Clinical utility of estimation of glomerular filtration rate in dogs

Background Glomerular filtration rate (GFR) estimation is the gold standard for assessment of renal function, although the clinical utility of this test is unclear. Objectives To describe the clinical utility of GFR estimation in dogs. Animals Medical records of 132 dogs that had serum iohexol clearance measured between 2012 and 2017. Methods Iohexol clearance and clinical records were reviewed and submitting practices contacted to obtain outcome data. Dogs were classified into 4 groups based on the reason for performing GFR estimation: A1 (screening for pre-azotemic chronic kidney disease [CKD], n = 105), A2 (confirmation of azotemic CKD, n = 3), B (screening for pre-azotemic acute kidney injury, n = 19), and C (miscellaneous causes, n = 5). Descriptive review of the clinical utility of GFR estimation is provided. Results For dogs in Group A1, renal disease was diagnosed in 9/9 dogs with a GFR >= 40% decreased below the mean GFR of their body weight category, in 5/6 dogs with a >= 30% but <40% reduction in GFR and in 7/9 dogs with a >= 20% but <30% reduction in GFR. Conclusions and Clinical Importance Glomerular filtration rate estimation is useful for the diagnosis of CKD before the onset of azotemia.