Science

Not opinion.
Peer-reviewed method.

Science-backed  ·  Evidence-based  ·  AI-enabled

Kairon is built on decades of clinical experience and a substantial body of peer-reviewed research centred on the Ridden Horse Pain Ethogram (RHpE), developed by Dr Sue Dyson and colleagues.

2×

A horse showing more than 7 RHpE markers at warm-up is twice as likely not to complete the cross-country.

5* three-day eventing — Dyson & Ellis, 2022

171

Horses in which resolution of musculoskeletal pain through diagnostic anaesthesia consistently reduced RHpE scores — demonstrating causal link.

Dyson & Van Dijk, 2020 — Dyson et al., 2023

96×

Horses with an RHpE score of ≤4 at a PPE were 96x more likely to compete at the same level or higher over the following 4 years.

Dyson — Animals (MDPI), 2026

>1 400

Horses assessed across all Olympic disciplines, from novice to 5* elite level. The correlation between RHpE score and final competition ranking is consistent across all levels.

Dyson & Pollard, 2021–2022 — Dyson & Ellis, 2022

Co-Founder & Chief Scientific Officer

Dr. Sue Dyson

Dr. Sue Dyson
  • Former Head of Clinical Orthopaedics, Centre for Equine Studies, Animal Health Trust, in Newmarket (UK), where she led a world-renowned referral service for lameness and poor performance
  • Author of 460+ scientific publications and internationally recognised authority in equine sports medicine and investigation of poor performance
  • Developer of the Ridden Horse Pain Ethogram (RHpE) together with collaborators, a scientifically validated framework for identifying pain-related behaviours in ridden horses
  • Former 4* eventing rider and British Horse Society Level 5 coach, combining veterinary expertise with decades of hands-on experience in equestrian sport

Dr Dyson, together with a team of collaborators, developed the Ridden Horse Pain Ethogram — a validated clinical tool built from decades of systematic observation. Her work established that ridden horses express pain through specific, measurable, reproducible behaviours that disappear once pain is removed.

This causal link is what makes the RHpE clinically meaningful: it is not just a list of signs associated with discomfort, but a validated measure where each marker has a defined threshold, strict temporal rules and a proven relationship with pain.

Kairon turns the method into something that can be applied at scale, in the field, with the speed and precision that AI enables — while keeping her expertise as the gold standard against which the model is trained.

Discover her approach

The RHpE

24 markers. Strict definitions. Causal proof.

The Ridden Horse Pain Ethogram (RHpE) consists of 24 specific, quantifiable biomechanical and behavioural markers. Each marker is bound by strict definitions and temporal rules. Crucially, most of these markers disappear once the underlying pain is resolved — proving a direct causal link to horse discomfort.

Anatomy of the RHpE

Any horse can display a movement or action in isolation — this alone does not indicate pain. But when such action persists or repeats over time, it becomes a behaviour.

3 Temporal Rules

Timed events

Measured in seconds of occurrence

Repeated events

Measured by number of occurrences

Trot pace

Measured via the number of trot steps over a 15-second segment

5 Focus Areas

  • Ears back
  • Exposed sclera
  • (Half-)closed eyelid
  • Intense stare
  • Mouth opening
  • Bit pulled
  • Tongue
  • Head tilt
  • Head movement side to side
  • Head movement up and down
  • Head >10° behind the vertical
  • Head >30° in front of the vertical
  • Tail swishing
  • Tail position
  • Moving on 3 tracks
  • Stumbling or bilateral hindlimb toe drag
  • Canter dysfunction
  • Unrequested gait change
  • Rushed gait
  • Gait too slow
  • Spooking
  • Bucking
  • Rearing
  • Reluctance to move forward

The Threshold of Pain

Any horse can display a movement or action in isolation — this alone does not indicate pain.

But when such action persists or repeats over time, it becomes a 'behaviour'.

Extensive research by Dr. Sue Dyson and her team has demonstrated that the presence of multiple such behaviours—statistically, 8 or more out of 24—makes the presence of underlying pain or discomfort near certain.

  • Most normal, comfortable horses have an RHpE score of 0-4.
  • A score of 8 or more is associated with the presence of musculoskeletal pain, but a horse may be in pain and displaying fewer than 8 markers.
  • Persistent scores of 6–7 are likely to reflect some level of discomfort.
  • The RHpE should also be used longitudinally: consistently low scores are a positive indicator of ridden comfort and welfare.
See the 24 behaviours

Research timeline

Decades of clinical research, now accessible from your phone.

Before 2018

Clinical foundation

Dr. Sue Dyson spends over three decades studying, diagnosing and treating ridden horses at the Animal Health Trust, in Newmarket. She systematically notices the behavioural signals that correlate with pain under saddle.

2018

Publication of the RHpE

The Ridden Horse Pain Ethogram is formally published — a 24-marker validated tool establishing a causal link between specific ridden behaviours and pain.

The result of a 6-phase study spanning 3 years and 400 horses.

Read the article.

2020s

A New Standard in Equine Medicine

The RHpE becomes a cornerstone of modern equine sports medicine. Backed by a rapidly growing body of peer-reviewed literature:

Performance & Competition: Studies at elite and basic levels definitively link lower ethogram scores to better competition rankings.

Clinical Diagnosis & Health: The RHpE is influenced by axial skeleton pain (neck, back, pelvis), gait abnormalities (for example canter dysfunction, not just overt lameness), ill-fitting tack and equine gastric ulcer syndrome.

Global Education: The method has been officially adopted into several veterinary, physiotherapist, saddle-fitter and equine professional curricula worldwide.

2026

Kairon

Kairon turns three decades of Dr. Dyson's clinical research into a tool accessible by anyone in the world, from their smartphone.

  • Unique database of >100 hours of videos, built from 40+ years of Dr. Dyson's systematic clinical observation
  • AI models trained and annotated under her direct supervision
  • Every report reviewed by professionals trained on her labels

Peer-reviewed evidence

Key publications

Foundation: development and validation of the ethogram

Development of an ethogram for a pain scoring system in ridden horses and its application to determine the presence of musculoskeletal pain

Research question

Can pain-related behaviours in ridden horses be systematically identified and scored to differentiate horses with musculoskeletal pain from those without?

Key finding

24 behaviours identified as significantly more frequent in horses with musculoskeletal pain, establishing a causal link. A score ≥8/24 is strongly associated with pain.

Authors & Journal

Dyson, Berger, Ellis & Mullard — Journal of Veterinary Behavior, 2018

DOI

https://doi.org/10.1016/j.jveb.2017.10.008

The Ridden Horse Pain Ethogram

Research question

What are the clinical applications and limitations of the RHpE for everyday use?

Key finding

The majority of the 24 behaviours are at least 10 times more likely to occur in a lame horse than in a non-lame horse.

Authors & Journal

Dyson — Equine Veterinary Education, 2022

DOI

https://doi.org/10.1111/eve.13468
Causal link: scores decrease once pain is resolved

Application of a ridden horse ethogram to video recordings of 21 horses before and after diagnostic anaesthesia

Research question

Do RHpE scores decrease when pain is eliminated by diagnostic anaesthesia — proving a causal relationship?

Key finding

In 21 lame horses, elimination of pain by diagnostic anaesthesia led to a significant reduction in RHpE scores, confirming the causal relationship between musculoskeletal pain and ridden behaviour.

Authors & Journal

Dyson & Van Dijk — Equine Veterinary Education, 2020

DOI

https://doi.org/10.1111/eve.13029

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

Research question

Is this causal link confirmed at a larger scale?

Key finding

In 150 horses investigated for a history of poor or reduced performance RHpE scores reduced substantially after diagnostic anaesthesia had removed pain.

Authors & Journal

Dyson et al. — Animals (MDPI), 2023

DOI

https://doi.org/10.3390/ani13121940
Predictive potential: RHpE scores and competition performance

Application of the Ridden Horse Pain Ethogram to Elite Dressage Horses Competing in World Cup Grand Prix Competitions

Research question

Do the world's best dressage horses have lower RHpE scores?

Key finding

Median score of 3/24 (range 0–7) among 147 competitors at World Cup Grand Prix from 2018 to 2020. Horses with better placings had significantly lower scores.

Authors & Journal

Dyson & Pollard — Animals (MDPI), 2021

DOI

https://doi.org/10.3390/ani11051187

Application of the Ridden Horse Pain Ethogram to Horses Competing at the Hickstead-Rotterdam Grand Prix and at National Affiliated Dressage Competitions

Research question

Do RHpE scores vary by competition level?

Key finding

Median scores were significantly higher at national level (4–6/24) than at World Cup level (3/24), suggesting pain burden varies with competition tier.

Authors & Journal

Dyson & Pollard — Animals (MDPI), 2021

DOI

https://doi.org/10.3390/ani11061820

Application of a Ridden Horse Pain Ethogram to horses competing at 5-star three-day-events: Comparison of scores at warm-up and competition

Research question

Do RHpE scores at warm-up predict performance across all phases of a 3-day event?

Key finding

Significant association between RHpE score at warm-up and dressage and cross-country performance. Horses with a RHpE score of 7 or more were more than twice as likely not to complete the cross-country course.

Authors & Journal

Dyson & Ellis — Equine Veterinary Education, 2022

DOI

https://doi.org/10.1111/eve.13415

Application of the Ridden Horse Pain Ethogram to Horses Competing in British Eventing 90, 100 and Novice classes

Research question

Does the score/performance relationship hold at amateur and novice levels?

Key finding

Across 1,010 competition starts, horses placed 1st, 2nd or 3rd had a median score of 2/24 compared to 4/24 for others. More than 9% of horses had an RHpE score of 8 or more. There was a significant relationship between RHpE scores and final placings. The pattern is consistent from novice to 5* elite.

Authors & Journal

Dyson & Pollard — Animals (MDPI), 2022

DOI

https://doi.org/10.3390/ani12050590
Influence of rider skill on scores

The influence of rider skill on ridden horse behaviour, assessed using the Ridden Horse Pain Ethogram

Research question

Can a highly skilled rider mask pain signals and distort the RHpE score?

Key finding

No. A more expert rider can improve locomotion quality — and may change which markers are expressed — but does not suppress the overall score in a genuinely painful horse.

Authors & Journal

Dyson, Martin, Bondi & Ellis — Equine Veterinary Education, 2022

DOI

https://doi.org/10.1111/eve.13434
The RHpE as an indicator of other pain sources — independent research

These studies were not conducted by Dr. Sue Dyson, but use the RHpE as an assessment indicator.

Improvement of gastric disease and ridden horse pain ethogram scores with diet adaptation in sport horses

Research question

Does a low-starch diet improve RHpE scores in horses with gastric ulcers?

Key finding

Yes. In 9 sport horses, switching to a low-starch diet (11% starch) over 12 weeks produced a significant reduction in RHpE scores alongside improvement in gastric ulcer scores.

Authors & Journal

Pineau et al. — Journal of Veterinary Internal Medicine, 2024

DOI

https://doi.org/10.1111/jvim.17223

Do tight nosebands have an effect on the upper airways of horses?

Research question

Do tight nosebands increase RHpE scores?

Key finding

Yes. RHpE scores were significantly higher with a tight noseband than with a correctly fitted one — suggesting noseband tightness is a measurable source of ridden discomfort.

Authors & Journal

Scholler, Wittenberg & Zablotski — Veterinary Medicine and Science, 2024

DOI

https://doi.org/10.1002/vms3.1478

A multimodal approach to equine thoracolumbar myofascial pain: integrating clinical examination, AI-based locomotion analysis and the Ridden Horse Pain Ethogram

Research question

Can the RHpE detect discomfort associated with thoracolumbar myofascial pain, combined with AI locomotion analysis?

Key finding

A multimodal study combining clinical examination, AI locomotion analysis and the RHpE to assess the effect of an equine physiotherapy intervention.

Authors & Journal

BMC Veterinary Research, 2026

DOI

https://doi.org/10.1186/s12917-026-05566-w
Pre-purchase examination and 4-year career follow-up

Pre-purchase examinations

Research question

Does adding ridden exercise and RHpE to a pre-purchase examination improve the accuracy of predicting long-term competition performance?

Key finding

In 25 sports horses, 86% of those considered a reasonable purchase risk (RHpE ≤4/24, no ridden lameness) competed at the same or higher level 3.5–4 years later, compared to only 6% of higher-risk horses. Overall classification accuracy was 92%. Odds ratio: 96 — recommended horses had 96× greater odds of competing successfully. Number needed to treat: 1.1 — for every 1.1 horses advised against purchase, one significant performance failure was prevented.

Authors & Journal

Dyson — Animals (MDPI), 2026

DOI

https://doi.org/10.3390/ani16132105

Kairon does not diagnose. It measures.

A score of 8 or more indicates that the ridden picture shows signs consistent with pain or discomfort. It is the starting point for a clinical conversation — not a conclusion. Every report is reviewed by a trained professional before it is released.

See how it applies to your situation