Use of color Doppler echocardiography to assess the development of valvular regurgitation in Standardbred trotters.

This research study conducted longitudinal observations on Standardbred trotters, investigating the rate and evolution of valvular regurgitation—a condition where the heart’s valves do not properly close, causing blood to leak backwards—and its impact on the horses’ racing performance. The study found a higher frequency of regurgitation in horses regularly raced and identified characteristics such as being male and having a bigger left ventricular mass and internal diameter to be common in such horses. However, racing performance did not appear to be affected by this condition.

Research Methodology

In the study, the researchers employed various methods:

• The researchers selected a sample size of 103 Standardbred trotters for the study.
• They performed echocardiographic examinations four times at six-month intervals. Echocardiography is a diagnostic test that uses ultrasound waves to produce images of the heart. This allows doctors to monitor how well the heart and its valves are working.
• They employed two techniques to visualize the heart: Two-dimensional echocardiography and M-mode echocardiography. The former provides a real-time view of the heart that can show the heart’s structure and motion, while the latter obtains time-motion pictures of the heart’s structures.
• Color Doppler imaging was used to identify and assess the extent of the regurgitant (backwards-flowing) blood at each valve of the horse’s heart.

Findings of the Study

• The incidence of valvular regurgitation in all the cardiac valves rose substantially over the 18 months of the research. Despite the increase, all cases of regurgitation were classified as mild.
• The severity of the valvular regurgitation did not progress in any of the horses throughout the course of the study.
• The study found tricuspid regurgitation—the backflow of blood through the tricuspid valve—was more common in horses that raced regularly.
• In terms of demographics, male horses and those with larger left ventricular masses and internal diameters during diastole were more likely to be diagnosed with tricuspid regurgitation.
• However, researchers did not find any correlation between a horse’s racing performance and the presence of valvular regurgitation.

Conclusions of the Study

• Valvular regurgitation became more common as the horses aged from 2 to 3.5 years. However, the study could not determine whether this was due to maturity or the effect of training.
• While there was a high prevalence of mild valvular regurgitation at 3.5 years of age, it did not affect the racing performance of the horses in this age group.
• The potential impact of valvular regurgitation on future performance, or whether the condition will progress, remains unknown.