Rater agreement of visual lameness assessment in horses during lungeing.
BACKGROUND
Lungeing is an important part of lameness examinations as the circular path may accentuate low-grade lameness. Movement asymmetries related to the circular path, to compensatory movements and to pain make the lameness evaluation complex. Scientific studies have shown high inter-rater variation when assessing lameness during straight line movement.


OBJECTIVE
The aim was to estimate inter- and intra-rater agreement of equine veterinarians evaluating lameness from videos of sound and lame horses during lungeing and to investigate the influence of veterinarians' experience and the objective degree of movement asymmetry on rater agreement.


METHODS
Cross-sectional observational study.


METHODS
Video recordings and quantitative gait analysis with inertial sensors were performed in 23 riding horses of various breeds. The horses were examined at trot on a straight line and during lungeing on soft or hard surfaces in both directions. One video sequence was recorded per condition and the horses were classified as forelimb lame, hindlimb lame or sound from objective straight line symmetry measurements. Equine veterinarians (n = 86), including 43 with >5 years of orthopaedic experience, participated in a web-based survey and were asked to identify the lamest limb on 60 videos, including 10 repeats. The agreements between (inter-rater) and within (intra-rater) veterinarians were analysed with κ statistics (Fleiss, Cohen).


RESULTS
Inter-rater agreement κ was 0.31 (0.38/0.25 for experienced/less experienced) and higher for forelimb (0.33) than for hindlimb lameness (0.11) or soundness (0.08) evaluation. Median intra-rater agreement κ was 0.57.


CONCLUSIONS
Inter-rater agreement was poor for less experienced raters, and for all raters when evaluating hindlimb lameness. Since identification of the lame limb/limbs is a prerequisite for successful diagnosis, treatment and recovery, the high inter-rater variation when evaluating lameness on the lunge is likely to influence the accuracy and repeatability of lameness examinations and, indirectly, the efficacy of treatment.
Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden.
M
M
Hammarberg
Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden.
A
A
Egenvall
Department of Veterinary Clinical Sciences, The Royal Veterinary College, University of London, Hatfield, UK.
T
http://orcid.org/0000-0002-0702-4289
T
Pfau
Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden.
M
M
Rhodin
D000818:Animals; D001696:Biomechanical Phenomena; D003430:Cross-Sectional Studies; D005260:Female; D006734:Horse Diseases / Q000175:diagnosis*; D006736:Horses; D007794:Lameness, Animal / Q000175:diagnosis*; D008297:Male; D015588:Observer Variation; D018634:Veterinarians
agreement; circle; horse; inter-rater; lameness evaluation; lungeing