Relationships between body dimensions, body weight, age, gender, breed and echocardiographic dimensions in young endurance horses

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.

Evaluation of age‐dependent changes of myocardial velocity using pulsed wave and colour tissue Doppler imaging in adult warmblood horses

“…Several studies in healthy dogs and horses revealed similar results (Buhl, Ersboll, Eriksen, & Koch, ; Rovira & Munoz, ; Stewart, Rose, & Barko, ; Trachsel et al., ). Echocardiographic examinations in old dogs revealed a significantly decreased E‐wave and a significantly increased A‐wave compared with young dogs, indicating a decrease in left ventricular (LV) relaxation, increased myocardial stiffness and enhanced late diastolic filling and, thus, indicates an altered diastolic function (Bellows et al., ; Lombard, Evans, Martin, & Tehrani, ; McKeever, Eaton, Geiser, Kearns, & Lehnhard, ; Templeton, Platt, Willerson, & Weisfeldt, ; Urfer et al., ; Urthaler, Walker, Kawamura, Hefner, & James, ).…”

“…Echocardiographic studies in horses showed different results concerning age‐dependent changes. Some authors found significant age‐related changes in echocardiographic B‐ and M‐Mode parameters between different age groups (Rovira & Munoz, ; Trachsel et al., ), but not in indices relative to LV function (Rovira & Munoz, ).…”

Sex‐based limits to running speed in the human, horse and dog: The role of sexual dimorphisms

“…Although there is a paucity of comparative biology studies of sex‐related differences in elite animals that compete in running events, evidence suggests there are minimal anatomical differences in heart and lung sizes of male and female horses and dog breeds when measurements are adjusted for body mass 38 . The sex‐related difference in body mass index of horses 39 and dogs also appears to be blunted relative to the ~11% sex‐related difference observed in world‐class humans 40 .…”

“…33,[35][36][37] Although there is a paucity of comparative biology studies of sex-related differences in elite animals that compete in running events, evidence suggests there are minimal anatomical differences in heart and lung sizes of male and female horses and dog breeds when measurements are adjusted for body mass. 38 The sex-related difference in body mass index of horses 39 and dogs also appears to be blunted relative to the ~11% sex-related difference observed in world-class F I G U R E 2 Running speed for the winning performance (n = 1) by year for the Kentucky Derby in horses (A) and English Derby in greyhounds (B); running speed for the world record (before 1967) or years' fastest 800 m performance in both male and female humans (C) humans. 40 Additionally, though substantial evidence supports that testosterone is strongly associated with sex-based differences in sports performance of humans, 12,33,41 the role of testosterone and androgen hormones may be less definitive among horses and dogs.…”

Fundamentals of arrhythmogenic mechanisms and treatment strategies for equine atrial fibrillation

“…Computer models have demonstrated that atrial enlargement contributes to AF maintenance independently of any other cellular or histological alteration 28 . Atrial enlargement is often secondary to mitral regurgitation in horses, 97,112–114 but exercise training can also increase atrial volume 115–117 and promote regurgitation 118–121 . A multicentre clinical study retained any previous unsuccessful treatment attempt and mitral regurgitation as risk factors for AF recurrence following successful treatment in a multivariate model 5 …”