results—Cystine uroliths comprised 70 of the 435 (16%) uroliths. Cystine uroliths were more common in male (n = 54) than in female (16) ferrets. All cystine uroliths were retrieved from the lower portion of the urinary tract (bladder and urethra [n = 67]) or were voided (3); none of the uroliths were retrieved from the upper portion of the urinary tract (kidney and ureters). Conclusions and Clinical Relevance—Awareness of the prevalence of cystine uroliths along with knowledge of etiologic, demographic, and environmental risk and protective factors for urolithiasis may facilitate development of surveillance strategies that result in earlier detection of cystinuria. Genetic factors associated with this disease have not yet been reported in ferrets, but a familial pattern of inheritance determined to be a major underlying factor in cystine urolithiasis in dogs and humans suggests that this may be a factor in ferrets and that the parent stock of ferrets in the present study may have been inbred.