Application of the Ridden Horse Pain Ethogram to 150 Horses with Musculoskeletal Pain before and after Diagnostic Anaesthesia

SIMPLE SUMMARY: Riders are often frustrated because when they recognise a decline in their horse’s performance, they seek professional advice and are informed that their horse is not lame based on an examination in hand ± on the lunge. The Ridden Horse Pain Ethogram (RHpE) was developed to facilitate the recognition of musculoskeletal pain in horses. An RHpE score of ≥8/24 reflects the likely presence of musculoskeletal pain. The aim of this study was to document observations made during ridden exercise of 150 horses with a history of poor performance, comparing RHpE scores before and after nerve blocks ± change of saddle. The most frequent lameness grade when ridden was 2/8 (range: 0–4); 35% of the horses had no overt lameness but lacked hindlimb impulsion. The most frequent RHpE score was 9/24 (range: 2–15/24), which declined to 2/24 (range: 0–12) after the interventions and was associated with improved gait quality and rideability. Despite recent professional saddle fit, an ill-fitting saddle contributed to poor performance in 37% of the horses. This study highlights the importance of ridden exercise in the investigation of poor performance/ low-grade lameness and the value of the RHpE to verify the presence of musculoskeletal pain. Nerve blocks are vital to determine the source(s) of pain that compromise performance. ABSTRACT: The Ridden Horse Pain Ethogram (RHpE) was developed to facilitate the recognition of musculoskeletal pain. The aim of this study was to document changes in RHpE scores before and after diagnostic anaesthesia was performed to alleviate pain ± when the saddle was changed. One hundred and fifty horses underwent ridden exercise as part of an investigation of poor performance. The RHpE was applied before and after the interventions. Fifty-two (34.7%) horses exhibited a bilaterally symmetrical short step length and/or restricted hindlimb impulsion and engagement. Fifty-three (35.3%) horses had episodic lameness; only forty-five (30.0%) horses were continuously lame. The median maximum lameness grade when ridden was 2/8 (interquartile range [IQR]: 0–3; range: 0–4). Fifty-six (37.3%) horses had an ill-fitting saddle, which was considered likely to influence performance. The median RHpE scores after the interventions (2/24 [IQR: 1–3, range: 0–12]) were significantly lower than before the interventions (9/24 [IQR: 8–11, range: 2–15]) (Wilcoxon signed-rank z = 10.6, p < 0.001). There was no correlation between the RHpE score and maximum lameness grade before diagnostic anaesthesia (Spearman’s rho = 0.09, p = 0.262). It was concluded that the absence of overt lameness does not preclude primary musculoskeletal pain. Gait quality and performance can be improved by diagnostic anaesthesia, with substantial reductions in RHpE scores.