Serum folate levels in horses, with particular reference to the English thoroughbred

The assay of serum folate has been used to investigate the folate status of thoroughbreds in training to race, in-foal thoroughbred mares at stud and crossbred ponies kept permanently at grass. Throughbreds in training, with no obvious haematological or clinical abnormalities, had lower serum folate levels (mean 3.3, range 1.5 to 6.1 microgram per litre) compared with thoroughbred mares at stud (mean 10.6, range 6.4 to 15.8 microgram per litre) and crossbred ponies at grass (mean 10.9, range 7.4 to 16.6 microgram per litre. Intensive exercise, over a period of six months, significantly decreased serum folate levels (P less than 0.001) and significantly increased the levels of bilirubin (P less than 0.0001) and PCV (P less than 0.0002) in a group of 30 thoroughbred racehorses. Haptoglobin levels showed no significant changes.