Heart murmurs and valvular regurgitation in thoroughbred racehorses: epidemiology and associations with athletic performance.

The research investigates the link between heart murmurs and valve regurgitation in performance racehorses, their prevalence in different types of racing, and whether these conditions affect the horses’ racing performance.

Objective

The main objective of the study was to determine if heart murmurs and valvular regurgitation have a negative impact on race performance of Thoroughbred racehorses. These two conditions are common in performance horses, but their effect on athletic performance has not been firmly established.

Methods

• The study was based on 526 Thoroughbred racehorses involved in flat or jump racing, covering race distances from 1,000 to 6,400 meters.
• The research team carried out cardiac auscultation and color flow Doppler (CFD) echocardiography on 777 occasions to detect the presence and severity of heart murmurs and valvular regurgitation.
• The researchers than compared these findings with objective measures of race performance using a standard regression approach.

Results

• The study found significant variance in the prevalence of heart murmurs and valvular regurgitation depending on the type of race, with prevalences typically increasing from younger to older horses.
• However, the study did not establish any consistent associations between the grade of heart murmurs or regurgitation and the racing performance of the horses.
• This lack of association was consistent even when considering only severe cases of valvular regurgitation and murmurs.

Conclusions

• The research concluded that there are significant differences in the prevalence and severity of heart murmurs and valvular regurgitations among racehorses participating in different disciplines.
• However, the findings also indicate that neither of these conditions have a negative impact on the quality of race performance when measured using the Timeform rating, a UK index of racehorse quality.