SPORTS MEDICINE, LAMENESS, AND REHABILITATION


musculoskeletal pain.16 Forty horses were ridden by the normal rider of each horse and a single skilled pro- fessional rider in randomorder, performing a standar- dized dressage-type test of 8.5 minutes’ duration. Rider skill altered gait quality, with overall higher gait quality scores for the professional rider. The pro- fessional rider had a variable influence on the pres- ence or absence of lameness and gait abnormalities in canter. However, there was no significant difference in the mean RHpE scores when ridden by the normal rider compared with the professional rider, although thereweresomedifferences in thebehaviors exhibited by the horses. Studies in Denmark, Sweden, Switzerland, and the


applied the RHpE to 20 horses in real time or by assessment of video recordings.15 Nontrained observ- ers (n=10) of different professional backgrounds were able to differentiate between nonlame and lame horses based on application of the RHpE to video recordings.12 Equine veterinarians (n=10) of variable experience were, after preliminary video-based train- ing, able to differentiate between horses with low- grade lameness and nonlame horses assessed in real time using the RHpE.15 When comparing the 10 equine veterinarians and an experienced observer, there was also excellent consistency in overall agree- ment for total RHpE scores among raters (intraclass correlation coefficient = 0.97, p<0.001), and for exact agreement between individual observers, there was good to moderate agreement (intraclass correlation coefficient = 0.7, p<0.001). Rider skill cannot mask the behavioral signs of


United Kingdom have shown that at least 50% of the sports horse and leisure horse populations show lame- ness 6 abnormalities of canter, especially when rid- den.17–20 The welfare of sports horses is under increasing scrutiny as the social license to compete with horses is debated widely.21–25 Several studies have investigated the relationship between RHpE scores and the performance of sports horses.26–30 The aim of this review is to summarize these studies and to comment on their clinical relevance to the sports horse veterinary practitioner, who is the ultimate guardian of sports horse welfare.


2. 5-Star 3-Day Events


Pilot data were acquired at the Burghley Concours Complet Internationale (CCI) 4-star (now 5-star) event in 2018.26 A convenience sample of 35 horses, compet- ing in consecutive order on the second day of dressage, were each assessed for a minimum of 10minutes dur- ing trot and canter in the late stages of warm-up. The RHpE was applied by a trained observer. Cross-coun- try performance was obtained from the competition website; horses were classified as completing, elimi- nated, or retired. The median RHpE score for 27 non- lame horses was 2/24 (interquartile range [IQR] = 0–3; range = 0–4). The median RHpE score for 8 horses with gait abnormalities (lameness or abnormalities of


318 2022 / Vol. 68 / AAEP PROCEEDINGS


canter) was 7.5/24 (IQR = 4–8; range = 3–9). The RHpE score was ≥ 8/24 in only 4 horses. Thirty-four horses started cross-country, of which 35% were elimi- nated or retired. The proportion of horses failing to complete was significantly higher for those with RHpE scores ≥ 7/24 compared with scores < 7/24. Of 28 horses with an RHpE score < 7/24, 8 (29%) were elimi- nated or retired. Of 6 horses with an RHpE score ≥ 7/24, 4 (67%)were eliminated or retired. The pilot study highlighted that in a cohort of


highly trained event horses competing at 5-star level, it may be useful to use a slightly lower total RHpE score as an indicator of possible influence on perform- ance, rather than the score of ≥ 8/24, previously iden- tified as a reliable score for differentiating sports horses competing at a variety of levels, from unaffili- ated to elite, with and without musculoskeletal pain.8,9,11,12 Additional data were acquired for all starters


(n=137) warming up for the dressage phase of two CCI 5-star events (Badminton May 2019, n=70; Burghley September 2019, n=67).27 Episodic, mild (≤ grade 2/8)31 forelimb or hindlimb lameness was observed in 13.1% of starters; 20.4% showed abnormalities of canter, and 6.6% exhibited poor hindlimb engagement and impulsion. RHpE scores ranged from 0 to 9/24. Only 10/137 (7.3%) horses had an RHpE score ≥ 8/24. The median score for horses with neither lameness nor abnormalities of canter was 3/24 (range = 0–9), compared with a median score of 5/24 (range = 1–9) for horses with gait abnormalities. Horses with lameness or abnormalities of canter had a significantly higher RHpE score compared with other horses. There was a moderate correlation between the


RHpE scores for individual horses that competed at both events. The overall frequency of occurrence of each of the behaviors comprising the RHpE is sum- marized in Table 2. There was amoderate positive cor- relation between dressage penalty scores (the mean value for the 3 judges [the Ground Jury]) and the RHpE score. The proportion of horses failing to com- plete the cross-country phase was higher for horses with an RHpE score ≥ 7(n=10/17; 59%) compared to horses with an RHpE score < 7(n=39/117; 33%). There was a strong trend toward a higher RHpE score for horses that did not complete (median = 4) com- pared with those that did complete (median = 3) the cross-country phase. There was a higher RHpE score for horses that retired during the cross-country phase compared with those that completed but no difference between eliminations and retirements. There was no relationship between the RHpE score and total showjumping penalties. There was a signif- icant weak correlation between total RHpE score and final horse placings (n=70). In conclusion, horses with higher RHpE scores had


higher dressage penalties and lower overall finish pla- ces. Combining the data from the pilot study and the main study (n=172), 63% of horses with an RHpE score ≥ 7/24 failed to complete cross-country,


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