Biochemical markers of bone metabolism in draught and warmblood horses

Concentrations of the cross-linked carboxyterminal telopeptide of type I co llagen (ICTP) and osteocalcin (OC) have been determined in the serum of one hundred clinically healthy adult Draught or Warmblood horses. The correlat ion between these two markers has been evaluated and the influence of gende r, age and type of horse described. No significant variations were observed between animals of different sex, but a significant inverse correlation (P <0.0001) with age was observed for both measured parameters. After correcti on for age, serum levels of OC were found to be lower in Draught [adjusted least square mean (LSM)=6.612 mu g.L-1] than in Warmblood horses (adjusted LSM=8.596 mu g.L-1), whereas levels of ICTP were higher in Draughts (adjust ed LSM=8.035 mu g.L-1) than in Warmbloods (adjusted LSM=G.643 mu g.L-1. A s ignificant correlation (P<0.0001) was observed between OC and ICTP. This co rrelation was stronger if the type of horse was taken into account in the s tatistical model. The ratio OC:ICTF was independent of gender and age. A hi gher OC:ICTP ratio in Warmbloods compared to the Draught horses might refle ct a higher bone remodelling level of horses submitted to regular daily wor k. It was concluded that ICTP and OC are influenced by the type of horse, a nd probably reflect a physiological difference in bone remodelling between these animals.