Cross-country... what are the risks?

Recent years have seen Zimbabwe Eventing gain both popularity and support, leading to our first International 2* in the coming weeks. This aims to educate our followers and clients on the risks of the sport as riders and horses move up through the levels to prevent unneccesary injury.

It is not surprising that eventing places significant strain on the musculo-skeletal system through the demands of both training and competition as horses are required to navigate variable terrain and gradients, in unprecedented conditions at varying speeds.

Commencing cross-country, the horse may already exhibit physiological and structural signs of fatigue even if sub-clinically. This compounded with the athletic prowess needed to accomplish the cross country phase at times results in catastrophic injury (particularly at elite level) seldom seen in dressage or showjumping training or competition.

The most common cause of injury (globally) in cross country competition data has been found to result from hitting fences (35%) with data in Australia suggesting 873 horse falls occurred at fences compared with 90 not at fences.

The second most common cause of injury occurs from horses falling (19%) seeing up to 32% of those injured from the fall and 1.5% being subjected to euthanasia as a result of injuries sustained. The most dangerous fall a horse can sustain is a rotational fall (somersault) resulting from the horse hitting a fence between the knee and elbow, and is likely to result in serious injury to the horse and rider. Alongside the obvious risk resulting from obstacles, the nature and situation of fences is another important factor worth considering.

Retrospective data has suggested an increased risk of falling associated with fences on a downhill slope, or with a ditch in front compared to fences on the flat. Risk of falling also increased with increasing number of fences despite risk of each additional jumping effort decreasing. Fences requiring take-off, landing or both, in water noticeably increase risk of injury in cross country with suggestions of an increase in injury to horses for falls in water compared to land. It has however been suggested that taking off in water lends significant risk to horses in one-day events compared to 3-day events. As can be expected, poor ground conditions are considered to be particularly dangerous in an obstacle course of this rigour and firm going conditions are associated with decreased risk of injury and falling. Furthermore, angled fences are known to contribute significant risk to the event horse, regardless of base spread dimensions, with non-angled fences constituting risk if base spread was more than 2m. Drop landing increases the risk of falling, particularly in one-day events as well as increasing the risk of stifle injury.

Picture: Nicolle Elson and Tenerife

Another significant finding suggests event horses are exposed to much lower exercise intensity during training compared to competition which raises concerns regarding fitness. Depending on fitness level and preparation, unsurprisingly approach speed can be associated with increased risk of falling.

Where is there most danger?

Three day events have unsurprisingly been associated with a higher risk of horse falls (9.5 falls/10000 jumping efforts) than ODE (2.7 falls/ 10000 jumping efforts). The difference in risk of horse falls also varied between novice two-day event competitions (0.0 falls/10000 jumping efforts) and 4* three-day events (14.6 falls/ 10000 jumping efforts). Similarly data from 2002-2006 from Australia suggests novice events see less horse falls compared with CCI**** however the number of falls are proportionally much lower with 4* records showing 5 falls/10000 jumping efforts.

Interestingly Australia only has one 4* event per year. It is therefore possible that the inherent risks of eventing are in fact due to the demands of the sport, and over-exposure is as dangerous and under-exposure to the horse and rider. The proportionally lower number of falls seen in Australia could lend strength to this conclusion because horses are not exposed to more than one 4* per year, however could similarly be due to smaller number of riders competing!

Interestingly, amateur riders were 20 times more likely to fall than professionals, showing that risk to riders alone is potentially higher in amateur events, though injury to horses (and hence more severe injury to riders) is more likely in elite events because of the biomechanical and physiological demand.

Injury Predisposition

The multi-disciplinary nature of eventing results in a plethora of possible injuries, because event horses are prone to common injuries seen across other disciplines. Hindlimb tendon pathology and suspensory ligament injury is of particular prevalence in dressage horses due to the backward shift in centre of mass (CoM), and caudal redistribution of the weight of the horse for prolonged periods of time. Showjumping however, requires the horse to jump large fences with precision while being supple and able to make sharp turns sometimes jumping vertical from stand still. Stresses placed on the hindlimb suspensory apparatus on take-off and the forelimb suspensory apparatus on landing are immense, and hence tendon injury in showjumping is not surprising.

Event horses are at particularly high risk of soft tissue injury during the cross-country phase in training (43.4%) and competition, especially to the superficial digital flexor tendon (SDFT) and suspensory ligament (SL). Soft tissue injuries, especially those occurring while training are often a sign of over-use/ repetitive strain. Another common anatomical site of injury and abrasions, involves the stifle area due to the paucity of soft tissue protecting the cranial aspect.