Effects of racing and gender on viscoelastic properties of horse blood.

This research looked into how horse racing affects the elastic properties of a horse’s blood, taking into account gender differences. It found that racing increases factors such as erythrocyte counts, erythrocyte size variability, and plasma fibrinogen concentration, among others. Notably, gender differences were observed in the elastic yield stress (EYS) of blood following racing, with mares showing an increase but not geldings.

Background

• This research investigates the effects of horse racing on the viscoelastic properties of horse blood. The focus of the study is on hematocrit (hct) level increases in the blood, which raises blood viscosity – its resistance to flow. The researchers also studied these effects with respect to gender, focusing on mares and geldings.

Methodology

• The study involved taking blood samples from horses before and after racing. The races ranged in distance from 0.32 km up to 1.7 km.
• Using these samples, the researchers measured various properties of the horse blood, including erythrocyte (red blood cell) count, mean erythrocyte volume, heterogeneity of RBC (Red Blood Cell) size, plasma fibrinogen concentration, erythrocyte sedimentation rate, and elastic yield stress (EYS).

Findings

• Racing resulted in increased erythrocyte count and mean erythrocyte volume in both mares and geldings, regardless of the race’s length.
• There was also a notable increase in the heterogeneity of RBC size, plasma fibrinogen concentration, and erythrocyte sedimentation rate in both sexes after racing.
• The study found that the elastic yield stress (EYS) of the blood also increased after racing. When the results were standardized for a hematocrit level of 65%, mares showed an increase in EYS but not geldings.

Significance

• Elastic Yield Stress (EYS) is comparable to the force needed to get ketchup flowing out from a bottle. In the context of blood flow, an increase in EYS could potentially be harmful in vascular areas with pulsatile flow like the coronary circulation. This is because a higher EYS means that more force is required to get blood flowing, potentially straining the heart and vascular system.
• The study found significant gender differences in how racing affects the elastic properties of blood, with mares showing a notable increase in EYS compared to geldings.
• However, the researchers did not find that these gender differences could be explained by differences in fibrinogen response. They stated the need for further research to determine the mechanisms behind the observed gender differences in EYS response.