Objektiv utvärdering av hälta under ryttare

Abstract: Background: The most common reason for veterinary care in horses is lameness. Lameness in riding horses is often difficult to evaluate and in many cases may require riding to come to a diagnosis. . Evaluation of lameness has proven to be very subjective and depends on the examiner. There is a need to evaluate ridden horses in an objective way. Knowledge is limited in this area. Earlier studies have shown that it is difficult to predict how lameness changes when the horse is ridden. Recently, a system to objectively detect lameness has been developed. This system, called “Lameness Locator”, is based on a combined accelerometer- and gyroscope- technique. This technique analyzes asymmetric movements of the pelvis and the head and correlates them to stance phase. The system is validated for induced and clinical lameness while trotting on a treadmill or along a straight-away. The system has not been validated in the ridden horse.Purpose: To evaluate the Lameness Locator with rider on horses with induced lameness.Procedure: Lameness was induced in eight horses by pressure to the sole of the hoof. The pressure was caused by a screw in the toe of a specialized shoe. Lameness was induced either in a forelimb or a hind limb. The horses were measured with the Lameness Locator before and after induction of lameness and with or without a rider. The results from horses, before induced lameness with rider, were compared to the results in lame horses with rider. The results of horses with induced lameness with and without rider were also compared. Comparisons were made using Students t-test and the correlation coefficient was calculated for lameness with and without rider.Results and Discussion: There were significant differences between the groups in all four limbs when lameness was induced. This demonstrates that the system can detect the induced lameness when the horses were ridden. A1/A2 ratios of 0,41- 2,83 were measured (significant level for lameness is 0,5) for forelimbs. A1/A2 ratios of 0,27- 0,86 were registered for hind limbs (significant level of lameness is 0,17). These intervals are a significant change compared to the horses before lameness was induced. Lameness Locator detects normal compensatory changes in the other legs for both front and hind limb lameness. There was a significant difference, in A1/A2 ratio, for forelimb lameness between ridden and unridden horses. The correlation coefficient for forelimb lameness with and without rider was 0,66. This can probably be explained by a slight, though not intended, interference by the rider on the head and neck of the horse. Hind limb lameness with and without rider had a correlation coefficient of 0,97. In both front and hind limb lameness the magnitude of the intervals of measured lameness was lower for horses with rider than horses without. This can be a problem because a rider potentially can disguise lameness.