A link between continual mouth opening and the presence of oral lesions has been identified in dressage horses.
A Danish study, published in October and presented at the International Society for Equitation Science 2024 conference, aimed to investigate if horses competing at upper national level with oral lesions differed in behaviour compared to horses without lesions.
The research was based on data collected at a routine, but unannounced, inspection of 11 randomly selected horses’ mouths immediately after an intermediate I class at a national competition. Five of the 11 had “abrasion of the skin and/or mucosa” at one or both corners, and were eliminated from the competition.
The inspections were carried out by the federation’s then veterinary consultant and the study’s co-author Mette Uldahl, who has since joined Animal Protection Denmark as chief consultant.
Co-researcher Janne Winther Christensen, who was unaware of the outcome of the oral inspection, analysed the behaviour of the horses from footage of the competition to record mouth opening, tail swishing, breaking of gait, head movements and hyper-reactive behaviour.
It was found that the frequency of mouth opening ranged from five to 59 times in the 11 horses, and horses with lesions had a “significantly higher frequency” of mouth opening compared to those without lesions. The frequency of other behaviours did not significantly differ between the groups.
Ms Winther Christensen told H&H the five horses with lesions were given high scores by the judges and some would have been placed had they not been eliminated.
“We know that the most frequently observed conflict behaviours in dressage horses are mouth opening and tail swishing, and it appears that horses can show a lot of these behaviours and still win,” said Ms Winther Christensen, adding that this is “concerning”.
Ms Winther Christensen added that it is difficult to know if the riders were aware of the lesions beforehand, but said they were not new – and lesions are “fairly simple to see in horses by looking at the mouth”.
“Usually lesions are pressure wounds that develop over time, they don’t happen suddenly. Even if riders have someone who tacks up their horse, it is still their responsibility to check that the horse is OK,” she said.
Ms Udahl said this research is part of a portfolio of work she has been carrying out on oral lesions since 2014, with the aim of developing future protocols.
“Of the thousands of horses I’ve examined over the years, there has never been one horse with an acute bleeding lesion – they have all been chronic pressure wounds, where the horse leans too heavily on the bit as a strategy to solve something else,” she said.
“Our research is focused on mapping the horse language and we need to be more observant, what do they tell us? If we can predict a link between oral lesions and mouth opening, then it’s better to eliminate riders before they start and for them to figure out what is the key to the problem.
“There’s no doubt that there is a lot of work to be done and at top-level competitions we need to acknowledge the behaviour of these horses. We don’t do this work to blame individuals, we do it to understand what is going on and to ensure that at governance level we can protect horses by being knowledgeable of human nature, and build the sport so that the incentive to ride horses with oral lesions is not there any longer.”
A Danish equestrian federation spokesperson told H&H the findings from the study, which was conducted in 2022, made it a “top priority” for the federation to conduct further inspections across all levels in dressage competitions, before horses enter the arena rather than after.
The spokesperson said this change in approach since the study has “significantly reduced” the occurrence of oral lesions identified; from 659 inspections in 2023, 11 horses were eliminated, and of 1,689 inspections in 2024, 37 horses were eliminated.
“In percentage terms, the proportion of horses eliminated during horse inspections is now below 2.5%. That is still too much, but it is an improvement from the first initial inspections,” he said.
“The goal is to have no horse eliminated due to welfare concerns. From the 2024 inspections the horses eliminated were entered by amateurs and in competitions medium level and below.”
The spokesperson said the federation is “committed to advancing horse welfare at all levels” and as new knowledge is gained, the federation “continuously” updates its rules to align with this.
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