Why Do Horses Buck?

Introduction

If you’ve ever felt your horse lift their hindquarters with enthusiastic intent just as you ask for canter… you’ll know bucking isn’t subtle.

We’ve all been there, riding along happily and suddenly your horse pops its hind end into the air. At first, we might think it is naughty behaviour, but in most cases, it is the horse simply trying to let you know they are in discomfort or pain.

Traditionally, bucking has been labelled as freshness, cheekiness, or “having a moment.” But modern veterinary research, including work by the renowned equine researcher Dr Sue J. Dyson, shows that ridden bucking is frequently associated with musculoskeletal pain rather than misbehaviour [1].

And here’s the part many riders may not realise. Bucking isn’t just a behaviour issue. It’s often a performance issue.

Is Bucking Normal? What It Means in the Wild

Before we blame the saddle, bridle, or rider, we need to acknowledge something important. Horses evolved to buck. In feral and wild horses, bucking appears in two main contexts.

Firstly, play behaviour including bucking, rearing and kicking, helps develop coordination and musculoskeletal strength [2]. It’s essentially nature’s gym session.

Secondly, defensive bucking, which is serious business. A powerful upward thrust of the hindquarters could dislodge a predator clinging to the back. It’s explosive, coordinated, and biomechanically demanding. The picture of Tao bucking is showing a defensive buck, towards a field companion who has caused Tao to feel threatened.

So, bucking itself is normal. What is not normal is repeated bucking under saddle in a trained performance horse. That’s where we need to look into things a little deeper.

Bucking Is Not Bad Behaviour

Research, including work by Dr Sue J. Dyson, shows that bucking is often linked to pain, especially under saddle [1–3]. Multiple behaviours such as regular tail swishing, head tossing, stiff transitions, and of course bucking, all indicate your horse or pony has some level of pain. It is unlikely to be just a piggy attitude or stiffness that you may have been told to ride or work through by a well-meaning friend. In fact, research consistently shows that targeted diagnostic analgesia reduces pain-related ridden behaviours in affected horses [5]. Which tells us something important. If the bucking behaviour disappears when pain is addressed, it was never “naughty.” It was communication.

The Ridden Horse Pain Ethogram (RHpE) devised by Dr Sue Dyson and Danica Pollard identifies 24 behaviours more likely in horses with musculoskeletal pain [4]. Vets and other equine health practitioners trained in the RHpE can train themselves to detect subtle signs of pain and discomfort that might be thought of as resistance or naughtiness [1].

We must remember that bucking can be caused by many things such as ulcers, dental issues, and saddle fit, to name a few. In this article we are looking at musculoskeletal issues that may lead to bucking.

When Are Horses Most Likely to Buck

We are now just looking at pain-related bucking which usually happens more often under saddle, than on the lunge. Rider weight and imbalance increase spinal and pelvic loading, especially during canter transitions, which is why discomfort becomes obvious. In a study of nearly 300 horses with sacroiliac (SI) region pain, 65% had a poor contact with the bit, 81% had poor quality canter and 35% bucked or kicked out with a hindlimb during canter, bucking was seen mostly under saddle [2].

However, if your horse is calm and happy at walk and trot on the lunge but starts bucking when you ask for canter, or this behaviour is seen when ridden, again especially at canter, please pay attention as this is a clear warning signal [2,3].

Thoracolumbar Back Pain: When the Spine Becomes the Problem

The thoracolumbar spine (from mid-back to lumbar region) acts as a bridge between the forehand and hindquarters. It transfers force, stabilises movement, and allows the horse to round and extend.

This region contains articular facet joints, dorsal spinous processes, the supraspinous ligaments and the deep stabilising muscles such as multifidus.

Facet joint inflammation and back pain are well documented in ridden horses [3]. When pain is present in this region, horses often demonstrate altered spinal mechanics and behavioural resistance. Research has shown a strong association between ridden behavioural abnormalities which include bucking and underlying musculoskeletal pain [1].

What does thoracolumbar pain-related bucking look like?

Typically, the buck is one where the horse rounds it’s the back, there is no dramatic kick-out, it often happens in upwards transitions and is often worse at canter.

These horses may also hollow their backs under saddle at other gaits, struggle with rein and bit contact and show resistance to collection with a reduced elasticity seen in their trot.

This thoracolumbar pain impacts performance due to reduced lumbar extension and limited muscle engagement causing reduced spinal stability. If the spine cannot extend and stabilise correctly, the horse cannot elevate the forehand effectively. That affects everything from medium trot to jump bascule.

In short: thoracolumbar pain causes reduced spinal stability, which reduces athletic expression and performance.

Sacroiliac Pain and the “Kick-Out” Buck

Now we move slightly further back along the horse’s spine to the sacroiliac (SI) region. The SI joint is not designed for large movement. Its job is stability and force transmission. It transfers propulsive forces from the hindlimbs into the axial skeleton [4] consisting of the spine and skull.

The SI joint is supported by strong dorsal and interosseous ligaments. When these structures are inflamed or strained, joint instability can occur. Studies examining horses diagnosed with sacroiliac region pain found bucking to be a common presenting complaint, particularly under saddle and especially at canter [5].

What does SI-related bucking look like?

Often this buck includes the hind limb kick-out often repeatedly on the same side (unilateral), and again occurs most often during upwards transitions into canter. It may well also be seen when a horse lands after jumping a fence and in most cases is worse on one rein.

That unilateral kick-out is clinically important. It often reflects asymmetrical force transmission through the pelvis causing discomfort on the side of the limb that is kicking out. Performance implications are not just bucking but also include loss of straightness, difficulty with lateral work, disunited canter, reduced power and reluctance to move forward as expected and a flattened jump.

The sacroiliac joint is the region of propulsion, pain here is like asking an athlete to sprint with a pulled hamstring. The intention is there but the power simply isn’t.

Why Bucking Often Happens at Canter

If there were a “most biomechanically demanding gait” award, canter would win.

Canter involves asymmetrical loading, greater lumbosacral flexion, increased vertical oscillation and higher propulsive force generation culminating in increased loading across the sacroiliac and lumbar regions during canter [4].

Now add rider weight, demands of collection, and a jump and you have peak axial loading. If discomfort exists anywhere in the thoracolumbar or SI region, canter is usually where it becomes visible. Which is why many owners report, “He’s fine in walk and trot… but bucks when I ask for canter.”

The timing of a bucking horse is not random.

Types of Bucking and What They Mean

Not all bucks are equal. Owners and riders must observe the pattern and context, and associated behaviours.

The Ridden Horse Pain Ethogram: It’s Not Just the Buck

One of the most influential developments in equine behavioural assessment is the Ridden Horse Pain Ethogram (RHpE), developed by Dyson and colleagues [1]. Which identifies 24 behaviours associated with musculoskeletal pain under saddle.

Bucking is rarely isolated. It is often accompanied by persistent tail swishing, head being held behind the vertical, ears pinned, reluctance to go forward, and as already mentioned resistance in transitions especially canter.

When these behaviours accumulate, the likelihood of underlying pain increases significantly [1]. From a performance perspective, these subtle signs often precede measurable decline. Meaning these behaviours are seen well before your scores drop, before refusal to jump, and before the explosive buck.

By the time a horse escalates to bucking, they will have already exhausted quieter ways of expressing their discomfort. The whisper wasn’t heard so now they have to shout!

How Bucking Affects Performance (Even If You Stay On)

Let’s be honest, sometimes the rider stays on and just carries on. This really is not the answer and not just because of the safety aspect. Bucking changes biomechanics and this repeated incorrect axial flexion and instability lead to, reduced stride consistency, compensatory limb loading, muscle fatigue and decreased endurance. Ultimately it will lead to tissue changes that may not be reversible.

Studies show that rehabilitation targeting spinal stabilisers such as multifidus improves back function and muscular symmetry [6]. This reinstates the spinal stability.

For all horses, non-competitive and competitive – regardless of discipline, their spinal health underpins their ability to perform collection, have correct engagement of their hind end, to bascule properly over a jump, or simply to move freely at all gaits.

Spinal function and stability, performance and longevity are inseparable.

What Should You Do If Your Horse Is Bucking?

Correcting your horses pain response with stronger leg aids is rarely a long-term strategy, unless your goal is involuntary flying lessons.

Your first person to call is your vet. By law in the UK Vets are the head of the equine therapy team, and they are the only ones allowed to diagnose. This is really important because bucking can be caused by other issues and not just musculoskeletal pain. Your vet will conduct a thorough examination, possibly using nerve blocks of the SI region [2], to help them to pinpoint the source of the issue.

Once your vet has done their assessment, they may recommend chiropractic treatment to help realign the spinal and pelvic bones and/or physiotherapy to ensure a thorough rehabilitation program is put in place. This must include core strengthening and dynamic mobilisation to improve spinal stability [6].

Any necessary training adjustments will come after a through medical assessment. And of course, this is also a really good time to get your saddle fit checked because if that was the primary cause you don’t want to start the cycle all over again.

Final Thoughts

Bucking is a powerful behaviour pattern deeply rooted in equine survival. However, in the ridden horse, it is often a red flag. Particularly when associated with thoracolumbar or sacroiliac dysfunction.

Understanding the difference between exuberance and pathology protects the rider’s safety, the horse’s welfare and athletic longevity. Perhaps most importantly, it allows the horse to perform comfortably, rather than defensively.

At the end of the day, the goal isn’t just fewer bucks, it’s better performance through better biomechanics.

Written by Liz Wenman MSc, PGCert, BSc, MMAA, MMCP.

About Me

I am a fully qualified equine practitioner with extensive training and over a decade of  professional experience. I take a whole-horse approach to supporting physical, energetic, and  emotional wellbeing, with a focus on comfort, performance, and long-term quality of life. My  work is grounded in both advanced training and a lifelong connection with horses.

References:

1. Dyson S, Pollard D. Application of the Ridden Horse Pain Ethogram to 150 Horses with Musculoskeletal Pain. Animals (Basel). 2023;13:1940.
2. Cameron EZ, Linklater WL. Play behaviour and motor development in horses. Behav Processes. 2017;138:67–72.
3. Greve L, Dyson S. The interrelationship of lameness and back pain in the ridden horse. Equine Vet Educ. 2016;28(6):343–349.
4. Clayton HM, Hobbs SJ. The role of biomechanical analysis in equine locomotion research. Equine Vet J. 2017;49(5):560–568.
5. Dyson S, Murray R, Schramme M, Branch M. Sacroiliac joint region pain in sports horses. Equine Vet Educ. 2019;31(8):427–436.
6. Stubbs NC, Kaiser LJ, Hauptman J, Clayton HM. Dynamic mobilisation exercises increase multifidus cross-sectional area. Equine Vet J. 2019;51(2):222–228.