Diagnostic performance of blood analytes for the diagnosis of renal disease in black-footed ferrets (mustela nigripes) at the phoenix zoo (2001-2020).

Renal disease is an important cause of morbidity and mortality in managed black-footed ferrets (BFF; Mustela nigripes).4,6,12 The objectives of this study were to establish reference intervals for blood analytes of clinically normal BFF (1-2 yr old), summarize the frequency of various renal histopathologic findings in a managed population of BFF, assess the diagnostic performance of blood analytes and urine specific gravity (USG) for the diagnosis of renal disease, and assess if comorbidities or age affects the performance of these analytes in diagnosing renal disease. Reference intervals were established using a cohort (n = 35) of clinically normal, young adult BFF. Postmortem records for all BFF at the Phoenix Zoo between 2001 and 2020 were reviewed, and those with available blood analyte data within 2 wk of death were included (n = 89). Ferrets were placed into one of three groups, based on the organ location of histopathologic abnormalities following necropsy: renal disease as the primary change; those with renal disease and at least one other affected major organ system; or absence of abnormalities in the kidneys. In ferrets with substantial renal changes, the primary diagnosis was amyloidosis (29 of 39; 74.4%). Creatinine, blood urea nitrogen, phosphorus (P), calcium (Ca), Ca:P ratio, USG, globulins, and cholesterol were the best-performing analytes for the diagnosis of renal disease, with an area under the curve of at least 0.90 (95% CI $ 0.80, 1.00). Serum renal markers were within reference intervals in BFF that died without histologic evidence of renal disease. Several blood analytes were significantly affected by age in animals that died of renal disease. This study provides reference intervals for blood analytes in young adult clinically normal BFF and illustrates the clinical utility for the diagnosis of renal disease in this species, particularly creatinine, USG, and P.