Researchers successfully identified a subset of elite eventing horses at increased risk of a poor cross-country performance, after applying a ridden horse behaviour scale.
The study, reported in the journal Equine Veterinary Education, began with a pilot study on a convenience sample of 35 horses competing on the second day of dressage at the Burghley CCI 4* (now 5*) event in 2018.
The main study a year later involved 70 horses warming up for the dressage phase of the CCI 5* Badminton horse trials in May 2019; and 67 horses warming up in similar fashion for Burghley four months later.
In all cases, each horse was observed for 10 to 12 minutes under saddle during their dressage warm-up by equine researcher Dr Sue Dyson using the Ridden Horse Pain Ethogram (RHpE).
Dyson led research about three years ago that led to the development of the RHpE, and is extensively trained in its use.
The RHpE comprises 24 behaviours, each with strict definitions, that occur more frequently in a horse with musculoskeletal discomfort compared with a non-lame horse.
During the 10 to 12 minutes, the observer records the number of behaviours present.
They include the likes of mouth opening with separation of the teeth for at least 10 seconds, repeated head tilting, persistent tail swishing, an intense stare for five or more seconds, spooking, bucking, rearing, tail clamping, repeated tongue exposure, and putting the ears back for more than five seconds.
The presence of at least 8 of the 24 behaviours is considered a reliable indicator of the presence of an underlying musculoskeletal problem. The higher the tally, the greater the likelihood that the horse has musculoskeletal discomfort which may compromise performance.
It has previously been shown that the most frequent score in non-lame horses is 2/24.
Dyson also noted whether she considered the horse was sound, or showed some lameness (episodic or continuous), restricted hindlimb impulsion, or gait abnormalities in canter, such as lack of a suspension phase.
The pilot study indicated that an RHpE score of seven or more in highly trained horses competing at 5* star level was more reliable for identifying those whose performance might be impaired by musculoskeletal discomfort than the score of eight previously used for the wider sport horse population.
The resulting RHpE scores for the top-level eventers compared to final results in terms of dressage penalties, cross-country performance, showjumping penalties and final placings.
RHpE scores for the 137 horses in the main study ranged from 0 to 9 out of 24.
Among those assessed as sound (non-lame) by Dyson, the median score was 3. Among those with gait abnormalities or lameness at the trot or canter, a median score of 5 was recorded.
Dyson and her fellow researcher, Dr Andrea Ellis, found a moderate positive correlation between dressage penalty scores and the RHpE score.
However, the correlation was far more pronounced in the more physically demanding cross-country phase. Ten of the 17 horses (59%) with an RHpE score of 7 or more failed to complete the cross-country, compared with 33% (39 out of 117 horses) with a score below 7.
There was no relationship between the RHpE score and showjumping performance. However, there was a significant relationship between total RHpE score and final horse placings, with horses having higher RHpE scores being worse placed than horses with low RHpE scores.
Horses identified with lameness or gait abnormalities at the canter had significantly higher RHpE scores compared with other horses.
Dyson and Ellis also found a strong correlation between the RHpE scores for horses who competed at both events.
The most frequent behaviours observed were front of the head behind a vertical position for 10 or more seconds, repeated head tilting, the mouth being held open with separation of the teeth for 10 or more seconds, an intense stare for five or more seconds, and repeated tail swishing.
The pair concluded that horses at three-day-events can pass the preliminary in-hand horse inspection, but show gait abnormalities when ridden, highlighted by the behavioural changes assessed with the RHpE.
“Gait abnormalities may compromise dressage and cross-country performance in some horses and influence the final placing.”
Although there are a variety of reasons for a horse and rider not to complete the cross-country phase, including falls, cumulative refusals or retirement, the results indicate a strong association between the RHpE score and failure to complete. This indicates that underlying musculoskeletal discomfort may be a contributory cause.
“The RHpE could facilitate identification of horses which may benefit from veterinary investigation and treatment, potentially resulting in improvement in both performance and equine welfare.”
Application of a Ridden Horse Pain Ethogram to horses competing at 5-star three-day-events: Comparison with performance
S. Dyson and A. D. Ellis
Equine Veterinary Education, December 4, 2020, https://doi.org/10.1111/eve.13415
The abstract can be read here.