Abstract
BackgroundThe heart’s physiological adaptation to aerobic training leads to an increase in heart chamber size, and is referred to as the Athlete's heart. However, heart dimensions are also related to body weight (BWT), body size, growth and (in some species) breed. There are few published data on the relationships between heart dimensions and growth or aerobic training in Arabian and Arabian-related endurance horses. Therefore the objective of the present study was to describe the influence of body dimensions (body length (BL), thoracic circumference (TC), withers height (WH)), BWT, age, gender, breed (purebred Arabians, part-bred Arabians, Anglo-Arabians, and Others) and the initiation of endurance training on echocardiographic measurements in competition-fit endurance horses aged 4 to 6 years.ResultsMost left atrial (LA) and left ventricular (LV) dimensions increased with age, whereas LA and LV functional indices did not. Although there was no gender difference for LV dimensions, females had larger LA dimensions. In terms of breed, Anglo-Arabians had the largest LV dimensions. Regression models indicated that the included explanatory factors had a weak influence on heart dimensions. Age, body dimensions, breed and gender showed the most consistent influence on LA dimensions, whereas BWT, breed and kilometres covered in competition showed the most consistent influence on LV dimensions.ConclusionThe increase in echocardiographic dimensions with age indicates on-going growth in our population of 4 to 6 year-old horses. We also observed small changes associated with the initiation of endurance training. Morphometric dimensions had a greater influence on LA dimensions, whereas LV dimensions were also influenced (albeit weakly) by parameters associated with exercise intensity. These results may therefore reflect early adaptations linked to the initiation of endurance training.Electronic supplementary materialThe online version of this article (doi:10.1186/s12917-016-0846-x) contains supplementary material, which is available to authorized users.
Highlights
The heart’s physiological adaptation to aerobic training leads to an increase in heart chamber size, and is referred to as the Athlete's heart
Given that the field conditions limited the available time per horse, the number of missing data varied from one measurement to another
The numbers of available data per measurement are given in Additional files 1, 2, 3 and 4
Summary
The heart’s physiological adaptation to aerobic training leads to an increase in heart chamber size, and is referred to as the Athlete's heart. Heart dimensions are related to body weight (BWT), body size, growth and (in some species) breed. There are few published data on the relationships between heart dimensions and growth or aerobic training in Arabian and Arabian-related endurance horses. The objective of the present study was to describe the influence of body dimensions (body length (BL), thoracic circumference (TC), withers height (WH)), BWT, age, gender, breed (purebred Arabians, part-bred Arabians, Anglo-Arabians, and Others) and the initiation of endurance training on echocardiographic measurements in competition-fit endurance horses aged 4 to 6 years. The primary objective of the present study was to describe the development of the heart in young Arabian-type horses aged between four and six years, an age at which endurance training is usually initiated. The second objective was to assess a possible association between external factors and the echocardiographic dimensions of the heart’s chambers and great vessels in these horses
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