An echocardiographic and auscultation study of right heart responses to training in young national hunt thoroughbred horses.

This research investigates the impact of race training on the heart function of Thoroughbred horses, finding that athletic training affects the severity and prevalence of heart valve incompetence and that heart dimensions increase with age and training.

Objective & Methodology

• The study was intended to explore how commercial racing training affects the function of the right ventricle and tricuspid valve in untrained National Hunt Thoroughbreds.
• A group of 90 Thoroughbred horses aged 2-7 years was examined between 1998 and 2003, with some horses examined more than once.
• The examinations included M-mode echocardiography of the right ventricle, colour flow Doppler (CFD) evaluation of the tricuspid valve and right atrium, and cardiac auscultation.
• Examinations were categorized based on training stages: before race training, after 8-12 weeks of cantering exercise, and at full race fitness.
• Tricuspid valve issues were graded using a scale of 1-6 for reported murmurs and 1-9 for CFD echocardiography signals.
• Right ventricular internal diameter (RVID) was also measured during diastole and systole (RVIDd and RVIDs).
• General linear mixed models were used to study associations between RVID and tricuspid valve measurements and covariates such as weight, age, heart rate, yard, and stage of training.

Findings

• The study found that with each year increase in age, RVIDd and RVIDs increased by 0.08 and 0.1 cm respectively. Similarly, they observed a growth of 0.3 and 0.4 cm respectively between pre-training and race fitness.
• Tricuspid regurgitation score on colour flow Doppler increased by 0.6 with each year of age and by 1.8 between pretraining and race fitness.
• The research found no significant associations between any outcomes and the horses’ weight, heart rate, and training yard.
• The high level of correlation between age and training made multivariable models indistinguishable.

Conclusions

• The study concludes that athletic training has independent effects on the severity and prevalence of tricuspid valve incompetence in horses.
• This result suggests that the impact of training should be considered when performing examinations on horses.
• The dimensions of the horse’s right ventricle (RV) were found to increase with age and training in a way that’s similar to the left ventricle (LV) .