Equine Lameness for the Layman. G. Robert Grisel, DVM
swiftly. Competence at differentiating problems that pose performance-limiting risk from those that do not is extremely valuable to equestrians at all levels.
2 The Responsibility of the Veterinarian in Successful Management of Equine Lameness
Thirty years ago, visual examination was the primary tool that veterinarians employed to evaluate lame horses. Back then I was fortunate enough to work under the tutelage of legendary veterinarians like Ted Stashak (Colorado State University) and Marvin Beeman (Little Large Animal Clinic), who would extract vast amounts of information during their clinical lameness examinations. Through meticulous inspection and a methodical approach, these practitioners would formulate a visual impression of the horse’s movement for the purpose of discerning clinical significance(s). The ability to “decode” individual gait characteristics enabled them to more quickly and accurately diagnose problems. Exceptional clinicians like Drs. Stashak and Beeman (affectionately referred to as “leg men”) realized that horses with similar pathology would display consistent patterns of abnormal movement (or gait deficits). This approach to evaluation was more representative of “art” than medicine, but often allowed the practitioner to accurately interpret the relationship between certain physical gestures and probable sources of lameness.
Nowadays, veterinarians don’t rely nearly as much on visual examination during their diagnostic workup of the lame horse. This is largely attributed to recent advancements in diagnostic imaging and inertia (motion) sensing. A variety of supplemental tools (also known as “toys”) allow today’s veterinarian to reach a diagnosis with more confidence and less subjectivity.
Unfortunately, the improved technology also tempts today’s veterinarian to spend less time and energy on visual examination and more time retrieving electronic data from a machine. Although we gain valuable information via the use of advanced diagnostic modalities, we can also sacrifice time and direction by compromising the visual aspect of the clinical evaluation.
We rely on the veterinarian to accurately diagnose and treat lameness. Equine veterinarians can do both the horse and the horse owner a further service by getting involved in the recognition phase of lameness management. Through the use of regular telemedical evaluation (remote video analysis)3,4, the veterinarian can help the owner avoid allowing subtle issues to go unchecked.
This strategy can also facilitate post-treatment management of lame horses by providing the veterinarian with regular “virtual views” of their patients in motion. Adjustments to the treatment strategy can be made as necessary depending on updated visual impression(s). Of course, this tool becomes more valuable as the veterinarian’s ability to scrutinize footage continues to improve.
The clinical examination, although subjective, is still the most important diagnostic modality available because the information gathered during this portion of the evaluation tells the veterinarian where to look. And a veterinarian who knows where to look for the problem is more likely to find it.
SECTION II
What Is Lameness?
Lameness in the horse has been around for as long as the horse has been around. Before horses were domesticated, lameness became a factor when it precluded animals from keeping up with the herd or avoiding predation.
Nowadays lameness is, if nothing else, the most common reason why horses are unable to perform their job.5 This form of debilitation is much less of a hindrance to humans who have devised ways to survive by doing things that involve very little (if any) physical exertion (such as writing a book). Every modern horse, on the other hand, is a bona fide athlete. In order to perform its job properly, the equine athlete must be physically comfortable and sound. This is true for racehorses as well as trail horses. Even the retired horse has to ambulate comfortably. This concept becomes clearer as we begin to compare the careers of average horses with those of professional human athletes.
3 The Definition of Lameness
Lameness can be defined as any alteration of the horse’s normal gait. A lame horse alters the way it moves to avoid torsion around painful joint(s) and to center ground reaction forces. A bruised foot, for example, will prompt the horse to change the way it moves its head, body, and limbs. These changes reflect the horse’s attempt to adjust the location and intensity of peak vertical forces experienced by the affected limb. This sounds logical, but what does this mean from a visual standpoint?
Perhaps it would be easier to start by defining soundness. For the purpose of this book, we will define soundness as regular and symmetric movement of the horse (VL 3a). Lameness, therefore, could be counter-described as irregular or asymmetric movement. Any visible difference in movement between the horse’s right and left sides would signify lameness. We generally think of lameness involving the limbs, but horses exhibiting irregular movement of the head, neck, or body (which comprise the median anatomy) would also be labeled as unsound based on this interpretation (VL 3b).
VL 3a Scan/Click to view video. www.getsound.com/tutorials/3a
VL 3b Scan/Click to view video. www.getsound.com/tutorials/3b
The lame horse alters its gait to avoid pain, accommodate some biomechanical restriction in movement, and/or maintain balance.
Depending on the degree of asymmetric movement, lameness might be easier or more difficult to discern with the naked eye. Veterinary studies suggest that, on average, the human eye requires approximately 25% asymmetry in movement in order to detect lameness.6 As we’ll learn, however, knowing where to look, when to look, and what to look for can dramatically enhance our ability to detect even slight variations in movement.
The reality is that every horse is probably lame to some degree; only those displaying enough abnormality to be perceived by the observer’s eye will receive further attention. Put more simply, our ability to distinguish abnormal movement from normal movement is primarily what separates unsound horses from sound horses, respectively.
4 The Art of Seeing Lameness
Foremost, we should consider the basic rationale behind why horses limp. Is it pain? Is it some biomechanical restriction that prohibits normal movement? Pain might be an inciter in some instances, but the uncomfortable horse actually limps in an attempt to avoid pain. The resulting gait abnormality, therefore, is a voluntary action executed by the horse to circumvent the problem as opposed to an involuntary product of the problem. This is an important distinction, because as observers we don’t directly appreciate the source of the horse’s pain. Rather, we see how the horse alters its movement to escape it.
Visual assessment of the horse’s physical adjustments relies on the art of pattern recognition, which is relatively simple once we know where to look, when to look and what to look for. This concept is familiar to us, because all of us practice pattern recognition in one form or another in our daily activities/jobs. Horse trainers, for instance, regularly evaluate recurring patterns of body language expressed by riders, both correct and incorrect. Farriers, on the other