5.3 Multifactorial Suppression of Lameness
A horse may not want to favor one limb if it exacerbates a problem (such as pain) in a compensating limb. In this case, the horse may be unable to underload a sore right hind limb without overloading a sore left front limb.
VL 5c Scan/Click to view video. www.getsound.com/tutorials/5c
Axial Lameness
Axial structures are those situated along or near the horse’s midline or centerline. They include the head, neck, chest, back, and rump. Due to their proximity to the horse’s centerline, asymmetric movement between right and left axial anatomy may be difficult to discern for the observer. This is because disparities in movement become harder to detect as we assess analogous structures that reside closer to one another (fig. 5.4 and see VL 5d). Dissimilarities are much easier to see when they are associated with structures farther away from the midline, toward the periphery of the horse.
5.4 Axial Suppression of Lameness
The farther away a structure is from the centerline of the horse’s body, the easier it is to discern a difference in movement between it and its contralateral counterpart. By contrast, it is more difficult to detect asymmetric movement between contralateral structures located closer to the horse’s midline.
VL 5d Scan/Click to view video. www.getsound.com/tutorials/5d
In general, the closer that contralateral counterparts are from one another, the more difficult it is to discern asymmetric movement between the two. Consider the manner in which a seesaw displays movement, for example. It is relatively easy to visually appreciate that the ends of the board are moving dissimilarly from one another: one rises as the other lowers. Of course, reciprocal movement is also occurring along portions of the board located near its pivot point at the center of the seesaw. Yet, motion along this area is considerably more challenging to perceive with our eyes.
To further convolute our frustration, horses often respond to back and neck pain by evading movement along the affected area(s) rather than altering it. And as you might imagine, it is nearly impossible for most horses to brace one side of the neck or back without significantly limiting movement of the other side. The understated discrepancy in movement between corresponding axial structures coupled with their mitigated activity (as the horse attempts to avoid pain) can make proper assessment of the median anatomy very challenging for the observer. Even the most seasoned equine performance professionals will usually choose to pursue hands-on palpation, physical manipulation, and diagnostic imaging to supplement their visual impressions and build confidence in their assessment.
We should always remember that our lame horses are “talking” to us. They’re using a form of “sign language” that is expressed through altered movement. Similar to the way people use gestures to illuminate conversation, horses use them to illustrate what they are experiencing as they move. As effective observers, it is imperative that we learn to listen with our eyes instead of our ears.
Horses suppressing axial pain that exists independent of any limb deficits will often exhibit general stiffness, resistance and/or poor behavior rather than overt lameness (VL 5e). In many instances, a problem is “felt” by the rider rather than seen by a spectator. On the other hand, the size and configuration of the horse’s axial anatomy does lend itself to fairly clear expression of inappropriate position, orientation, and carriage. These visible aberrations are characterized in chapter 23 (p. 161).
VL 5e Scan/Click to view video. www.getsound.com/tutorials/5e
Moreover, we have ways of exposing most forms of “hidden” lameness to facilitate our assessment. The principle function of the lameness examination, for instance, is to create a setting intended to increase the horse’s asymmetric or irregular movement, thereby allowing the observer to more easily detect the presence of one or more problems. Environmental manipulation strategies are discussed in chapter 26 (p. 183).
6 The Issue of Visual Subjectivity Among Observers
The issue of visual subjectivity has become a hot topic in the field of equine-performance medicine. Despite our attempts to “standardize” lameness assessment (via the use of various grading systems), research suggests that veterinarians do not always agree on the location or severity of lameness based on visual impression alone.7,8 This is primarily why advanced diagnostic imaging techniques and motion-sensing devices have become more popular in recent years.
None of us will observe lameness in exactly the same way, just as none of us views artwork identically. Even so, a wealth of information is both visibly expressed by the lame horse and available to the acute observer. Forfeiting this vital information solely based on our inability to agree with one another is a mistake, in my opinion.
Despite having different strategies for building a jigsaw puzzle, for example, multiple individuals within a group still have a good chance of successfully completing the project. Each may have their own set of self-imposed rules and strategies, which may or may not parallel those of other individuals. For instance, some might start by separating the edges from the inside pieces, finding it is easier to work from the outside inward. Grouping pieces of similar design and color may also help to facilitate completion of certain portions. Others will make use of the picture on the box as a guide. Many of us sort pieces by appearance, whereas another group might use the shape of the pieces to determine their location. Although the knowledge of general puzzle-building concepts would be helpful to all of the individuals, all will find the specific method that works best for them. And in the end, everyone completes the same puzzle successfully.
It is important to realize that multiple observers formulating a multitude of visual impressions still have the ability to reach common conclusions when it comes to the location, degree, and nature of a horse’s lameness. Our visual perceptions, if carefully codified, can only facilitate and accelerate the process of accurate diagnosis.
In summary, don’t worry if you don’t see what others see. It is not important that we all agree on what we perceive, but rather that we reach similar conclusions. Use your own “built-in” detection hardware to find the alterations in movement that will steer you in the right direction. The important thing is that we glean as much as possible from the visual exam before moving forward.
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