Relationships between the erythrocyte sedimentation rate, plasma proteins and viscosity, and leucocyte counts in thoroughbred racehorses.

This research looks at how plasma proteins influence the aggregation of red blood cells in young thoroughbred racehorses. Specifically, it focuses on how factors such as haematocrit, fibrinogen, plasma viscosity, and serum total globulins are associated with this aggregation.

Objective and Methodology

• The study aims to understand the relationship between erythrocyte sedimentation rate (ESR), an indicator of inflammation in the body, and plasma proteins like fibrinogen, and serum total globulins in thoroughbred racehorses.
• The researchers used a 60-minute ESR test with and without haematocrit standardization. Haematocrit refers to the ratio of the volume of red cells to the total volume of blood.

Findings and Analysis

• The ESR was found to be inversely correlated with the haematocrit – as the haematocrit increased, the ESR decreased, and vice-versa.
• However, they found a direct correlation between ESR and fibrinogen, plasma viscosity, and serum total globulins – an increase in these plasma proteins related to an increase in ESR.
• When the ESR values were standardized to a common haematocrit, the correlation coefficients for these plasma protein factors were even higher.
• The study also found a strong direct relationship between albumin levels and haematocrit, explaining the inverse correlation between albumin and ESR.
• When the ESR was standardized with haematocrit, no significant correlation was found with albumin levels.
• The total white blood cell count and the absolute neutrophil count – an indicator of immune response – did not show any correlation with either ESR or haematocrit standardized ESR.

Conclusion and Implications

• The key finding was a high correlation (r=0.75) between fibrinogen levels and haematocrit standardised ESR.
• This indicates that differences in levels of fibrinogen, a protein that aids in blood clotting and increases during inflammation, can influence the degree of red cell aggregation (clumping together of red blood cells) and rouleaux formation (stacking of red blood cells, resembling a roll of coins) in horses.
• This insight can be valuable in diagnosing and managing inflammatory conditions in racehorses, where optimal physical health is crucial.