Effect of frusemide on bodyweight loss and recovery in racing Standardbreds.

This study was conducted to compare bodyweight (bwt) loss and recovery in Standardbred horses receiving frusemide compared to controls. Thirty Standardbred horses from 7 training stables that were racing at the Red Mile in Lexington, Kentucky, during the spring 2001 pari-mutuel meeting were studied. Fourteen horses (FRU) received frusemide (250 mg/horse i.v.) 4 h prior to racing, while 16 horses (NFRU) did not received frusemide. Horses were weighed on the morning of race day, prior to warm-up, after racing and the next day. Changes in bwt were calculated as percentage increase or decrease from initial bwt. Prior to warm-up, FRU horses had a mean bwt reduction of 1.30 +/- 0.63%, (P<0.01), compared to a 0.19 +/- 0.63% increase for the NFRU horses. FRU horses had a greater (P<0.03) postrace bwt loss (3.55 +/- 0.55%) than the NFRU horses (2.71 +/- 0.66%). On the morning after racing, bwt was still below initial values by 0.90 +/- 0.55 and 1.24 +/- 0.35% for the FRU and the NFRU horses, respectively. While frusemide administration increased the postrace weight loss in racing Standardbreds, it did not affect short-term bwt recovery. Further research is required into management strategies required to allow horses to replenish fluids and electrolytes safely following strenuous exercise.