Evaluation of Urinary Variables as Diagnostic Indicators of Acute Kidney Injury in Egyptian Draft Horses Treated With Phenylbutazone Therapy

The present study was undertaken to evaluate the diagnostic significance of various urinary variables to detect acute kidney injury (AKI) in Egyptian draft horses treated with phenylbutazone (PBZ) therapy. Medical records of 52 draft horses, with a history of musculoskeletal painful conditions and treated frequently with various daily doses of injectable PBZ, were reviewed. Of those 52 horses, 38 were enrolled in this study. AKI was tentatively diagnosed based on thorough history and clinical findings and in conjunction with multiple biochemical screening tests. Accordingly, diseased horses were categorized into two main groups; the first group included 14 horses with prerenal azotemia, whereas the second group included 24 horses with renal azotemia. Biochemically, urinary malondialdehyde, urinary gamma-glutamyl transferase/creatinine (Cr) ratio, urinary protein/Cr ratio, urinary glucose, urinary sodium, fractional excretion of sodium, and renal failure index were significantly higher (P < .05) in horses of group 2 than those of group 1. However, values of urinary Cr, urine/plasma Cr ratio, urinary urea, and urine/plasma urea ratio were significantly decreased (P < .05) in horses of group 2. Analysis of receiver operating characteristic curve showed high sensitivity and specificity of most tested urinary variables as well as their derived indices for detection of AKI in diseased horses. Our findings suggest that the examined urinary variables as well as their ratios are helpful in documenting AKI associated with PBZ nephrotoxicity in Egyptian draft horses; however, their interpretation should be done in the light of the specific clinical setting and in conjunction with a thorough clinical and physical examination.