29/10/2025
Are we approaching asymmetry or laterality with curiosity… or with a pre-conceived bias?
It’s a question that’s been on my mind as we draw closer to the Vet Rehab Summit, and I’m spending more time preparing for each of the lectures.
Dr Kevin Haussler is speaking about “redefining laterality,” and that title alone has given me pause.
When I think laterality, my mind immediately goes to asymmetry - and from there, straight to lameness, pain, compensation, dysfunction, injury.
In my head, asymmetry is something to correct. It’s a sign that something isn’t right.
But then I read studies reporting that a huge percentage of performance horses - even at the highest levels - show measurable asymmetries, often without any obvious lameness.
And it makes me stop and think:
If these horses are still performing, are we looking at normal laterality?
Or are they, in fact, competing with undiagnosed pain or pathology?
That’s one side of the conversation:
Asymmetry = something is wrong.
Find it, fix it, restore balance.
But the other side says something quite different:
Asymmetry is normal.
Horses are naturally one-sided - just like humans.
Trying to make them perfectly symmetrical may be unrealistic, even unfair.
We hear it often - “he’s left-sided,” “she’s always been stiffer that way,” “it’s normal for them to favour one rein.”
And perhaps, in some cases, it really is.
But as Haussler reminds us in his 2025 paper, “The Challenge of Defining Laterality in Horses,” the reality is far more complex than either extreme.
The study outlines how what we interpret as laterality can actually be the result of a whole network of other factors - some benign, others not.
Among them:
▶️ Structural differences: variations in limb length, hoof balance, joint angles, or muscle development.
▶️ Functional or biomechanical asymmetries: uneven loading, stiffness, or range of motion linked to use patterns.
▶️ Pain and compensation: where injury, discomfort, or low-grade lameness drive protective movement patterns that look like “side dominance.”
▶️ Rider and handling influences: saddle fit, mounting habits, rein tension, the rider’s own asymmetry, and the way we lead or train.
▶️ Environmental factors: arena shape, surface type, turning direction, or even how horses are stabled and fed.
▶️ True neurological laterality: an innate preference for one side, which can influence motor control and coordination ( but is just one piece of the picture.)
Haussler’s point is clear: when we see asymmetry, we can’t jump to conclusions.
We have to ask why.
Because sometimes, that “left-sidedness” is nothing more than conformation and habit.
And other times, it’s the first whisper of discomfort, a subtle sign that the horse is protecting itself.
Our job is to stay curious long enough to tell the difference.
So perhaps the goal isn’t to eliminate every asymmetry, nor to accept them all as harmless.
It’s to understand the story behind them, to look for patterns across time, in different contexts, with and without a rider.
And speaking of the rider… we can’t separate them from the picture.
The rider’s posture, balance, strength, mounting routine, and even the distribution of rein tension can all shape what we perceive as the horse’s “bias.”
As Maria Teresa Engell will explore at the Summit, the horse and rider form one moving system - each influencing the other, for better or worse.
So as we head into the Vet Rehab Summit, I’m holding onto this:
Let’s approach laterality and asymmetry with curiosity rather than assumption.
Let’s be willing to ask why ▶️ and be open to answers that may not align with our bias.
And let’s keep seeing the horse, in all their beautiful complexity, as a conversation between structure, movement, training, and the human who guides them.