Evaluation of GFR in horses of different age

The aim of the study was to evaluate GFR in horses of different age to verify differences between them. This study was approved by the ethical committee of the University (Pisa) and included 25 horses divided in group A: 8 foals (aged 10–30 days, median 18 days); group B: 7 young horses (aged 1–14 years, median 7 year); group C: 6 old horses (aged ≥14 years, median 23 years). GFR was evaluated using iohexol as marker and HPLC-UV method. A complete blook work and urinalysis were also performed. GFR results were expressed as mean and standard deviation. Komolgorov-Smirnov was applied to verify data distribution and t-test for unpaired data was applied. Statistical significance was set at P < 0.01. GFR values were 2.8 0.7 ml/min/kg, 2.5 0.3 ml/min/Kg, 2.2 0.1 ml/min/Kg in groups A, B and C, respectively. Statistical analysis showed differences between groups. Results on GFR obtained in the present study are comparable to literature for horses, while our results are slightly higher if compared to other authors for foals. This might be related to different age of foals included in the studies. GFR resulted statistically higher in foals respect to adult horses (both young and old ones) and this result might be related to the higher fluid intake in foals than in adult horses. The GFR in the older populations resulted statistically lower than young horses, thus GFR might decrease with age in horses as already reported in men and small dogs.