Effect of longeing and glucosamine supplementation on serum markers of bone and joint metabolism in yearling quarter horses

The effect of longeing and glucosamine supplementation on known biological markers of joint disease was studied in yearling quarter horses. Twenty-one yearling quarter horses were randomly assigned to one of 4 treatments: 1) longeing (longeing 20 min daily) supplement control (LN); 2) longeing/gluco samine (LG); 3) walking (mechanical walker for 120 min daily (WN)); and 4) walking/glucosamine (WG), Oral glucosamine was administered at 5.5 g b.i.d. weeks 1-4, 3.5 g b.i.d. during weeks 5-6, and 2.0 g b.i.d. during weeks 7- 8, Serum was obtained weekly for 8 wk and analyzed for keratan sulfate and osteocalcin concentrations. Walked horses receiving glucosamine showed slig ht elevation in serum keratan sulfate compared to controls (P = 0.04), Gluc osamine or longeing exercise had no significant effect (P greater than or e qual to 0.08) on serum osteocalcin concentrations. Under these conditions, longeing and/or glucosamine supplementation did not significantly alter ser um concentrations of keratan sulfate or osteocalcin.