Behavioral observations and comparisons of nonlame horses and lame horses before and after resolution of lameness by diagnostic analgesia

Differentiation between alteration in behavior which is the result of pain and that reflecting other behavior is potentially challenging in ridden horses. A ridden horse ethogram has been developed, tested, and combined with a pain score. Nonlame horses generally had lower pain scores than lame horses, although there was a small overlap. To determine if the ethogram could be used to differentiate lame horses before and after diagnostic analgesia had substantially improved lameness, and to verify its use in comparison of nonlame and lame horses, a retrospective study was done. Video recordings of 10 lame horses were reviewed by a trained assessor before and after diagnostic analgesia resolved the baseline lameness and improved any gait abnormalities seen in canter. The ridden horse ethogram was applied to each horse under each circumstance that it was ridden. Occurrence (yes/no) for each of 24 behaviors was recorded. Data were combined with that of an additional 13 nonlame horses and 24 lame horses. After abolition of lameness, the total sum score of behaviors (P < 0.01), sum of facial (P < 0.05), sum of body (P < 0.05), and sum of gait (P < 0.05) scores were all significantly reduced. Fifteen behavioral markers occurred significantly more often in lame horses (P values 0.00-0.05), and an additional 4 markers were only seen in lame horses. For pooled data, all sum markers were significantly higher in lame horses compared with nonlame horses or after resolution of lameness (P < 0.05). The length of the video recordings was not standardized among horses, nor before and after diagnostic analgesia. It was not possible to hide the presence of lameness which could have biased the assessor. Application of the ridden horse ethogram was able to differentiate between lame horses before and after diagnostic analgesia and nonlame and lame horses, although there was some overlap.