UROLITHIASIS in FOXES: ASSESSMENT of 65 UROLITH SUBMISSIONS to the MINNESOTA UROLITH CENTER from 1981 to 2021

This article summarizes urinary stone submissions from foxes in human care to the Minnesota Urolith Center over 40 years. A previous report documented the analysis of uroliths from foxes that were submitted between 1981 and 2007.13 New data compiled from 2008 to 2021 included an additional 38 stones submitted from foxes, totaling 65 fox urolith submissions from 1981 to 2021. Struvite and cystine uroliths were most common, with the remainder comprised of calcium phosphate, calcium oxalate, compound, mixed, or miscellaneous material. Most stones were submitted from male foxes. Seventy-two percent of the stones were urocystoliths, and from 2010 to 2021, most stones were diagnosed antemortem and removed surgically. More than half of the stones were submitted from red foxes (Vulpes vulpes) and fennec foxes (Vulpes zerda). Urolithiasis in foxes may be an underrecognized condition, and data from this study suggest that clinicians should consider routine urinalysis and diagnostic imaging as part of the preventive medicine program for fox species, especially red foxes and fennec foxes.