Prevalence of reduced fibrinogen binding to platelets in a population of Thoroughbreds.

This research studies the presence and extent of reduced fibrinogen binding in a population of Thoroughbred horses, with the conclusion that it is indicative of a hereditary bleeding disorder. This disorder is distinguished from another bleeding disorder called Glanzmann thrombasthenia, and seems to be more prevalent in this specific study group than in more varied groups.

Research Methods

• This study involved 444 Thoroughbred horses, aged between 1 to 27 years, and including 316 females, 72 geldings, and 56 sexually intact males.
• The horses’ blood was collected in tubes containing acid citrate dextrose adenine, which helps to prevent the blood from clotting.
• The researchers then examined the ability of washed platelets in the collected blood to bind to fibrinogen using flow cytometry, a technology that can analyze physical and chemical characteristics of particles in a fluid as it passes through a laser.

Research Findings

• Data about fibrinogen binding to the horses’ activated platelets was normally distributed, showing nearly the same amounts of variation irrespective of the horse’s sex.
• For three of the horses, fibrinogen binding to the platelets was reduced from 67.6% to 83.4%, compared to normal platelets. This suggests the platelets were less able to aggregate (group together), which is usually triggered by thrombin.
• This characteristic of the platelets in the affected horses reveals signs similar to a known inheritable bleeding disorder, particularly as the reduction in fibrinogen binding ties to extended bleeding times in template bleeding assays (tests to measure how long it takes for bleeding to stop).

Conclusions and Significance

• This measured bleeding disorder in the horses is distinct from a condition known as Glanzmann thrombasthenia, which also impairs platelets’ ability to bind fibrinogen, albeit due to a deficiency in alphallb-beta3 integrin on their surface, rather than reduced fibrinogen binding capacity.
• The prevalence of this condition within the studied population (0.7% or 3 of the studied horses) signifies a higher than expected frequency compared to the prevalence of such bleeding disorders in more genetically diverse groups.