Effect of lungeing on head and pelvic movement asymmetry in horses with induced lameness

Abstract

Lungeing is an important part of lameness examinations, since the circular path enforced during lungeing is thought to accentuate low grade lameness. However, during lungeing the movement of sound horses becomes naturally asymmetric, which may mimic lameness. Also, compensatory movements in the opposite half of the body may mimic lameness. The aim of this study was to objectively study the presence of circle-dependent and compensatory movement asymmetries in horses with induced lameness. Ten horses were trotted in a straight line and lunged in both directions on a hard surface. Lameness was induced (reversible hoof pressure) in each limb, one at a time, in random order. Vertical head and pelvic movements were measured with body-mounted, uni-axial accelerometers. Differences between maximum and minimum height observed during/after left and right stance phases for the head (HDmax, HDmin) and pelvis (PDmax, PDmin) were measured. Mixed models were constructed to study the effect of lungeing direction and induction, and to quantify secondary compensatory asymmetry mechanisms in the forelimbs and hind limbs. Head and pelvic movement symmetries were affected by lungeing. Minimum pelvic height difference (PDmin) changed markedly, increasing significantly during lungeing, giving the impression of inner hind limb lameness. Primary hind limb lameness induced compensatory head movement, which mimicked an ipsilateral forelimb lameness of almost equal magnitude to the primary hind limb lameness. This could contribute to difficulty in correctly detecting hind limb lameness. Induced forelimb lameness caused both a compensatory contralateral (change in PDmax) and an ipsilateral (change in PDmin) hind limb asymmetry, potentially mimicking hind limb lameness, but of smaller magnitude. Both circle-dependent and compensatory movement mechanisms must be taken into account when evaluating lameness.

Head and pelvic movement asymmetries at trot in riding horses in training and perceived as free from lameness by the owner

“…For the horses with induced hind limb lameness [23] the mean PDmin left/right values were -9.0/6.2 mm and this degree is in accordance with six clinically hind limb lame horses investigated by Maliye et al, [28] with a group-mean value for PDmin of 6.0 mm (absolute value). The mean values for PDmin left/right (-5.5/5.8 mm) were slightly lower in the present study but the 25 th percentile (-8.7) and 75 th percentile (7.2) exceeded these values.…”

“…In a previous study of ten horses with induced forelimb lameness [23], the mean degree of asymmetry for HDmin left/right was -26.1/20.1 mm. The 5 th and 95 th percentiles of the present study exceed these values, presented in Table 1, but the mean values were lower (HDmin left/right -15.8/12.8 mm).…”

“…Therefore early, precise and accurate recognition of lameness with biomechanical methods has been the focus of research in recent decades. In trot, the non-lame horse shows a symmetric sinusoidal motion pattern of head and pelvis which undergoes systematic changes when loading of the limbs changes, for example as a result of lameness [8–10]. The differences in maximum and minimum position of head or pelvis between left/right stances (HDmin, HDmax, PDmin and PDmax) are examples of symmetry measures commonly used for quantification of lameness and are directly linked to the underlying changes in limb loading and propulsion [10,11].…”

“…However lungeing is commonly used during lameness and pre-purchase evaluations since it induces differences in the severity of apparent lameness compared to trot on the straight [22]. Lungeing also affects the symmetry of the motion pattern in sound horses [23,24] and this circle-dependent asymmetry will be superimposed on the pre-existing lameness of the horse making it more, or less, visible [23]. Whether this circle-dependent asymmetry will increase or decrease the degree of asymmetry depends on whether the limb contributing to the asymmetry is on the inside or outside of the circle [23].…”

“…Lungeing also affects the symmetry of the motion pattern in sound horses [23,24] and this circle-dependent asymmetry will be superimposed on the pre-existing lameness of the horse making it more, or less, visible [23]. Whether this circle-dependent asymmetry will increase or decrease the degree of asymmetry depends on whether the limb contributing to the asymmetry is on the inside or outside of the circle [23]. This phenomenon is very relevant for diagnostic procedures in clinical cases but has not yet been investigated thoroughly.…”