Measurement of Selected Renal Biochemical Parameters in Healthy Adult Donkeys Considering the Influence of Gender, Age and Blood Freezing

SIMPLE SUMMARY: In animal medicine, laboratory test profiles containing selected blood or urine parameters are used to diagnose diseases of a given organ. The normal values of the serum and urine biochemical parameters are well-known in horses, but they have not been studied well in donkeys. This means that their results are often compared with horses’ reference values. The interest in donkeys continues to grow, as well as increasing attention being paid to kidney damage in animals. The objective of the study was to determine the values of the selected serum and urine parameters to assess the renal function in healthy donkeys. The effects of age, sex and freezing of the material were then assessed. Sixty-five healthy adult donkeys participated in the study. The results showed different reference values for the kidney parameters such as urea, total protein, albumin, urine protein/creatinine ratio and fractional electrolyte excretion in donkeys compared to those reported for horses. The donkeys’ gender had an effect on the creatinine and urea, while age had an effect on the albumin, total protein and electrolytes. Freezing of the material also influenced most of the parameters. To the authors’ knowledge, this is the first study to analyze the selected renal biomarkers in donkeys. ABSTRACT: The reference values of the serum and urine biochemical parameters have not been well-studied in donkeys. This study aimed to assess the normal values of the selected renal biomarkers, such as: serum creatinine, blood urea nitrogen (BUN), albumin, total protein (TP), electrolytes and symmetric dimethylarginine (SDMA), urine protein concentration (UPC), urine protein/creatinine ratio (UPCR), the urine gamma-glutamyl transferase (GGTP)-to-creatinine ratio, serum creatinine-to-urine creatinine ratio (sCr/uCr), serum BUN-to-serum creatinine ratio (sBUN/sCr) and UPC-to-TP ratio, as well as the fractional electrolyte excretion of sodium (FENa) and potassium (FEK) in donkeys. The effects of age, gender and deep freezing of the serum material were investigated. Sixty-five healthy adult donkeys were involved in this study. The results showed higher BUN and TP values and lower albumin, UPCR, FENa and FEK levels in donkeys when compared to the reference values in horses. A significant gender relationship for creatinine and BUN was found. Age influenced the values of albumin, TP, potassium and chlorine. Potassium, sodium and SDMA did not show significant concentration changes after freezing. The study results demonstrated that horse reference range values for some parameters cannot be applied to donkey samples. Only a few of the serum parameters were not affected by freezing, and this should be taken into account when storing biological materials.