Chapter 117Lameness in the Three Day Event Horse

Sport of Eventing

The sport of eventing generally is considered the most all-around test of a horse’s athletic ability, and therefore the horses tend to be jacks-of-all-trades rather than excelling in any one particular area. The competition consists of three disciplines, namely dressage, show jumping, and cross-country, with the latter being the most influential phase. The Three Day Event or Concours Complet International (CCI) is the pinnacle of the sport (Figure 117-1) and is run over 4 days: 2 days of dressage, followed by a day for the speed and endurance phases and a day of show jumping. In the traditional long-format event the speed and endurance test consists of roads and tracks at trotting speed, a steeplechase, and the actual cross-country phase over fixed obstacles. This is a severe athletic test, and horses normally compete in only two or maximally three such competitions in a year. Since 2004 a “short format” Three Day Event has been introduced, which excludes the steeplechase and endurance phases but leaves the cross-country phase. This is cheaper to stage and potentially requires a smaller site on which to run the competition. At CCI**** level the course must be 6720 to 6840 m in length, with up to 45 jumping efforts at an optimum speed of 570 mpm, to therefore be completed within 11 to 12 minutes. It has resulted in some horses competing in three or occasionally four such competitions in one year.

Fig. 117-1 Example of a cross-country fence at CCI**** level.

(Courtesy Kit Houghton Photography, Bridgewater, Somerset, United Kingdom.)

CICs (international One Day Events), One Day Events or Horse Trials, compress the same disciplines into a shorter time frame but without the roads and tracks and steeplechase phases. The distance and thus time for the cross-country phase are also much shorter, and there are fewer jumping efforts, so that many such competitions may be completed in a season. For most advanced horses, One Day Events are used as training for the Three Day Events, although a large number of recreational competitors aspire to compete in only One Day Events. There are an increasing number of relatively high–prize money CICs, encouraging international level horses to compete more frequently. The emphasis of this chapter is the Three Day Event horse, because the extreme demands placed on this horse give characteristic patterns of lameness, whereas the novice One Day Event horse can be considered a standard riding club or recreational horse from a veterinary point of view.

Eventing is an established Olympic sport and a substantial equine industry. The highest grade of competition is the four-star event (CCI****). Traditionally these have been the English events of Badminton and Burghley, although there are now more elite level competitions around the world including Lexington, Kentucky, United States and Lumhulen, Germany. The sport has a high-risk element for rider and horse, and a noticeable recent trend has been to try to make courses safer, with the introduction of fences with frangible pins to try to minimize the frequency of rotational falls.

The sport includes substantial veterinary involvement. During a Three Day Event, the horse is examined by the official veterinarians on arrival, the day before commencing the dressage, before and after the cross-country, and the morning before show jumping. The horse must be deemed fit to compete—that is, the horse must be sound—throughout the competition, and thus any orthopedic disorders are of great clinical significance. A mild degree of hindlimb gait asymmetry may be acceptable to the Inspection Panel, but any noticeable forelimb lameness normally is not permitted.

Horse Types

Because the Three Day Event places great emphasis on the horse’s speed and stamina, there is a preference toward the Thoroughbred (TB) or predominantly TB crossbreeds. A substantial proportion of horses are of uncertain or unknown breeding. Exceptions have been notable, but Warmbloods and classic Irish hunter types normally do not have the endurance required at the top level. Such horses often may do extremely well at the lower levels, however, because they move and jump better than the pure TB. Figure 117-2 demonstrates what could be considered the ideal modern eventing stamp, a highly successful New Zealand TB. A horse’s ability and mental aptitude are the most important determinants, and other body types are successful (Figure 117-3). An average ideal size would be 16.2 hands, but the rules are not hard and fast. The short-format Three Day Event has perhaps slightly reduced the emphasis on pure galloping ability, and because the courses usually have the same number of jumping efforts, sometimes in a shorter course, there is a need for the horses to be quick and nimble.

Fig. 117-2 An ideal modern eventing stamp. This 16.1-hand–high New Zealand Thoroughbred gelding was an individual Olympic and World Championship gold medalist.

(Courtesy Badminton Speciality Feeds, Oakham, Rutland, United Kingdom.)

Fig. 117-3 Example of a successful but tall and hunter-bred horse. This 17-hand–high gelding Thoroughbred-cross Irish draft horse was a Badminton CCI**** winner and Open European Championship Team gold medalist.

(Courtesy Kit Houghton Photography, Bridgewater, Somerset, United Kingdom.)

The financial value of event horses is considerably lower than that of racehorses, show jumpers, or dressage horses, so any horse with outstanding ability in one of these phases is likely to be used in that sport first. If the horses do not succeed, then they may be tried as potential event horses. These horses bring with them any injuries they may have accumulated, but because of the different stresses imposed during eventing, this may not be a problem. For example, event horses tolerate low-grade carpal pathological conditions from previous race training. A small number of horses are bred specifically for eventing. Stallions generally are considered to lack the courage required to compete at the top level, and because the horse takes a number of years to reach its peak, choosing proven sires is a problem. The predominantly TB Irish sports horse and the relatively larger-boned New Zealand and Australian TBs are sought after.

Event horses normally commence dressage and show jumping training at 4 years of age and start competing in prenovice and novice One Day Events from the age of 5. Depending on the horse’s ability and rider’s skill and patience, a horse usually competes in its first (graded as a CCI* or CCI**) Three Day Event at 6 to 7 years of age. A substantial proportion of horses do not have the ability, courage, or physical durability to proceed beyond the CCI** or CCI*** level to the top grade of CCI****.

Influence of the Sport on Lameness

Event horses are generally skeletally mature when they commence training and are not trained at the same speed or intensity as racehorses. They therefore have different patterns of injury, although most of the problems are still related to training. Primary long bone pathological conditions are rare. Soft tissue injuries such as tendonitis are common and often career limiting. The amount of endurance training necessary produces repeated cyclic loading, and problems such as osteoarthritis (OA) are common. The other subset of event horse injuries is acute traumatic injuries sustained during competition. Because the horses are jumping large fixed obstacles at speed, they are prone to falls and to direct traumatic fractures. The short format does not seem to have led to a dramatic difference in the type or incidence of injuries. Horses may tolerate low-grade soft injuries better than with the long format, and in the long run there might be a decrease in the incidence of injuries.

Fence design has changed in recent years. Square-shaped fences are avoided, and rounded top contours are now more common. These fences give horses more leeway to correct mistakes and cause less severe direct impact trauma. The fences may be 1.2 to 1.4 m high, with a 2-m spread and a 2-m drop, so substantial strain can be placed on the supporting structures of the limbs on landing. The quality of the terrain also appears to have an important impact on the incidence of lameness problems. The competitions are run predominantly on turf, the nature of which depends on the soil type, local weather, and management factors. At the lower level, financial constraints generally preclude much improvement on the quality of the ground, but some of the top events try to maintain a permanent track that is tended carefully.

The prolonged period and intensity of training required for horses to reach an elite level means that those horses not metabolically or physically suited to the sport are selected out. For instance, few elite horses have recurrent exertional rhabdomyolysis or navicular syndrome. Three Day Events are regulated by the Fédération Équestre Internationale. A strict medication control program is enforced and permits only emergency medication at the competition after official veterinary approval or the use of a small number of permitted forms of medication, including antibiotics, rehydration fluids, and preparations for treating gastric ulcers.

Training Methods

Event horses train in all three disciplines, with the actual methods varying greatly among riders. A complete description of training methods is available elsewhere.¹ Most competing horses have natural cross-country ability, so little time generally is spent on training for this, because the progression of competitions provides sufficient experience. Event horses normally are selected for natural jumping action, but jumping technique during the cross-country phase is different from that needed for show jumping. Therefore event horses may not be as careful when show jumping and can have a tendency to touch poles. Most event horses are show jumped regularly, especially during the off season. The event horse’s weakest link is usually the dressage phase. The movements required are no more than a medium level of pure dressage, but the different breeding and level of fitness of these horses means that the major challenge can be to control the horse’s temperament. Most of the skills training revolves around dressage, and a high standard now is required to be competitive at the top level.

Fitness training is a major component of the preparation for a Three Day Event and is where most orthopedic damage is incurred. The horse is likely to undergo a 3- to 4-month training period for the target Three Day Event. Training methods vary greatly among riders and often depend on local factors such as the availability of hills for trotting or all-weather gallops. Restricting the horse to training solely on an artificial surface is not advisable, because this seems to predispose the horse to injury when the horse actually competes on a natural surface.

Event horses normally receive a 6-week initial period of walking and trotting on the roads, and then commence cantering exercise. Different riders vary in their use of conventional or interval training but usually peak the quantity of work at around three canters of 8 minutes, or shorter if a hill is available. The quality of the work usually is increased closer to the Three Day Event to include faster work. One Day Events are used to monitor the horse’s fitness and as additional training. The dressage and jumping training also substantially contributes to the fitness regimen. Older, experienced horses can get to major competitions with relatively few preparatory runs in comparison with less experienced horses, making it easier to manage low-grade injuries.

The majority of riders have not substantially reduced the intensity of their training for short-format competitions. The initial impression was that horses were finishing short-format competitions more tired than at a long-format competition. This was unexpected because of the lower overall effort of the shorter format. It may have been a result of the more intense nature of jumping the same number of fences in a shorter course. There may also have been an element of riders not preparing their horses as intensively for what was thought to be a less demanding competition. A study comparing cross-country recovery rates at a CCI** in long and short formats showed no significant difference between the two groups.²

Conformation and Lameness

Although the horse’s stamp may vary the basic conformation must be correct. Eventing is unforgiving to conformational defects compared with show jumping and dressage. The general principles are the same as for any equine athlete. Serious conformational defects include being back at the knee, having upright pasterns and hocks, and having a moderate or severe toed-out conformation. Of slightly lesser importance are having a long or short back, being over at the knee, or having long, sloping pasterns. Defects such as offset knees and a slight-to-moderate toed-in conformation seem to be less important. A good foot conformation is always desirable, but many event horses have the TB trait of weak feet with collapsed heels.

The prepurchase examination for a young event prospect with hopes of a Three Day Eventing career is likely to be strict. The conformation should be assessed critically at this stage. Although the horse may have sufficient talent, defects in conformation may not allow it to stand up to the 5 or so years of training necessary to reach the top level of the sport. Conversely, it is possible to be more lenient in the interpretation of subtle problems when performing a prepurchase examination on an older, experienced horse. The horse’s competitive record should be assessed carefully, because advanced horses are likely to have accumulated wear-and-tear changes during an extended career. Any conformational or subtle soundness queries can be addressed in light of the horse’s proven ability to perform its task.

Lameness Examination

My standard approach is described, and the regions requiring particular attention and the most rewarding procedures are outlined for horses with subacute or chronic lameness problems. Care should be taken to palpate all limbs and the back thoroughly, because many concurrent or compensatory injuries can be found that way. Because many problems are subtle, the horse should be examined on a variety of surfaces and at different gaits.

Particular attention should be paid to the feet. The size, shape, and conformation should be assessed in relation to the size and breed of horse. The suitability of the shoe type for that horse should be determined, because farrier preference may have been influenced by fashion. The fit of the shoe should be correlated with stage in the shoeing cycle. Fortunately, the trend is to move away from the traditional problem of shoeing the horse short and tight at the heel. The hoof should be palpated for heat and any cracks or defects. The sole should be pared and hoof testers carefully applied over the entire solar surface, assessing the solar compliance and any pain response. Horses with recurrent bruising associated with soft soles may not have demonstrable pain on examination, but the lack of solar rigidity is clearly evident. Percussion may be helpful in a small proportion of horses. An increased digital pulse amplitude can be helpful in determining the presence of any inflammation in the foot and is especially important if the amplitude is asymmetrical in a limb or between feet. A subtle increase in digital pulse amplitude is best evaluated after trotting the horse in hand on a hard surface.

The horse should be palpated carefully for distention of the distal interphalangeal (DIP) and metacarpophalangeal or metatarsophalangeal (fetlock) joint capsules. The range of joint flexion and any resentment to flexion should be assessed carefully. Particular attention should be paid to the palmar metacarpal structures for presence of subtle, diffuse filling and any discrete swelling, heat, or pain in the tendonous or ligamentous structures. Owners and riders of event horses tend to be thorough in their own palpation of this region and often know the normal contours of their horse well. However, they often are misled by distention of the medial palmar vein or diffuse swelling from a more distal inflammatory lesion.

In the hindlimbs, pain on palpation over the cunean bursa and in response to the Churchill test should be determined. The medial femorotibial and femoropatellar joint capsules should be palpated to detect distention. The muscle tension in the back and hindquarters should be assessed carefully. Trigger points and painful foci should be determined, and the range of spinal flexibility in response to running a blunt object along the back should be assessed.

During the static examination the horse should be assessed for symmetry. The horse’s condition and degree of muscling should be assessed in relation to its level of fitness. The freeness of stride, dynamic foot placement, and foot flight arcs should be assessed at the walk. At the trot any head nod and the range of gluteal excursion should be assessed to determine any lameness. Lunging in a circle on a hard surface frequently is used to exacerbate subtle lameness. However, it is also critical to see the horse lunged on a soft surface, a portion of the lameness examination that often is omitted. Different lameness conditions may be evident on different surfaces, and this comparison is valuable. For instance, a horse may have a low-grade concussive distal limb lameness evident when lunged on the hard surface. However, the primary problem may be proximal suspensory desmitis (PSD), pain from which is evident only when the horse is lunged on a soft surface. Notwithstanding the value of evaluating all the lameness problems present, many of these horses have numerous, low-grade sites of pathological conditions to which they have adapted. Evaluating these can be a frustrating business, and it is important to determine the current problem noticed by a knowledgeable owner or rider. Event horses are often remarkably tolerant of low-grade pain to which they become accommodated compared with dressage horses. Evaluation of the horse while the horse is being ridden can be more difficult, but this form of movement can exacerbate low-grade lameness. Riding may be the only way of observing problems evident during certain movements, such as lack of hindlimb impulsion during a change of gait or when jumping. Seeing the horse ridden by a different, preferably more experienced rider can be helpful in some horses suspected of having back pain or when schooling or behavioral problems are present.

Determining the normal range of soundness is a difficult and contentious issue. Because of age and level of work, most top-level event horses have some degree of orthopedic pathological condition. I prefer to score lameness on a scale of 0 to 10, with 0 being sound and 10 being non–weight bearing. An advanced horse should be sound in the forelimbs when trotted in a straight line, but a large proportion demonstrate a 1 of 10 bilateral forelimb lameness when trotted in a circle on a hard surface. Some horses that are competing satisfactorily may show a greater degree of symmetrical lameness, but asymmetry in lameness may indicate that an important problem exists. Advanced horses can demonstrate up to a 2 of 10 hindlimb lameness when trotted in a straight line, without being penalized for this in a trot-up at a Three Day Event. Many have a 2 to 3 of 10 bilateral hindlimb lameness while circling on a hard surface. Hindlimb lameness evident on soft surfaces is likely to produce lower dressage scores, because the horse will exhibit poor and asymmetrical action.

Flexion tests are useful to exacerbate any subtle lameness problems, but these tests are not specific. Flexion tests can be particularly helpful in evaluating horses with lameness evident only immediately after they have completed an event. These horses can be frustrating, because they are often clinically sound when evaluated subsequently. A persistent positive response to flexion that can be alleviated by diagnostic analgesic techniques is important. Limb protraction, retraction, adduction, and abduction can be helpful in exacerbating upper-limb pain. Turning the horse in a tight circle can be used to assess coordination and flexibility. The range of cervical movement is assessed by observing the horse reach for food (voluntary movement) and by manual manipulation (forced movement). Many horses can cheat and reach the flank by rotation of the upper cervical region, rather than by full lateral flexion of the entire neck.

Different considerations apply when examining the horse with a history of an acute, severe lameness, usually after the cross-country phase of a competition. A comprehensive evaluation of an acutely lame horse must be performed (see Chapter 13) and is described in detail elsewhere.³ Unfortunately, localizing signs may be minimal, the horse may be in cardiovascular shock, and initial efforts must be directed at providing support to the horse and the suspected region of injury. Fractures are caused most commonly by external trauma. Particular attention should be paid to the shoulder region for signs of fracture of the supraglenoid tubercle of the scapula and to the stifle for effusion or periarticular swelling associated with patellar or other fractures. Soft tissue injuries such as severe suspensory desmitis or superficial digital flexor (SDF) tendonitis may cause acute, severe lameness.