A SYSTEM FOR IDENTIFYING LAMENESS
The Ridden Horse Pain Ethogram (RHpE) was developed by Sue Dyson, VetMB, PhD, in 2018 to help detect lameness.
If a horse exhibits eight or more of the following 24 behaviors, it is likely that he is experiencing musculoskeletal pain.
1. Repeated changes of head position (up/down), not in rhythm with the trot
2. Head tilted or tilting repeatedly
3. Head “in front of vertical” (more than 30 degrees) for 10 seconds or more
4. Head “behind vertical” (more than 10 degrees) for 10 seconds or more
5. Head position changes regularly, tossed or twisted from side to side, corrected constantly
6. Ears rotated back behind vertical or flat (both or one only) five seconds or more; repeatedly lay flat
7. Eyelids closed or halfclosed for two to five seconds; frequent blinking
8. Sclera (white of the eye) exposed repeatedly
9. Intense stare (glazed expression, “zoned out”) for five seconds or more
10. Mouth opening and/or shutting repeatedly
with separation of teeth, for 10 seconds or more
11. Tongue exposed, protruding or hanging out, and/or moving in and out repeatedly
12. Bit pulled through the mouth on one side (left or right) repeatedly
13. Tail clamped tightly to middle or held to one side
14. Tail swishing in large movements: repeatedly up and down/side to side/circular; repeatedly during transitions
15. A rushed gait (frequency of trot steps great than 40 per 15 seconds); irregular rhythm in trot or canter; repeated changes of speed in trot or canter
16. Gait too slow (frequency of trot steps less than 35 per 15 seconds); passage like trot
17. Hind limbs do not follow tracks of forelimbs
but repeatedly deviate to left or right; on three tracks in trot or canter
18. Repeated lead changes at the canter in front and/or behind; repeated strike off on wrong lead; disunited
19. Spontaneous changes of gait (e.g., breaks from canter to trot, or trot to canter)
20. Stumbles or trips more than once; repeated bilateral hind-limb toe drag
21. Sudden change of direction, against rider’s direction; spooking
22. Reluctance to move forward (has to be kicked and/ or given verbal encouragement); stops spontaneously
23. Rearing (both forelimbs off the ground)
24. Bucking or kicking backwards (one or both hind limbs
surprising, given that many of the behaviors on the RHpE are often dismissed as “normal” by riders. “I’ve lost count of the times that clients have said to me, ‘He’s always found it difficult to canter---that’s normal for him’,” says Dyson. “Or, ‘He’s
The researchers found that 73 percent of the horses in the study that were assumed to be sound by their owners actually had some degree of lameness.
never been a very willing horse ever since I bought him,’ or ‘he always comes out a bit stiff.’”
An even higher proportion (82 percent) of the study’s lesson horses were found to be lame by the researchers, who noted that this group also had the highest median RHpE scores.
“When I think back to my childhood and think of all the horses at my local riding school, where I spent all my spare hours, and how these horses behaved, I don’t think this is a new phenomenon,” says Dyson. “One of the reasons that some of these horses are so safe for beginners is that they don’t want to go quickly; they hold their backs stiffly to compensate for lameness and minimize their discomfort, making them easier to ride. With a bigger range of motion they would be more difficult to ride.”
She adds that a few simple management changes could help keep lesson horses more comfortable: “I’d like see better use of painrelieving medications such as phenylbutazone, and more lessons on a mechanical horse to establish basic position and balance, so that beginner riders are better able to ride bigger-moving, less lame horses,” Dyson says. “And more attention paid to better-fitting saddles for horses and riders. Although not significant in this study, we have done another study ready for publication in which we found that tight tree points can affect the RHpE, as does the rider sitting on the back of the saddle versus the middle of the saddle.”
Overall, any horse who displays eight or more
RHpE behaviors needs a full lameness workup, says Dyson, “although, sadly, non-specialist veterinarians may currently not have the skills to investigate properly.”
Reference: “Application of a Ridden Horse Pain Ethogram and its relationship with gait in a convenience sample of 60 riding horses,” Animals, June 2020