Oral Lesions and Conflict Behaviour in Dressage Horses

At the 19th International Society for Equitation Science (ISE) Conference in New Zealand, associate professor Janne Winther Christensen presented her recent findings: “Oral behaviour during riding is associated with oral lesions in dressage horses – A field study” with co-author Dr. Mette Uldahl. The talk discussed the relation between oral behaviour and lesions in the corners of the mouth in dressage horses. Her presentation highlighted the importance of understanding discomfort signals and emphasised the need for improved training practices to enhance equine well-being.

Overview of oral lesions in competition

The welfare of competition horses is a topic of ongoing debate both inside and outside of the equestrian community, especially when it comes to bit-related mouth lesions across different disciplines. These injuries have been linked to inappropriate training methods, tight nosebands, and poorly fitting equipment. When riders do not apply and release pressure correctly, this can cause constant pressure on the bit, leading to discomfort or pain. This can lead to the expression of behaviours such as mouth opening, head tossing, or pulling of the reins in an attempt to release the pressure.

Such behaviours are often jointly referred to as conflict behaviours, which are responses to unclear cues, discomfort, or pain. At first, these might be overt responses like shying, bucking or rearing, but over time, they can become more subtle, like tail swishing or mouth opening, especially in high-level dressage horses.

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The presented study investigated if dressage horses with oral lesions from the bit showed a higher frequency of pain or discomfort related behaviours, in comparison to horses competing in the same class without lesions.

Sample and methods

The study was based on data collected during an unannounced inspection for oral lesions at a national dressage competition. The Veterinary Consultant for the Danish Equestrian Federation examined half of the 22 participating dressage horses (i.e., 11 horses: 5 mares, 2 stallions, and 4 geldings) after they had completed their dressage test. The examination looked at the corners of the lips (oral commissure), the gums (bars), and the inside lining of the cheeks (buccal mucosa) on both sides. Any visible lesions (abrasion of the skin) led to elimination from the competition according to the rules from the Danish Equestrian Federation.

Subsequently, an experienced observer watched official video recordings of the competition to assess the horses’ behaviours without knowing the outcome of the oral inspection. Behaviours like mouth opening and other signs of potential discomfort were noted.

Results

Five out of 11 horses had lesions of the skin and/or mucosa at one or both sides of the mouth, leading to elimination from the competition. The pathology of the lesions corresponded to pressure wounds developed by long term bit use. See figure 1.
The number of times the horses opened their mouths (i.e., with separation of the teeth) during the competition ranged from 5 to 59.
Horses with oral lesions opened their mouths significantly more often compared to those without lesions.
Other behaviours such as tail swishing and gait changes were observed but did not show a significant difference between horses with lesions vs without lesions.
No hyperreactive behaviours were observed e.g. flight, bucking, rearing, spooking or bolting.
On average, the horses presented 15 conflict behaviours per minute during their dressage test.

Figure 1: Examples of oral lesions in the 5 dressage horses caused by bits (Photo credit: Danish Equestrian Federation).

Discussion

The researchers stated that this study provided a rare chance to observe behaviour of dressage horses with and without oral lesions during a standardised performance (competition). Usually, inspections occur before the horse and rider enters the competition arena, and horses with lesions are eliminated according to national rules. Further, inspections are usually announced several days ahead of the competition, which allows for riders to withdraw their horses if they observe or suspect lesions. This is good for education and ethics; however, this prevents being able to gather data on the actual prevalence of oral lesions and being able to observe behaviours related to oral lesions during competition.

The researchers found that oral lesions had a high prevalence (45.5%). This is likely reflecting the unannounced inspection and high level of competition, as previous studies have found a higher prevalence of lesions at higher competition levels. This suggests that current inspection protocols may be insufficient to effectively address or reduce the occurrence of oral lesions in competition horses. Therefore, an increase in attention towards horse behaviour during training and competition could improve welfare by promoting training methods that do not cause discomfort and pain.

Conclusion

Dr. Christensen concluded that mouth opening is associated with oral lesions, which indicates equipment and training issues. Increased awareness of behavioural signs can therefore help protect horse welfare by addressing these equipment and training issues before lesions develop”.

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