Altered systolic left ventricular function in horses completing a long distance endurance race.
BACKGROUND
It is unknown whether or not exercise-induced cardiac fatigue (EICF), as demonstrated in human athletes performing long duration exercise, occurs in endurance horses.


OBJECTIVE
To examine the effects of a long distance endurance race on left ventricular systolic function in horses.


METHODS
Echocardiography was performed before, and after, a 2 or 3 star international endurance race (106-132 km) in 11 horses. Systolic (s) and diastolic (d) interventricular and left ventricular free wall thickness (IVS and LVFW, respectively), left ventricular, left atrial and aortic internal diameter (LVID, LA and Ao, respectively), fractional shortening (FS) and ejection fraction (EF) were measured by echocardiography. Heart rate (HR), peak flow velocity (Vmax), flow velocity integral (FVI), ejection time (ET), pre-ejection period (PEP), velocity of circumferential fibre shortening (Vcf), stroke volume (SV) and cardiac output (CO) were measured from aortic Doppler wave recordings.


RESULTS
After the race, LVIDd, Ao, LA, EF, FS, FVI, SV, ET and ET indexed for HR were significantly lower and IVSd, LVFWd, HR, PEP, PEP/ET and Vcf significantly higher as compared with prerace values. Pre- to post exercise changes in those parameters were not significantly correlated with changes in HR or in LVIDd.


CONCLUSIONS
Results suggest that EICF, with a decrease in left ventricular systolic function, could occur post exercise in horses performing long duration endurance races. However, a multanecus effect of altered preload and heart rate on the studied variables cannot be discounted.
Equine Clinic, Clinical Department of Companion Animals and Equids, Faculty of Veterinary Medicine, University of Liege, Sart Tilman, Liege, Belgium. helene.amory@ulg.ac.be
H
H
Amory
D-M
DM
Votion
A
A
Fraipont
A G
AG
Goachet
C
C
Robert
F
F
Farnir
E
E
Van Erck
D000818:Animals; D005260:Female; D006736:Horses / Q000502:physiology*; D008297:Male; D010805:Physical Conditioning, Animal / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology*; D013318:Stroke Volume / Q000502:physiology; D013599:Systole / Q000502:physiology*; D016277:Ventricular Function, Left / Q000502:physiology*