Poor Performance and Lameness

Chapter 97Poor Performance and Lameness



Sue J. Dyson


Horses may be presented to a veterinarian because of a change in performance or behavior or failure to live up to the expected level of performance, rather than because the rider or trainer has recognized overt lameness. Many of these horses do have musculoskeletal problems. The type of complaint often reflects the discipline in which the horse is used. For example, an event horse may be assessed because it has started stopping at drop fences, whereas a dressage horse may be evaluated because it takes uneven steps behind in passage or piaffe.



Challenge of Assessment


This type of horse presents the veterinarian with a diagnostic challenge that may involve assessment not only of the horse, but also of the horse and rider together and the rider’s ability. Such an assessment requires knowledge of the sport in question and an ability to recognize when the problem is a lack of athletic ability or a mental problem rather than a pain-related musculoskeletal disorder or some other pathological condition, such as an upper airway disorder. The assessment also requires good knowledge and appreciation of how horses normally move and the variations among different breeds and types and an ability to recognize subtle changes in gait, such as a slightly reduced lift to the stride or stiffness in movement of the back. The assessment requires basic knowledge of equine locomotion and how gait may be modified by pain and also requires the ability to recognize when a rider may actually be creating the problem. Training methods and style of riding may contribute to the development of lameness.


This section sets out to discuss some of the different problems that may be encountered and the types of conditions that may be the cause of poor performance and to suggest some methods of approach to diagnosis. These may vary to some extent depending on whether the clinician is dealing with a competent professional rider or trainer or an inexperienced or even experienced amateur who lacks ability.



History


It is essential to obtain a comprehensive history to determine whether the horse has genuinely performed better previously at this level of competition, or moved better, and precisely what changes have been observed. It is important to listen carefully to the owner to properly understand the perceived problem, however small it might be. This is particularly important if the clinician does not have prior knowledge of the horse.


Determine the answer to the following questions:


1 What are the age and training history of the horse?

2 Does the horse have the musculoskeletal coordination and strength to do what is being asked?

3 Has the horse recently moved up a level of competition? Does the horse have the confidence or athletic ability to cope?

4 What is the current work program? How does this vary from day to day? Is the horse allowed turnout?

5 Has a recent change in the work pattern or intensity or some other change in management occurred?

6 Has the bit been changed?

7 Did the horse sustain a fall or any other trauma before the onset of the problem?

8 Has a recent change in the rider or trainer occurred?

9 Has an alternative rider been tried?

10 Has the horse ever exhibited clinical signs consistent with exertional rhabdomyolysis?

11 Under what circumstances is the problem apparent?

Viewing videos of the horse when it was performing normally sometimes can be helpful to compare with the findings of your own clinical evaluation. If the horse has recently changed ownership, comparing video recordings of the horse ridden by the previous rider and by the current rider can be useful to determine whether a change in riding style or training techniques may be responsible for making a previously subclinical problem become symptomatic, or to determine if the problem could be related directly to the manner in which the horse is being worked.


The types of clinical problems that may be encountered are listed in Box 97-1.



BOX 97-1 Types of Clinical Problems



• Not jumping as well: knocking down rails. This may be pain related or may be caused by the rider presenting the horse poorly to the fence.

• Not jumping as well: stopping. This may be a horse or rider confidence or ability problem, or may be pain related.

• Not making distances in combination fences. This may occur because the horse is landing too steeply, saving one or both front feet and therefore having too much ground to make up, or through lack of push from behind, reflecting a hindlimb lameness. Alternatively, if the horse is presented poorly to the first element of the fence, the subsequent elements become increasingly difficult.

• Reluctance to land leading on a specific leg. This can reflect a forelimb or less commonly a hindlimb lameness. Peak ground reaction forces at landing are significantly greater in the trailing forelimb than in the leading forelimb1; therefore a tendency to land with the right forelimb leading is most likely a reflection of right forelimb pain. However, stress on the suspensory apparatus is greater in the leading forelimb; therefore in association with suspensory pathology a horse may avoid landing with the affected limb leading.

• Napping (resistance) on the approach to a fence off a turn. Nappiness may be pain related or behavioral.

• Not jumping straight (e.g., jumping to the right), with a tendency for the hindlimbs to drift toward the direction in which the horse is jumping (to the right). This usually reflects pain or weakness in the ipsilateral hindlimb of the side to which the horse is jumping. Less commonly the problem may be caused by reluctance to land on the contralateral forelimb (e.g., the left).

• Loss of hindlimb power. This may be caused by back pain or hindlimb lameness. Less commonly it may be the result of low-grade hindlimb ataxia.

• Change in the shape the horse makes over a fence—for example, loss of bascule (jumping with a rounded arc over a fence). This may reflect back pain or forelimb or hindlimb lameness, or possibly gastric ulceration. It may also reflect the way in which the horse is presented to the fence.

• Rushing fences. This can be the way an excitable horse always jumps, but if the horse used to jump normally, rushing the fence usually reflects a painful problem. However, if the horse has been stopping for whatever reason and has been chased to the fences, it will inevitably rush. If a horse is overly restricted by the rider’s hands it may also try to rush to escape.

• Loss of action. This can reflect the way in which the horse has been ridden and trained. Some loose, free-moving young dressage horses become much more restricted in their stride when ridden exercise is commenced. An apprehensive rider may restrict a potentially exuberant horse. A bored horse, particularly with a Warmblood mentality, may just switch off and refuse to go forward freely and loosely. Loss of action also may reflect forelimb or hindlimb lameness or back pain.

• Stiffness. Stiffness should be evaluated carefully to differentiate loss of action and back stiffness from restriction of gait caused by a bilateral forelimb or hindlimb lameness.

• Inability to perform medium or extended trot. Unless a horse is properly balanced with adequate hindlimb impulsion, it cannot perform medium or extended trot. Horses vary considerably in the ability to collect and extend. In general the Thoroughbred breed has much less natural ability than many of the Warmblood breeds. Some horses have to learn how to perform a medium and an extended trot and must first develop sufficient muscular coordination and power before they are able to do so. However, if a horse was previously able to work in medium and extended paces and now cannot do so, or if the rhythm becomes irregular, this can reflect forelimb or hindlimb lameness or back pain.

• Inadequate hindlimb impulsion in trot, with a tendency to break to canter if asked to work harder. This usually reflects hindlimb lameness.

• Difficulty in performing specific dressage movements—for example, right half pass. This often reflects a back or sacroiliac joint region problem or hindlimb lameness.

• Tendency to become disunited behind in canter. This usually reflects hindlimb lameness. However, it is important to recognize that young horses can find maintaining true canter difficult, sometimes just in one direction, or sometimes in both directions. This often can be overcome by training and development of muscular strength and coordination. Some trained horses that canter true when ridden may become disunited when cantering on the lunge. Hindlimb lameness may predispose to a horse becoming disunited. If the problem occurs to a similar extent on both reins, it often reflects a bilateral problem, but if it occurs on only one rein, the problem is more likely to be unilateral.

Although the canter stride is initiated by the trailing hindlimb, which bears weight alone, the stance time, peak vertical ground reaction forces, and range of motion of the proximal limb joints are higher in the leading hindlimb.2,3 Therefore if the horse consistently becomes disunited on the left rein, this is likely to reflect discomfort in the leading left hindlimb.


• Late flying changes, or difficulty in changing from right to left or from left to right. This usually results from hindlimb lameness.

• Inability to maintain a consistent rhythm in piaffe, passage, or canter pirouettes. This usually reflects a hindlimb lameness.

• Unlevelness in certain movements. Mild irregularities in rhythm may be detectable only in certain movements—for example, left half pass and right shoulder in. Such irregularities can reflect forelimb or hindlimb lameness or may be induced by the rider overrestricting with the hand and not creating sufficient hindlimb impulsion. Dressage riders often refer to bridle lameness, implying that lameness is not true because it cannot be detected when the horse is trotted in hand or lunged. This usually is a misnomer, because most bridle- or rein-lame horses have a genuine lameness, which may be apparent only when the horse is ridden.

• Crookedness, or reluctance to take the bit evenly on the rider’s left and right hands. This can result from a training problem or can be caused by lameness or unwillingness to accept the bit because of oral pain. Less commonly it may reflect temporomandibular joint pain.

Related posts:

  1. Lameness in Horses: Basic Facts Before Starting
  2. Thermography: Use in Equine Lameness
  3. Counterirritation
  4. The Carpal Canal and Carpal Synovial Sheath

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Jun 4, 2016 | Posted by in EQUINE MEDICINE | Comments Off on Poor Performance and Lameness

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