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Hyperflexing horses' necks – meta-analysis and cost-benefit evaluation

Authors:

Abstract

A review of the scientific literature identified 55 articles dealing with the effects of equine head and neck postures (HNP) on welfare (n=42) and/or gymnastic outcomes (n=35) such as kinematics, muscle activity, respiratory related issues or overall workload. In the dataset for the meta-analysis we coded overall results of the individual studies as follows: positive (1), contradictory or insignificant (0) or negative (-1) influences on a) welfare and b) gymnastics. Information on the reported features of hyperflexion (e.g., degree and duration), the horses (e.g., level of dressage training), and quality and design of the study (e.g., whether or not the study's conclusions were supported by data) was also integrated into the dataset. The significant majority of studies (88%; Z= 4.94; P<0.0001) indicated that a hyperflexed HNP negatively impacts welfare. Only one study suggested positive effects on welfare. Reasons for compromised welfare included impeded ventilation, pathological changes in the structures of the neck, impaired forward vision, and stress and pain due to these factors as well as the rider intervention necessary to achieve the posture. An across-study analysis using a mixed model revealed that the probability of a study reporting negative welfare effects was unrelated to any of the investigated factors such as horses' familiarity with the posture, level of dressage training, duration of the HNP or size and quality of the study (all P>0.1). While gymnastic benefits were described in 26% of the studies, a similar proportion of studies (23%, P>0.1) detected undesirable gymnastic consequences of a hyperflexed HNP. The remaining studies (46%) described insignificant or contradictory effects on gymnastics. Desired gymnastic effects included higher dressage scores, a larger range of motion in the back or legs or an increased overall workload, while undesired gymnastic effects included lower dressage scores, increased activation of lower neck muscles and reduced oxygen supply due to obstruction of upper airways. Studies conducted on highest level dressage horses and on horses familiar with a hyperflexed HNP were more likely to describe gymnastic benefits than studies conducted on non-dressage horses or those unfamiliar with the posture (both P<0.05). These findings question whether any desirable effects of this training method are based solely on biomechanical relationships. Instead, the effects may be the result of horses learning to respond to the cues associated with hyperflexed HNPs with desired changes in posture or movements. LP: Based on a comprehensive review of the scientific literature, the presumed gymnastic benefits of training horses in a hyperflexed head and neck posture are by far outweighed by both undesired gymnastic effects and reduced equine welfare. A statistical analysis across the studies revealed that negative effects on welfare prevail regardless of the circumstances under which hyperflexion is practiced.
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Oral Presentation Abstract 1
Hyperflexing horses’ necks meta-analysis and cost-benefit evaluation
Uta König v. Borstel* (University of Göttingen, Germany), Kathrin Kienapfel (University of Bochum,
Germany); Andrew McLean (Australian Equine Behaviour Centre, Australia); Christina Wilkins (PO
Box 99, Rosewood, Queensland 4340, Australia); David Evans; Paul McGreevy, Paul (University of
Sydney, Australia)
koenigvb@gwdg.de
A review of the scientific literature identified 55 articles dealing with the effects of equine head and
neck postures (HNP) on welfare (n=42) and/or gymnastic outcomes (n=35) such as kinematics,
muscle activity, respiratory related issues or overall workload. In the dataset for the meta-analysis
we coded overall results of the individual studies as follows: positive (1), contradictory or
insignificant (0) or negative (-1) influences on a) welfare and b) gymnastics. Information on the
reported features of hyperflexion (e.g., degree and duration), the horses (e.g., level of dressage
training), and quality and design of the study (e.g., whether or not the study’s conclusions were
supported by data) was also integrated into the dataset. The significant majority of studies (88%; Z=
4.94; P<0.0001) indicated that a hyperflexed HNP negatively impacts welfare. Only one study
suggested positive effects on welfare. Reasons for compromised welfare included impeded
ventilation, pathological changes in the structures of the neck, impaired forward vision, and stress
and pain due to these factors as well as the rider intervention necessary to achieve the posture. An
across-study analysis using a mixed model revealed that the probability of a study reporting
negative welfare effects was unrelated to any of the investigated factors such as horses’ familiarity
with the posture, level of dressage training, duration of the HNP or size and quality of the study (all
P>0.1). While gymnastic benefits were described in 26% of the studies, a similar proportion of
studies (23%, P>0.1) detected undesirable gymnastic consequences of a hyperflexed HNP. The
remaining studies (46%) described insignificant or contradictory effects on gymnastics. Desired
gymnastic effects included higher dressage scores, a larger range of motion in the back or legs or an
increased overall workload, while undesired gymnastic effects included lower dressage scores,
increased activation of lower neck muscles and reduced oxygen supply due to obstruction of upper
airways. Studies conducted on highest level dressage horses and on horses familiar with a
hyperflexed HNP were more likely to describe gymnastic benefits than studies conducted on non-
dressage horses or those unfamiliar with the posture (both P<0.05). These findings question
whether any desirable effects of this training method are based solely on biomechanical
relationships. Instead, the effects may be the result of horses learning to respond to the cues
associated with hyperflexed HNPs with desired changes in posture or movements.
LP: Based on a comprehensive review of the scientific literature, the presumed gymnastic benefits
of training horses in a hyperflexed head and neck posture are by far outweighed by both undesired
gymnastic effects and reduced equine welfare. A statistical analysis across the studies revealed that
negative effects on welfare prevail regardless of the circumstances under which hyperflexion is
practiced.
Article
The impact of head and neck position (HNP) on horse welfare has received much attention in the scientific literature within the last two decades. Studies have identified physiological and behavioral signs of distress in horses ridden for prolonged time in an HNP with their noseline behind the vertical (BTV), which may compromise their welfare. The objective of this study was to compare potential differences of HNPs shown in horse sales photographs advertised in an Australian horse sales magazine (Horse Deals) from the years 2005 and 2018. In addition, factors potentially impacting HNPs, such as type of tack presented in (e.g., noseband type), riding discipline, and competition experience of the horse, were investigated. The sample population (n = 570) comprised horses ridden with headgear and bit in walk, trot, or canter/gallop, advertised in an Australian horse sales magazine. Issues from April 2005 and October/November 2018 were selected. Head and neck position was categorized as BTV, on the vertical (OV), slightly in front of the vertical (IFV), or extremely in front of the vertical (EIFV; any HNP >30° IFV). Data were analyzed using the chi-squared test and post hoc testing via a multiple regression approach through SPSS and test of proportions via the Z-score calculator for two independent population proportions. Analysis of combined data from years 2005 and 2018 showed 47.0% (n = 570) of the horse sample population were advertised with HNPs BTV. Behind-the-vertical HNP was observed as the predominant HNP (57.8%; n = 268) in the warmblood/eventers/show/performance (WESP) category (P < .0005). In 2005, 53.4% (n = 303) of the sample population were ridden BTV compared with 39.7% (n = 267) in 2018 (P < .001), 12.9% (n = 303) were OV in 2005 compared with 15.0% (n = 267) in 2018 (P > .05), and 10.9% (n = 303) were IFV in 2005 compared with 27.3% (n = 267) in 2018 (P < .0004). These results suggest a positive development with fewer vendors/riders selecting images where the horse’s nose was BTV. However, this may be explained by the larger proportion of horses advertised in the WESP category in 2005 (63.0%; n = 303) versus 2018 (28.5%; n = 267), and the WESP category predominantly comprised of dressage, jumper, and eventing horses. In addition, the reduction of HNPs BTV from 53.4% (n = 303) in 2005 to 39.7% (n = 267) in 2018 could be attributed to the observation that in 2018, a larger proportion of horses were listed in categories that do not require the horses to be worked with a flexed HNP referred to as “on-the-bit” (e.g., western, endurance, Australian sStock horses). The HNP BTV remains preferential by a substantial proportion of the horse-owning public when advertising horses for sale, particularly in disciplines where the horse is worked in a flexed HNP or “on-the-bit.”
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