Original ResearchEvaluation of Indicators of Weight-Carrying Ability of Light Riding Horses
Introduction
The optimum weight a horse can safely carry depends on a variety of physical traits. These may include the horse's size, conformation, body condition, age, duration of the work to be done, as well as speed at which the work is being performed. A few methods are used to help estimate how much weight a horse can safely carry; however, little research can be found to justify these methods.
Historically, the most common recommendation states that the total weight a horse can carry should not exceed 20% of the horse's body weight. This policy may have been based on the 1920 U.S. Calvary Manuals of Horse Management, where the recommended collective weight of rider and gear was not to exceed 20% of the total weight of the horses. Comparably, a more recent study of 360 endurance race horses, primarily of Arabian breeding, evaluated horse and rider weight relationships. They analyzed weight loads as horse body weight independent of rider weight, rider weight independent of weight of the horse, and a rider weight ratio calculated as rider weight divided by the weight of the horse. They concluded that conditioned horses were able to carry 20 to 30% of their body weight for 100 miles.1 In a follow-up study conducted by the same group of researchers, 193 endurance race horses were evaluated for weight loads as described in the previous study. They found that horses with increased body weight without a proportional increase in cannon bone circumference had increased incidence of biomechanical failure, for which the horse did not successfully complete the race.2
The amount of bone that a horse possesses also has been used as a method to help determine the amount of weight a horse can carry. There are a multitude of studies using the equine third metacarpal bone to evaluate skeletal biomechanics relationships, which include bone strength in relation to bone fracture, tension, stress, and elasticity.3, 4, 5 Ultrasound also is used as a tool for assessment of bone quality in horses6 and humans.7 Based on a study conducted by Bynum et al,8 a simple noninvasive method for evaluating the amount of bone is by measuring the circumference of the third metacarpal bone midway between the carpal−metacarpal joints, where the recommended circumference is estimated to be 20 cm per 454.5 kg horse body weight. Although this method does not evaluate the actual mineral content of the bone, which is the primary determinant of skeletal bone strength, it can be used as a quantitative measure of the amount of bone.
When evaluating weight-carrying ability of the riding horse, it is important to take into consideration the conformation of the horse. It was determined by a German scientist in 1941 that the horse carries approximately 60% of its body weight on its front legs and 40% on the hind legs; therefore, the center of gravity of a riderless horse would be located at a point just behind the withers near the heart girth.9 There are certain conformational qualities that make it easier for the horse to carry weight on its back. It is a widely held belief among top endurance competitors that loin width is a highly desirable quality in endurance prospects (personal correspondence). The loin of the horse is defined as the pivot point of the horse's back and is the area between the last rib and the croup (crest of the ilium). The width of the loin ends where the ribs start to curve downward. No studies have evaluated loin width as a possible indicator of weight-carrying capacity in the horse.
Plasma lactate concentrations and heart rate are reliable variables used to evaluate the workload of a horse.10 The activity of serum creatine kinase (CK) has been used as an indicator of muscle damage and the association of postexercise muscle soreness in humans.11 The objective of this study was to determine whether cannon bone circumference, loin width, and horse height could be used as indicators of the weight-carrying ability of the light riding horse.
Section snippets
Horses
Eight mature horses of light horse type were used, 1 mare and 7 geldings, age 6 to 18 years and weighing 391 to 625 kg. All horses were used as lesson horses but had been pasture rested for a period of 4 months before the study. During the study, horses were housed individually in 4 × 4 m stalls with daily turnout. All horses received a daily ration of timothy/alfalfa mixed hay (13.66% CP, DM; 8-10 kg/day) and a pelleted concentrate (14.18% crude protein, dry matter; 3 kg/day) divided between
Results
Table 1 shows the physical data for each horse. There were no changes in body weight during the study. Environmental temperature and relative humidity data for the exercise tests are shown in Table 2. A greater (P < .05) work rate was elicited when horses carried 25 and 30% of their body weight (Fig 1). Heart rates before exercise did not differ significantly among treatments (Table 3). Heart rates, respiration rates, and rectal temperatures differed (P < .05) when the horses carried 25% and
Discussion
To our knowledge this is the first study of this type. In this study, a subjective scoring system of assessment of muscle soreness and tightness was employed as a guide in the assessment of chosen variables of body weight, horse height, cannon bone circumference, and loin width on their usefulness as indicators of weight-carrying ability in light riding horses. The submaximal mounted standard exercise test of the current study was designed to simulate a 45-minute working session of an
Acknowledgments
This study was funded by The Research, Creative, and Other Scholarly Activities (RCOSA) grants.
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2021, Journal of Equine Veterinary ScienceCitation Excerpt :This indicates that there could be a high frequency of welfare concerns in the non-racing population, because muscular pain and lameness are common concerns of horse owners, with owners citing concurrent poor performance or misbehaviors in horses diagnosed with lameness [10,11]. Post-exercise muscle soreness and increased serum creatinine kinase activity were induced in horses carrying 30% of their bodyweight during a moderate-intensity 45 minute exercise protocol designed to mimic a riding lesson [12], while lameness was induced in previously-sound horses undertaking a 30 minutes dressage test, when carrying more than 17.3% of bodyweight [13]. These studies indicate a potential for muscle damage and poor welfare of horses carrying > 17% of bodyweight during moderate intensity exercise, a level of exercise that more horses participate in than racing [14].
Gymnastic Training of Hippotherapy Horses Benefits Gait Quality When Ridden by Riders with Different Body Weights
2020, Journal of Equine Veterinary ScienceCitation Excerpt :The authors concluded that the maximum permissible load should be below 43% BWR in these ponies [42]. Relating conformation and performance, Powell et al [40] reported that horses with wider loins and greater cannon circumference showed less back soreness after carrying heavy riders. Ponies are generally more stocky than horses and this likely contributes to the fact that Taishuh ponies and Icelandic horses are able to carry relatively heavier weights than larger breeds of horses without a change in stride symmetry.
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2020, Journal of Equine Veterinary ScienceThe Effect of Season on Muscle Growth, Fat Deposition, Travel Patterns, and Hoof Growth of Domestic Young Horses
2020, Journal of Equine Veterinary ScienceCitation Excerpt :In addition, ultrasonography can also be used to estimate adiposity and is more accurate than body condition score (BCS) in predicting fat tissue over the entire body in horses, especially in estimating localized fat tissue [9]. As the greatest part of the forelimb to support body weight (BW), the cannon bone has the greatest growth rate in length from birth to 10 weeks of age, after which length remains stable (Quarter Horse data [10,11]. Circumference of the front cannon bone can also be used to estimate the strength and mineral content of the bone [12].
Indicators of stress in equitation
2017, Applied Animal Behaviour ScienceCitation Excerpt :00 Other stress-indicators that have been used in horses include (see also Table 1) plasma or blood lactate levels (Powell et al., 2008; Fazio et al., 2013; Munsters et al., 2013), plasma ascorbic acid (Baucus et al., 1990), prolactin (Colborn et al., 1991), iodothyronine (Medica et al., 2011), oestradial-17β (Medica et al., 2011), serum creatin kinase activity (Powell et al., 2008), packed cell volume (Sloet van Oldruitenborgh-Oosterbaan et al., 2006), ACTH (Ferlazzo et al., 2012; Fazio et al., 2013) and plasma β-endorphin (McCarthy et al., 1993; Gillham et al., 1994; McGreevy and Nicol, 1998; Ferlazzo et al., 2012) as well as various other parameters for example, related to blood chemistry (e.g., De Rantere et al., 2007) and immune function (Malinowski et al., 2006). However, all these parameters are predominantly linked to physiological workload or other physiological processes in the body, and it is questionable to what extent, if any, these parameters can serve to detect psychological stress.
Refereed