Clinical TechniquesLong Toes in the Hind Feet and Pain in the Gluteal Region: An Observational Study of 77 Horses
Introduction
This article addresses an observation we have made that horses with long toes in the hind feet often show a pain response on palpation of the gluteal region. The riders or trainers of these horses often report performance problems that are related to bad behavior, resistance to the rider, lack of impulsion, or a stiff or irregular gait. Typically, the horse’s gait and performance are improved with the trimming and shoeing strategy discussed in this article, which includes moving the breakover point back at the toe. However, what we had not yet ascertained was whether the gluteal pain also abated with this approach of hoof care, and thus was related to toe length in the hind feet.
In addition to long toes, the hind feet in these horses typically have low heels and lack adequate mass in the frog and digital cushion, in some cases having crushed, underslung, or collapsed heels. On lateral radiographs of these feet, the solar or plantar angle of the third phalanx (P3) in relation to the ground usually is zero or even negative (ie, the wings of P3 are level with or lower than the tip).
The hindlimb stance in these horses is one in which the load-bearing surface of the hoof appears to be too far forward in relation to the coronary band and to the fetlock and cannon (Fig. 1). These horses tend to “stand under themselves” with their hind feet, meaning that at rest the foot is placed further forward than normal in relation to the vertical axis of the limb and the main mass of the hindquarter, giving the horse a “sickle-hocked” appearance (Fig. 2). This stance may provide a clue to the reason why many of these horses show a pain response on palpation of the gluteal region and why many are performing below the expectations of their owner and/or trainer.
Myers used a railway metaphor to describe the complex biomechanics of the human musculoskeletal system and show how anatomical connections act as functional continuities.1 Adapting that approach to the equine body, one can track “lines of pull” through the various connective tissues and muscles all the way from the hind P3 up into the pelvic region and forward into the trunk (Fig. 3). According to this approach, a problem in any one of the functionally related structures between digit and head can affect that entire myofascial line, its counteracting line(s), and therefore posture and movement. One would also expect a pain response on palpation of areas under excessive tension or contracture.1 With this concept in mind, it becomes easier to understand how the long toe, low heel, forward stance described previously and shown in Figure 2 could cause excessive tension and palpable pain in the gluteal region.
The aim of our study was simply to document this relationship between long toes and gluteal pain in a group of client-owned horses, and to show the remedial value of shortening the toe. Because “long toe” is a subjective visual assessment, we used an objective measurement (breakover distance or BD) taken from a lateral radiograph of each hind foot to document toe length in each horse. Our hypotheses were as follows: (1) BD in the hind feet is greater in horses with palpable gluteal pain than in those without gluteal pain, and (2) trimming and shoeing (or trimming alone in barefoot horses) to shorten the BD alleviates the pain in horses with gluteal pain.
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Subjects and Study Design
In the course of this observational study, we evaluated a total of 77 client-owned horses that were presented to our Equine Podiatry and Rehabilitation Service or examined on the farm by a member of our team, between April 2006 and December 2007. To be included in the study, the horse had to have a minimum of one set of lateral radiographs of the hind feet and recorded results of gluteal palpation performed on the same day. All horses, except 10, were studied retrospectively. The remaining 10
Study 1
Of the 67 horses in this study group, 50 horses (75%) were positive on gluteal palpation and 17 horses (25%) were negative. The mean BD in the positive horses was 24.2 ± 1.3 mm (range, 5–43.5 mm; Fig. 8). The mean BD in the negative horses was 18.8 ± 2.0 mm (range, 5–33 mm). Although small, the difference in mean BD between positive and negative horses was statistically significant (P = .04).
The 24 horses with gluteal pain that were subsequently reevaluated had a mean BD of 25.6 ± 2.1 mm
Discussion
The aims of our study were met because we showed a statistically significant relationship between long hind toes and gluteal pain and also the remedial value of shortening the BD. One could argue that a difference in mean BD of only 5 mm or so between the positive and negative horses in study 1 is too small to be clinically relevant. Furthermore, there was a good deal of overlap in individual BD between positive and negative horses. However, as Figure 9 graphically illustrates, there was a
Acknowledgments
The authors acknowledge the editorial input of Christine King, BVSc, MACVSc, MVetClinStud, and also partial funding from the Merck-Merial Summer Research Internship Program and the NCVMF Gallop of Honor Podiatry Fund.
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