ALTERATIONS IN BLOOD-VISCOSITY IN HORSES COMPETING IN CROSS-COUNTRY JUMPING

Packed cell volume and plasma total protein (TP), serum albumin (Alb) and globulin (Glb), and plasma ionized calcium (PCa) concentrations, b lood viscosity (BV), and plasma viscosity (PV) were measured in 42 hor ses at rest and after the cross country jumping phase of a horse trial competition The BV and PV were determined at 6 shear rates (230, 115, 46, 23, 11.5, 5.75 s(-1)), using a digital rotational cone and plate microviscometer. A paired t-test was used to determine differences bet ween PCV, TP, Alb, Glb and PCa values at rest and after exercise. The PCV, TP, Alb, and Glb values increased (P < 0.05) in horses after exer cise. The PCa concentration decreased (P < 0.05) in horses after exerc ise. Mean sv and PV in the 42 horses at rest and after exercise were f itted to an asymptotic function. Significant (P < 0.05) correlation at all shear rates was seen between BV at rest and PCV, TP, Alb, Glb, an d PCa values at rest; and between sv after exercise and PCV, TP, Alb, Glb, and PCa values after exercise. Significant correlation was not se en between PV at rest and TP, Alb, Glb, and PCa at rest, or between PV after exercise and TP, Alb, Glb, and PCa concentrations after exercis e at any shear rate.