Delving into the Complex Subject of Soundness and Symmetry in Horses

Our recent Conference brought together a wealth of leading experts over two days to explore one of the most fascinating, and often misunderstood, topics in the equine world, Soundness and Symmetry.

In our previous article, we focused on the highlights from day one. In this article we delve into day two. From the science of laterality to rehabilitation, nutrition, and welfare, the day highlighted just how complex the subject of soundness and symmetry really is. While symmetry is often viewed as the ideal, the speakers over the whole weekend made it clear that the reality is far more layered. Just like humans, horses are naturally asymmetrical and understanding the difference between normal variation and when it is more serious is essential for anyone working with horses.

Here’s a snapshot of what each speaker shared during day 2 of the conference.

Understanding Laterality in Horses

Dr Kevin Haussler opened the second day of the conference by exploring the concept of laterality, the natural tendency for one side of the body to be used more than the other. This is a normal feature of biology seen across many species, including humans. He started by saying that even with over 200 papers published on the topic of laterality in horses, there are still many questions that are unanswered.

Dr Kevin Haussler delved into the complex subject of laterality in horses

In its broadest sense, laterality reflects dominance of one cerebral hemisphere in controlling specific sensory, motor, or behavioural functions, or dominance of one structure within paired organs or limbs. In horses, laterality is most often discussed in terms of limb preference, sidedness of movement, and asymmetries observed during stance, locomotion, and ridden work. Importantly, these patterns are not automatically a problem. Laterality exists on

a spectrum, ranging from normal functional specialisation to asymmetry that may be linked to pain or dysfunction.

Kevin highlighted that horses often show mixed patterns of sidedness. A horse might prefer one forelimb for initiating movement but load the opposite hindlimb more during propulsion. These preferences can also change depending on context, particularly when a rider, saddle, or the demands of training are involved.

The take home question is whether laterality should be changed. Evidence from human and equine studies suggests forced alteration of innate motor preferences can have negative physical and psychological consequences. Rather than attempting to “correct” laterality, intervention should focus on:

• Identifying pain-driven asymmetries

• Supporting balance, coordination, and strength

• Optimising tack, training, and conditioning

• Treating underlying pathology when present

Motor laterality appears more flexible than sensory laterality, but even then, the goal should be functional improvement, not enforced symmetry

Kevin finished his presentation by stressing that laterality in horses is not a flaw to be eliminated but a biological feature to be understood. Laterality reflects a complex neural network integrating sensory input, motor output, behaviour, training and environment. The task is not to decide which side is “normal,” but to determine whether observed asymmetries are adaptive, neutral, or harmful. The focus needs to shift from chasing symmetry to supporting soundness, performance and welfare.

The Wonders of Water

Water treadmills are now widely used in training and rehabilitation settings, but Dr Kathryn Nankervis reminded us in her presentation that their effectiveness depends entirely on understanding the purpose behind their use.

Before stepping onto a water treadmill, it’s essential to ask why it’s being used. Is it part of a rehabilitation programme? A tool for conditioning? Or simply a way to add variety through cross-training?

The use of water treadmills for training and rehabilitation of horses was discussed with Dr Kathryn Nankervis

Movement on a treadmill belt is already different from over ground movement, and adding water introduces the range of motion of the lower limb joints. Water resistance encourages increased joint flexion in the lower limbs and can increase range of motion. As water depth increases (i.e. water above the hock) we can expect greater range of movement from more proximal joints.

However, speed and water depth must be carefully balanced. If the treadmill moves too quickly in deeper water, horses may struggle to maintain correct movement patterns, leading to trailing hind limbs or excessive head and neck movement. Guidelines for water treadmill use recommend decreasing speed as water depth increases.

Kathyrn emphasised that well-designed training protocols and careful observation of movement quality are crucial. Research is increasingly showing that regular, well-managed water treadmill exercise can improve muscle development and postural stability, but only when programmes are tailored to the individual horse. The water treadmill is another tool in your toolkit that be used to help horses during fitness work and rehab.

Nutrition and the Role of Gut Health

Professor Meriel Moore-Colyer gave us a whistle-stop tour bringing us all up to date with current equine nutrition research that's improving our understanding of gut health and how it impacts on the horse.

The equine digestive system hosts a vast microbiome, the community of microorganisms living within the gut. While researchers have studied these microbes extensively, recent work is increasingly focusing on the metabolome, which refers to the chemical products created during digestion and fermentation.

These metabolic outputs may give a clearer picture of how diet is affecting gut health than simply analysing microbial populations. Changes in forage type, feeding patterns, or sudden dietary shifts can all influence these digestive processes. One study showed us that the first five days of changing the horse's diet are the 'danger period' and the time where you need to be careful and watch the horse carefully especially if they are predisposed to laminitis or any other metabolic conditions.

Equine obesity was a topic that Professor Meriel Moore-Colyer looked at during her presentation

Another major topic Meriel discussed was the ongoing equine obesity crisis, with a recent study in Ireland recording levels as high as 45%. She also stressed that obesity affects not only weight but also metabolic function and the gut microbiome itself.

Meriel highlighted practical strategies that owners can use to monitor body condition and reduce excess weight, emphasising that small management changes, particularly around forage provision and feeding practices, can make a significant difference to long-term health. She also stressed the importance of exercise, restricting grass alone won’t help reduce weight. High intensity exercise is best, three to six days a week. Include hill-work, pole work, water treadmill. It’s important to put them to work to help them lose the weight.

Evidence-Based Treatment and Rehabilitation

Physiotherapist Gillian Tabor followed on from her talk the previous day on Musculoskeletal Assessment and this time focused on the importance of clinical reasoning when designing treatment and rehabilitation programmes. Her opening point was that when it comes to treating horses there is no recipe book, and that working with the horse’s multidisciplinary team is the way forward, it accelerates and enhances the outcome.

Rather than aiming for perfect symmetry, the primary goal should always be comfortable, functional movement suited to the horse’s discipline and workload. What’s required from a high-level dressage horse will differ from the needs of a leisure horse, but both must be able to move comfortably and cope with the demands placed upon them.

Gillian discussed how manual therapies, soft tissue techniques, and electrotherapeutic devices can all play a role in treatment when used with clear purpose. However, the foundation of long-term improvement is almost always progressive, functional exercise.

Exercises designed to improve spinal mobility, balance, and coordination in the standing horse can form the basis of many rehabilitation programmes. The effectiveness of these exercises depends not only on selection, but also on correct “dosage”, consistency, and the skill of the handler or rider performing them.

Gillian also highlighted the importance of variety of exercise and the valuable impact of in-hand work. Above all, rehabilitation must remain flexible. Horses respond differently, and programmes should be continually reassessed and adjusted based on both clinical findings and how the horse is responding.

Skeletal Asymmetry

Dr Kirsty Lesniak examined the structural side of asymmetry, focusing on differences in the left and right sides of the equine skeleton.

Kirsty talks about skeletal asymmetry

Perfect symmetry is rarely achieved in nature. Instead, most animals show small variations in bilateral traits such as limb dimensions or skeletal landmarks. These variations can arise during early development due to genetic and environmental influences.

One type, known as fluctuating asymmetry, represents small random differences between the two sides of the body. Interestingly, levels of this asymmetry can sometimes reflect the developmental challenges an animal experienced during growth.

Research in both humans and horses suggests that more symmetrical individuals may sometimes demonstrate higher athletic performance. For example, studies in racehorses and event horses have found lower levels of asymmetry in higher-performing individuals.

However, some asymmetries appear to be linked to the demands of specific disciplines. For example, racehorses trained on tracks that run consistently in one direction may develop subtle skeletal adaptations over time.

Dr Lesniak’s work highlights that asymmetry may arise from multiple sources, development, training, environment, and biomechanics, and that understanding these influences is essential when evaluating the horse’s movement and performance.

A Conflict Between Welfare and Performance

Closing the conference, Roly Owers explored the relationship between equine welfare and sporting performance.

Roly Owers gave a thought provoking final presentation on welfare and performance

Modern welfare science has significantly expanded our understanding of horses’ physical and emotional needs. Increasingly, welfare is defined not only by the absence of negative experiences but also by the presence of positive ones.

Roly emphasised the importance of the “three Fs” of equine management: friends, forage, and freedom of movement. These fundamental needs are not incompatible with sport horse management and can support both well-being and performance.

The discussion also explored whether our current definitions of performance truly reflect the horse’s experience. In many equestrian disciplines, success is judged primarily on athletic or aesthetic outcomes. However, judging systems could evolve to place greater emphasis on signs of comfort, harmony, and positive engagement between horse and rider.

Indicators such as relaxed posture, fluid movement, and light communication through the reins could help reward training approaches that prioritise both welfare and longevity.

The key message was clear and a great way to finish the 2026 conference - high-level performance and excellent welfare should not be seen as opposing goals. When horses are comfortable, confident, and well-managed, they are more likely to perform well and remain sound throughout their careers.

Rethinking Symmetry

Across all the presentations, one message stood out. Symmetry and soundness are influenced by so many factors including training, management, environment, and individual variation.

Rather than striving to eliminate every asymmetry, the challenge is to recognise which differences are natural and which may signal a problem. By combining scientific research with careful observation and thoughtful training practices, we can support horses in achieving both soundness and long-term performance.

The Horses Inside Out Conference once again demonstrated the value of bringing together experts from different fields. When biomechanics, veterinary science, nutrition, rehabilitation, and welfare perspectives meet, a richer and more balanced understanding of the horse emerges.

As one conference ends, out attention turns to the next. Wellness and Welfare is the subject for the 2027 Conference - February 20 and 21. Pop the date in your diary - you don't want to miss it.