Associations between exercise-induced pulmonary haemorrhage, right ventricular dimensions and atrioventricular valve regurgitation in conditioned national hunt racehorses.

The research article is an investigation into a possible relationship between exercise-induced lung bleeding (EIPH), heart valve leakage, and right ventricle dimensions in racehorses.

Research Goal and Methodology

• The study aimed to investigate whether there’s a link between the conditions of EIPH, right ventricular dimensions, and the leakage (regurgitation) of the heart valves known as tricuspid (TR) and mitral valves (MR) in race-fit Thoroughbreds.
• This research hypothesis is based on the theory that horses experiencing repeated episodes of EIPH may develop unusual heart conditions due to increased pressure in the blood vessels of the lungs and cardiac output during training, leading to increased stress on the right ventricle (RV).
• To test the hypothesis, the study involved a thorough analysis of 121 race-fit National Hunt Thoroughbreds using echocardiographic and auscultation studies.
• The researchers performed cardiac auscultation and echocardiography, then acquired a guided M-mode image of the RV just below the tricuspid valve. They used Color flow Doppler (CFD) to examine the tricuspid valve, right atrium and mitral valve, grading the severity of TR and MR.
• Information regarding EIPH was gathered retrospectively for each horse by their primary veterinary surgeon from existing medical records. The data obtained were then analyzed using a standard logistic regression analysis approach.

Research Findings

• Based on the data obtained and analyzed, the research found that EIPH was significantly associated with both the systolic and diastolic dimensions of the RV, without any significant connection or sensitivity to the age or weight of the horse.
• However, the research didn’t find a significant association between EIPH and TR or MR as determined by both auscultation and CFD.
• While the EIPH classification method limited the study, the analysis found no correlation between EIPH and the age, weight, or TR or MR conditions of the examined Thoroughbred horses.
• Interestingly, it was observed that Thoroughbred horses visibly affected by EIPH had larger RV dimensions, which suggests that the conditions leading to EIPH may directly or indirectly affect how the right ventricle adapts in athletic horses.