Hyperflexion in horses lunged at moderate speed and not touched with a whip does not produce a pronounced stress response, researchers in Austria have found.
Lunging the horses with a stretched neck position generated a similar stress response, the study revealed.
In both cases, the stress response, as measured by stress hormones in the animals’ saliva and by monitoring the heart, was found to be less than when horses were transported by road or ridden for the first time.
The only significant difference observed between the two lunging positions related to the temperature of the front (cranial) part of the animals’ necks, possibly indicating that the blood flow was not quite even when the horses were lunged in hyperflexion, the researchers said.
Apart from this one minor difference, the results showed that hyperflexion in horses lunged at moderate speed and not touched with the whip did not elicit a pronounced stress response.
On these findings, there appeared to be no scientific reason to ban the use of hyperflexion, the researchers said.
Nevertheless, Christine Aurich, whose research team at Vetmeduni Vienna – the University of Veterinary Medicine in Vienna – conducted the research, remained cautious.
“Our results show that hyperflexion does not itself harm the animals, but some trainers combine it with forceful and aggressive intervention of the rider over prolonged periods of time,” Aurich said.
“This is a different situation from the one we investigated, so our study should not be interpreted to mean that hyperflexion never has any stressful or negative effects.”
The findings, soon to be published in the Journal of Animal Physiology and Animal Nutrition, add more scientific evidence to the debate around horse welfare and hyperflexion.
Training for equestrian events is strenuous and stressful, both for riders and for horses, the researchers noted, adding that arguments over how best to train horses have raged for centuries. While sports medicine had examined some effects on riders, there has been less work on the stresses suffered by their mounts.
They said the best position of the horse’s head had been extensively debated without any scientific evidence in favour of either of the two main schools: should the neck be fully extended forwards and downwards or should it be “hyperflexed” such that the head almost came into contact with the chest?
Two years ago, the International Equestrian Federation (FEI) was even moved to ban hyperflexion as a result of a petition signed by more than 40,000 people claiming it caused horses unnecessary discomfort.
The FEI made a distinction between hyperflexion (rollkur) by the use of extreme force and what it termed “low, deep and round” (LDR), which essentially achieves the same position without force.
How forceful hyperflexion should be distinguished from permissible LDR training was not clearly stated – instead, a working group has been established to come up with an acceptable definition.
The debate has given rise to considerable emotions on both sides, the researchers said, but it had unfortunately been characterized by a lack of scientific evidence.
Mareike Becker-Birck, in Aurich’s research group, set about comparing the levels of stress shown by horses trained on the lunge with their necks either extended forwards or fixed in hyperflexion.
Stress was assessed by monitoring the levels of stress hormones in the animals’ saliva and by following the heart rate and the fluctuations in heart rate exhibited before, during and after training.
In addition, the surface body temperature was measured before and after the experiment. None of the horses suffered any obvious discomfort during the training, which was undertaken without the use of a whip.
The horses showed an increase in stress hormones in their saliva, an increase in heart rate and a decrease in heart rate variability when they were trained. The changes presumably stemmed from a combination of physical activity and the normal stress responses.
The level of stress incurred by the animals was not particularly high – the change in hormones in the saliva was actually less than when horses are transported by road or ridden for the first time.
Importantly, the effects were the same irrespective of whether the animals were lunged under hyperflexion or under “classical” conditions with their necks extended.
The research was carried out at the Graf Lehndorff Institute for Equine Science, a joint research unit of the University of Veterinary Medicine, Vienna, Austria, and the Brandenburg State Stud at Neustadt (Dosse), Germany.
The paper, entitled “Cortisol release, heart rate and heart rate variability, and superficial body temperature, in horses lunged either with hyperflexion of the neck or with an extended head and neck position”, by Mareike Becker-Birck, Alice Schmidt, Manuela Wulf, Jörg Aurich, Armgard von der Wense, Erich Möstl, Reinhold Berz and Christine Aurich is published in the current issue of the Journal of Animal Physiology and Animal Nutrition.
The abstract of the scientific article is online.